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AB Quality ALLEN-BRADLEY 1771-QB User Manual

Linear positioning module
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Linear Positioning Module
Cat. No. 1771-QB
User Manual

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Summary of Contents for AB Quality ALLEN-BRADLEY 1771-QB

  • Page 1 Linear Positioning Module Cat. No. 1771-QB User Manual...
  • Page 2 Important User Information Because of the variety of uses for the products described in this publication, those responsible for the application and use of this control equipment must satisfy themselves that all necessary steps have been taken to assure that each application and use meets all performance and safety requirements, including any applicable laws, regulations, codes and standards.
  • Page 3 Table of Contents Preface ........Introducing the Linear Positioning Module .
  • Page 4 Table of Contents Hardware Description ......Installing the Linear Positioning Module ....
  • Page 5 Table of Contents Interpreting Module to PLC Data (READS) ... . . Formatting Module Data (WRITES) ....
  • Page 6 Table of Contents Initializing and Tuning the Axes ..... Advanced Features ......
  • Page 7 Table of Contents Sample Application Programs ..... . 10 1 Troubleshooting ....... . 11 1 Glossary of Terms &...
  • Page 8 Table of Contents Data Formats ........Product Specifications .
  • Page 9 Preface Preface This manual explains how to install and configure the Linear Positioning Module. It includes sample application programs to illustrate how to program a to work with the Linear Positioning Module. Organization of the Manual This manual contains eleven chapters and nine appendices that address the following topics: Chapter Title...
  • Page 10 Preface Chapter Title Describes: Appendix E Command Block command block word assignments Appendix F Motion Block motion block word assignments Appendix G Hexadecimal Data Table Form hexadecimal data worksheets Appendix H Data Formats valid data formats Appendix I Specifications 1771 QB product specifications Product Audience Read this manual if you intend to install or use the Linear Positioning Module...
  • Page 11 Preface Frequently Used Terms Appendix A contains a complete glossary of terms and abbreviations used in this manual. To make this manual easier for you to read and understand, product names are avoided where possible. The Linear Positioning Module is also referred to as the “module”.
  • Page 12 Chapter Introducing the Linear Positioning Module What is the Linear Positioning The Linear Positioning Module (Cat. No. 1771-QB) is a dual-loop position Module? controller occupying a single slot in the Allen-Bradley 1771 Universal I/O chassis. It can control servo or proportional hydraulic valves, or some electric servos.
  • Page 13 Chapter 1 Introducing the Linear Positioning Module Product Compatibility PLCs You can use the module with any Allen-Bradley PLC that uses block transfer programming in local 1771 I/O systems including: PLC-2 family PLC-3 family PLC-5 family - PLC-5/10 (Cat. No. 1785-LT4) - PLC-5/11 (Cat.
  • Page 14 Chapter 1 Introducing the Linear Positioning Module Santest Co. Ltd. c/o Ellis Power Systems 123 Drisler Avenue White Plains, NY 10607 (914) 592-5577 Lucas Schaevitz Inc. 7905 N. Route 130 Pennsauken, NJ 08110-1489 (609) 662-8000 All four manufacturers provide versions of the transducer that connect directly to the module’s wiring arm, without an external digital interface box.
  • Page 15 Chapter 1 Introducing the Linear Positioning Module System Overview Figure 1.2 shows one of the module’s two control loops within a linear positioning system for closed-loop axis control. The module communicates with a programmable controller through the 1771 backplane. The programmable logic controller sends commands and user-programmed data from the data table to the module as directed by a block-transfer write instruction.
  • Page 16 Chapter 1 Introducing the Linear Positioning Module The module also connects to linear displacement transducers (one for each of the two axes) via wiring arm terminals. The transducer senses the axis position and feeds it back to the module, thereby closing the control loop. The module’s built-in processor samples the linear displacement transducer interfaces and determines positions along each of the two axes every two milliseconds.
  • Page 17 Chapter Positioning Concepts This chapter explains concepts and principles of axis positioning. If you are thoroughly familiar with the concepts of closed-loop servo positioning, you can go on to Chapter 3. Axis Motion Figure 2.1 illustrates a typical method of converting the flow of fluid into a linear displacement.
  • Page 18 Chapter 2 Positioning Concepts Closed Loop Positioning Closed-loop positioning is a precise means of moving an object from one position to another. In a typical application, a positioning device activates a servo valve controlling the movement of fluid in a hydraulic system. The movement of fluid translates into the linear motion of a hydraulic cylinder.
  • Page 19 Chapter 2 Positioning Concepts Figure 2.3 Circulations resolution = 0.002 Gate (received from transducer) Duration (1 circulation) resolution = 0.001 Gate (received from transducer) Duration (2 circulations) 50035 A Simple Positioning Loop To move a specified distance along an axis, you can command the hydraulic device to move at a specific velocity for a specific length of time.
  • Page 20 Chapter 2 Positioning Concepts In Figure 2.4: desired velocity is the desired speed of axis motion from one position to another position command equals the integration of velocity over time actual position value (transducer feedback) is the actual position of the axis as measured by the LDT following error equals position command minus actual position velocity command is generated by amplifying the following error and...
  • Page 21 Chapter 2 Positioning Concepts Feedforwarding To decrease the following error without increasing the gain, you can add a feedforward component. (See Figure 2.5.) Figure 2.5 Positioning Loop with Feedforwarding Feed Forward Desired Position Following Velocity Velocity Command Error Command Servo Valve Integrator Axis Actual...
  • Page 22 Chapter 2 Positioning Concepts Without integral control, the axis responds only to the size of the positioning error, not its duration. Integral control responds to both the size and duration of the positioning error. Thus, the integral term continues to adjust the velocity command until it achieves an exact correction.
  • Page 23 Chapter 2 Positioning Concepts Figure 2.7 Derivative Control Feed Forward Integrator Desired Position Following Velocity Velocity Command Error Command Servo Valve Derivative Integrator Axis Actual Linear Position Displacement Transducer 50039 Deadband Most systems have friction and play in their mechanical linkages. These characteristics can cause a cylinder to oscillate around a programmed endpoint–especially if you use an integral term.
  • Page 24 Chapter 2 Positioning Concepts You can control the integral and derivative components by defining a PID (proportional, integral and derivative) band. The PID band is a region surrounding the programmed endpoint where the system enables integral or derivative terms. As a result, the integral and derivative components affect only the final positioning of the axis.
  • Page 25 Chapter Positioning with the Linear Positioning Module This chapter explains how the Linear Positioning Module interacts with a programmable controller to control axis movement within a linear positioning system. How the Module Fits in a Figure 3.1 shows how the module functions in a typical positioning system. Positioning System Note that the positioning loop closes in the module and functions independently of the programmable controller’s I/O scan rate.
  • Page 26 Chapter 3 Positioning with the Linear Positioning Module How the Module Interacts with The module is a dual-loop position controller, occupying a single slot in the a PLC Allen-Bradley 1771 universal I/O chassis. The module communicates with the PLC through the 1771 backplane. There are two kinds of transfers–read operations and write operations.
  • Page 27 Chapter 3 Positioning with the Linear Positioning Module Figure 3.2 Trapezoidal Axis Movement Velocity Constant Velocity Final Velocity Acceleration Deceleration Time Start Finish 50002 The actuator may not reach the final velocity during a short move which may only consist of acceleration and deceleration phases without a constant velocity phase.
  • Page 28 Chapter 3 Positioning with the Linear Positioning Module Figure 3.4 Axis Movement with Velocity Curve Smoothing Velocity Constant Velocity Final Velocity Acceleration Deceleration Time Start Finish Acceleration Final Accel Finish Time Start Final Decel Deceleration 50004 Commanding Motion There are three ways to specify module axis motion: by setpoints, by jogging or by motion blocks.
  • Page 29 Chapter 3 Positioning with the Linear Positioning Module turn on a hardware start enable bit (using the command block), which causes the module to delay movement to the commanded setpoint. The delay ends and movement starts when you activate the hardware start input or send a software start command in the command block.
  • Page 30 Chapter Hardware Description This chapter describes the Linear Positioning Module hardware, as well as other hardware required for a positioning system. Indicators Figure 4.1 shows the three indicators on the module. Figure 4.1 Indicators LINEAR POSITIONING FAULT LOOP1 ACTIVE LOOP2 ACTIVE 50009 When you first power up the module, all three indicators turn on for about one...
  • Page 31 Chapter 4 Hardware Description Wiring Arm Terminals The module draws power for its internal circuitry and communicates with the programmable controller through the 1771 universal I/O chassis. You make all other connections through the wiring arm terminals. Cable length can be up to 200 feet for these connections, depending on the gauge used.
  • Page 32 Chapter 4 Hardware Description analog output interface terminals discrete output terminals The terminals for these four groups are divided between loop 1 and loop 2. Odd number terminals are for loop 1; even numbered terminals apply to loop 2. Transducer Interface Terminals 1 through 8 on the module’s wiring arm provide connection points for the transducer interface.
  • Page 33 Chapter 4 Hardware Description Use these equations to determine the maximum length and positioning resolution for the transducer: maximum length = 1680/(T x N) resolution = 1/(58.5 x T x N) where: T = transducer constant stamped on transducer head (typically 9.0500 microseconds per inch) N = number of circulations The following table gives several maximum transducer lengths assuming a...
  • Page 34 Chapter 4 Hardware Description Discrete Inputs Terminals 13 through 26 on the module’s wiring arm provide connection points for discrete input signals. Seven terminals (for each loop) connect to seven discrete inputs. The use of these inputs is optional. If you do not want to use them, you can disable them through the parameter block.
  • Page 35 Chapter 4 Hardware Description Figure 4.3 Simplified Schematic of a Discrete Input 1771 - QB MODULE INPUT SUPPLY + 5V DISCRETE INPUT (e.g. JOG FWD) 3.3K INPUT COMMON 50041 Auto/Manual Input The module accepts the signal at the AUTO/MAN terminal (13/14) as the auto/manual input.
  • Page 36 Chapter 4 Hardware Description Hardware Stop Input The module accepts the signal at the STOP terminal (17/18) as a low-true hardware stop input. A low signal at the hardware stop input disables the analog output and stops axis movement. Unless the discrete inputs are disabled via the parameter block, this input must be high for normal operation.
  • Page 37 Chapter 4 Hardware Description The analog output interface circuit is electrically isolated from the 1771 I/O chassis. This feature protects other devices on the 1771 backplane from noise and current surges in the analog output circuit. An internal relay automatically shuts off these outputs in the event of a module fault.
  • Page 38 Chapter 4 Hardware Description Important: If you want to connect a discrete output of one axis to the discrete input of another axis, the minimum discrete output supply voltage is 11.6 VDC. This accounts for the voltage drop of 1.6 VDC shown above and provides the minimum voltage required to drive a module discrete input (10 VDC).
  • Page 39 Chapter 4 Hardware Description to power the: supply: to these terminals: Transducer interface +5 VDC 9, 10 Discrete inputs +24 VDC (max) 27, 28 Servo valve interface +15 VDC 33, 34, 35 Discrete outputs +30 VDC (max) All power connections must be made for the transducer, servo valve, and discrete outputs.
  • Page 40 Chapter Installing the Linear Positioning Module Before You Begin This chapter tells you how to install the module in the I/O chassis and how to configure the module’s analog outputs by setting DIP switches. Before you install the module: make sure your power supply is adequate plan your module’s location in the I/O chassis take steps to avoid electrostatic discharge Avoiding Backplane Power Supply Overload...
  • Page 41 Chapter 5 Installing the Linear Positioning Module Electrostatic Discharge Under some conditions, electrostatic discharge can degrade performance or damage the module. Observe the following precautions to guard against electrostatic damage: use a static-free workstation if one is available touch a grounded object to discharge yourself before handling the module don’t touch the backplane connector or connector pins when you set the analog output switches, don’t touch other circuit components inside the module...
  • Page 42 Chapter 5 Installing the Linear Positioning Module Figure 5.1 Locating the Analog Configuration Switches CURRENT RANGE LOOP 2 VOLTAGE/CURRENT CURRENT RANGE LOOP 1 VOLTAGE/CURRENT 50043 Use a blunt pointed instrument (such as a ballpoint pen) to set the switches. ATTENTION: Don’t use a pencil to set switches. Lead can jam the switch.
  • Page 43 Chapter 5 Installing the Linear Positioning Module Set the current/voltage switch for each control loop as shown in Figure 5.2. Figure 5.2 Configuring the Analog Outputs LOOP 1 LOOP 2 OPEN OPEN 1771 QB Chassis OPEN 100mA OPEN TYPES OF SWITCHES 50mA OPEN SLIDE...
  • Page 44 Chapter 5 Installing the Linear Positioning Module Keying A package of plastic keys (Cat. No. 1771-RK) is provided with every I/O chassis. When properly installed, these keys prevent the seating of anything but the module in the keyed I/O chassis slot. Keys also help to align the module with the backplane connector.
  • Page 45 Chapter 5 Installing the Linear Positioning Module Open the module locking latch on the I/O chassis and insert the module into the slot keyed for it. Press firmly to seat the module into the backplane connector. Secure the module with the module locking latch. ATTENTION: Don’t force a module into the backplane connector.
  • Page 46 Chapter 5 Installing the Linear Positioning Module Figure 5.4 Shielded Cable Grounding Connections Transducer Supply LINEAR POSITIONING FAULT Transducer LOOP1 ACTIVE LOOP2 ACTIVE Discrete Input Supply Servo Valve Analog Supply Discrete Shielded cables are not Output required for these discrete Supply inputs and outputs.
  • Page 47 Chapter 5 Installing the Linear Positioning Module Using Twisted Wire Pairs It is recommended you use twisted wire pairs for a signal and its return path to reduce noise levels further. Figure 5.5 shows a twisted pair and shielded twisted pair.
  • Page 48 Chapter 5 Installing the Linear Positioning Module Figure 5.6 AC Power and Ground Connections Disconnect Incoming Fuses Isolation/ Step Down Transformer Fuse 120 VAC Central Ground Bus Power Power Power Power Power Supply for Supply for Supply for Supply for Supply for Discrete Discrete...
  • Page 49 Chapter 5 Installing the Linear Positioning Module Power Supplies The 1771 backplane provides the power for most of the module circuits. You’ll need external power supplies for the analog outputs, transducer interfaces, discrete inputs and discrete outputs. All four power supplies and their associated module circuits are electrically isolated from the I/O chassis and from each other.
  • Page 50 Chapter 5 Installing the Linear Positioning Module Figure 5.7 Transducer Connections LOOP 2 LOOP 1 Connect to TRANSDUCER TRANSDUCER Transducer Head +5 Com Transducer Ground the shield at Supply the I/O chassis end. (Customer Supplied) Wiring Arm Terminals LOOP 2 LOOP 1 +GATE +GATE...
  • Page 51 Chapter 5 Installing the Linear Positioning Module Connect - VDC from your power supply to the transducer. Connect the common terminal on your power supply to the +5 COMMON terminal (10) on the module, to ground at the I/O chassis, and to the transducer.
  • Page 52 Chapter 5 Installing the Linear Positioning Module Make sure that the voltage driving each input is at the appropriate level. Figure 5.8 shows the discrete input connections. Figure 5.8 Discrete Input Connections Auto/Manual Auto/Manual Start Start Use any number of Use any number of E stop switches in series E stop switches in series...
  • Page 53 Chapter 5 Installing the Linear Positioning Module Power Supply To connect the discrete input power supply, follow these steps: Connect the (+) side of the discrete input power supply to the I/P SUPPLY terminal (27) of the module. Connect the common of the discrete input power supply to the I/P COMMON terminal (28) of the module.
  • Page 54 Chapter 5 Installing the Linear Positioning Module ATTENTION: In servo valve control systems, axis drift may occur due to imprecise valve nulling even with zero analog output. It is recommended that emergency stop switches, such as overtravel limit switches, also turn off axis power and close a blocking valve installed between the servo valve and the prime mover.
  • Page 55 Chapter 5 Installing the Linear Positioning Module Jog Reverse Input The jog reverse input is valid only in the manual mode. The jog reverse input is similar to the jog forward input, except the axis movement is in the reverse direction (the direction of negative movement relative to the zero-position offset).
  • Page 56 Chapter 5 Installing the Linear Positioning Module Pull-down resistors or double-throw switches are only required if you wish to connect two or more QB’s. They are not required to control multiple discrete inputs on a single module. Figure 5.10 Using Pull Down Resistors to Control Multiple QB's Module A Wiring Arm LOOP2...
  • Page 57 Chapter 5 Installing the Linear Positioning Module Connecting the Analog The analog outputs provide the current (or voltage) by which the module Outputs controls the servo valve. By controlling the servo valve, the module controls axis motion. ATTENTION: Applying output to an axis with polarity reversed can cause sudden high-speed motion.
  • Page 58 Chapter 5 Installing the Linear Positioning Module ATTENTION: The polarity of the analog outputs is affected by the setting of the most significant bit of the analog range words in the parameter block. (See Chapter 7.) Incorrect wiring of the analog outputs or an incorrect setting of this most significant bit can cause the axis to accelerate out of position when the loop is closed.
  • Page 59 Chapter 5 Installing the Linear Positioning Module Connecting the Discrete The two discrete outputs for each loop are powered by the discrete output power Outputs supply. The characteristics of the discrete outputs are: no voltage applied to the output High output supply voltage applied to output Maximum Current 100 mA...
  • Page 60 Chapter 5 Installing the Linear Positioning Module Power Supply To connect the discrete output power supply, follow these steps: Connect the (+) side of the discrete output power supply to the O/P SUPPLY terminal (40) on the module. Connect the common of the discrete output power supply to ground at the I/O chassis and to the returns (-) of all output devices.
  • Page 61 Chapter 5 Installing the Linear Positioning Module Figure 5.13 Connecting a Discrete Output to a Discrete Input Wiring Arm Terminals Wiring Arm LOOP 1 LOOP 2 Terminals AUTO/MAN LOOP 2 LOOP 1 AUTO/MAN START OUTPUT 1 OUTPUT 1 START STOP OUTPUT 2 OUTPUT 2 STOP...
  • Page 62 Chapter Interpreting Module to PLC Data (READS) This chapter explains how to monitor module operation from a programmable controller by reading and interpreting status block data that the module transfers to the programmable controller’s data tables. PLC Communication Overview You must program the programmable controller to communicate with the Linear Positioning Module through block read and block write instructions.
  • Page 63 Chapter 6 Interpreting Module to PLC Data (READS) Word Assignment The assignment of the words within the status block is as follows: Figure 6.1 Status Block Word Assignments WORD DESCRIPTION AXIS 1 AXIS 2 Module Configuration Word Status word 1 Default Status Status word 2 (MS) Position/Error/Diagnostic word...
  • Page 64 Chapter 6 Interpreting Module to PLC Data (READS) Figure 6.2 Module Configuration Word 15 14 13 12 11 10 07 06 05 04 03 02 01 ....
  • Page 65 Chapter 6 Interpreting Module to PLC Data (READS) Figure 6.3 Status Word 1 15 14 13 12 11 10 07 06 05 04 03 02 01 ....
  • Page 66 Chapter 6 Interpreting Module to PLC Data (READS) Bit 4 – Auto Mode The auto mode bit turns on when the loop is in auto mode, i.e., when the auto/manual bit in the command block is on and the auto/manual hardware input is true.
  • Page 67 Chapter 6 Interpreting Module to PLC Data (READS) Bit 10 – Start The start bit reflects the state of the hardware start input (0 = no start, 1 = start). Bit 11 – Stop The stop bit reflects the state of the hardware stop input (0 = stop, 1 = no stop). Important: The hardware stop is a low-true signal.
  • Page 68 Chapter 6 Interpreting Module to PLC Data (READS) Status Word 2 (words 3 and 7) Status word 2 gives the active setpoint and provides additional status information. Figure 6.4 Status Word 2 15 14 13 12 11 10 08 07 06 05 04 03 02 01 .
  • Page 69 Chapter 6 Interpreting Module to PLC Data (READS) Bit 6 – Position Valid The position valid bit is on if the next two status block words (i.e., words 4 and 5 for axis 1 and words 8 and 9 for axis 2) contain a valid axis position. Bit 7 –...
  • Page 70 Chapter 6 Interpreting Module to PLC Data (READS) Bit 13 – Feedback Fault The feedback fault bit turns on when the module detects a fault in the transducer interface circuitry. In this event, the module also activates OUTPUT 2 if configured as the loop fault output.
  • Page 71 Chapter 6 Interpreting Module to PLC Data (READS) Diagnostic Information (words 4, 5 and 8, 9) After a reset command or powerup, the module displays diagnostic information so you can detect parameter block errors. (The module doesn’t accept command blocks until after it receives a valid parameter block.) Use the diagnostic words to determine the cause of a block transfer error.
  • Page 72 Chapter 6 Interpreting Module to PLC Data (READS) Table 6.A Error Codes Code Definition No errors detected Invalid block identifier Non BCD number entered Invalid bit setting, unused bits must be set to zero Data is out of range Invalid number of axes programmed Setpoint is not defined Setpoint commanded while in manual mode Position exceeds a software travel limit...
  • Page 73 Chapter 6 Interpreting Module to PLC Data (READS) Figure 6.6 Position Format 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ....
  • Page 74 Chapter 6 Interpreting Module to PLC Data (READS) Figure 6.7 Following Error Format 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ....
  • Page 75 Chapter 6 Interpreting Module to PLC Data (READS) Measured Velocity (words 20 and 21) Measured velocity is the instantaneous speed of the axis measured at the transducer. This velocity is calculated using a moving average over the previous 20, 50 or 100 milliseconds (depending on the velocity commanded for the move).
  • Page 76 Chapter 6 Interpreting Module to PLC Data (READS) Figure 6.10 Desired Velocity Format 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ....
  • Page 77 Chapter 6 Interpreting Module to PLC Data (READS) Figure 6.12 Desired Deceleration Format 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ....
  • Page 78 Chapter 6 Interpreting Module to PLC Data (READS) Maximum Velocity (words 30, 31 and 32, 33) The maximum velocity words represent the maximum speed that the system is capable of moving in each direction, and not necessarily the maximum velocity of a particular move.
  • Page 79 Chapter 6 Interpreting Module to PLC Data (READS) the accuracy is degraded if the axis is unstable or if the velocity is extremely low. Velocities at or above 10% of the maximum velocity work best. the maximum velocities calculated by the module will not be accurate if motion is impeded by physical obstructions.
  • Page 80 Chapter Formatting Module Data (WRITES) Data Blocks Used in Write Data blocks that you set up in the PLC data table enable you to control the Operations module from your PLC programs. There are four types of data blocks used in write operations.
  • Page 81 Chapter 7 Figure 7.1 Parameter Block Word Assignments WORD 50057...
  • Page 82 Chapter 7 Parameter Control Word (word 1) The parameter control word identifies the block as a parameter block and provides configuration information common to both loops. You can also disable the transducer interface, analog outputs, and discrete inputs by setting the appropriate bits.
  • Page 83 Chapter 7 Bit 3 – Binary/BCD Bit 3 determines the format of the data contained in block transfer reads and writes. BCD format provides compatibility with older programmable controllers. Binary format provides compatibility with the PLC-5, which uses integer (16-bit 2’s complement) data. Bit 4 –...
  • Page 84 Chapter 7 Bit 7 – Binary Position Format When bit 7 is set to 1, and binary format is specified in the parameter control word (bit 3 = 0), the module can display position and error values between -32.768 and 32.767 inches (-327.68 and 327.67 mm) in the second word of the position or following error in the status block.
  • Page 85 Chapter 7 Important: If the maximum analog range is negative, the +ANALOG and –ANALOG outputs behave as if they were physically reversed. ATTENTION: An incorrect sign for the analog range can cause the axis to accelerate out of position when you close the loop. Figure 7.3 Analog Range Word 50058...
  • Page 86 Chapter 7 Figure 7.4 Analog Calibration Constant Words 50027 For servo valves, the analog calibration constants can be roughly calculated from the diameter of the cylinder and the maximum flow rate of the valve. You will fine-tune these parameters when you perform the tuning procedure given in Chapter 8.
  • Page 87 Chapter 7 Figure 7.5 Transducer Calibration Constant Words 50028 Zero Position Offset (words 7, 8 and 36, 37) The zero position offset words define the origin of the coordinate system. Zero-position can be located within or outside the transducer’s active range. This allows positions to be measured relative to locations outside the range of axis motion.
  • Page 88 Chapter 7 Important: If you change the axis polarity, exchange the forward and reverse analog calibration constants. The zero-position offset defines the direction of forward and reverse motion. Calculate the zero-position offset by measuring the distance between the zero-position and the transducer’s head, as shown above. The module accepts a maximum of +799.900 inches (+7999.00 millimeters).
  • Page 89 Chapter 7 If you program both software travel limits to zero, the module defaults to a negative software travel limit of 0 and a maximum positive software travel limit that is 180.0 inches or 4572 mm for one recirculation. If you select binary format, the software travel limits are represented as 2’s-complement integers.
  • Page 90 Chapter 7 If the zero-position and software travel limits are 0, all measurements are relative to the transducer head and the positive direction is towards the end of the transducer. If you program both software travel limits to 0, the module defaults to the maximum and minimum that it can measure.
  • Page 91 Chapter 7 In this example, the polarity of the axis has been reversed. The positive direction is now towards the transducer head as indicated by the sign of the zero position offset. Notice that the software travel limit in the positive direction can have a negative sign.
  • Page 92 Chapter 7 The next two examples show the origin past the fully extended position. Figure 7.13 Zero Position Past the End of the Transducer Head 50017 50018 In Position Band (words 11 and 40) The in-position band is the area around an endpoint where the in-position bit turns on.
  • Page 93 Chapter 7 If you leave the in-position band undefined (at zero), the module automatically defaults to twice the value of the position resolution. For one circulation, this would be 0.004 inches. Figure 7.15 In Position Band Word 50006 PID Band (words 12 and 41) If the axis is within the PID band and the desired velocity is zero, the module enables the integral and derivative components for final positioning of the axis.
  • Page 94 Chapter 7 Figure 7.17 PID Band Word 50065 Deadband (words 13 and 42) The deadband parameter lets you select an error range on either side of a commanded endpoint where the integral term of the PID algorithm doesn’t change. Figure 7.18 Deadband 50064 The module uses the deadband only after the axis crosses the endpoint.
  • Page 95 Chapter 7 Excess Following Error (words 14 and 43) The excess following error is the maximum allowable axis error above the expected following error at the programmed velocity for the current move. The expected following error for a given velocity equals the velocity divided by the proportional gain.
  • Page 96 Chapter 7 Figure 7.21 Maximum PID Error Word 50005 The maximum value of this word is 9.999 inches or 99.99 mm. The maximum PID error must not be within the PID band unless the PID error checking is disabled. To disable PID error checking, specify zero. ATTENTION: To guard against equipment damage, we recommend that you exercise extreme care when operating an axis with PID error checking disabled.
  • Page 97 Chapter 7 Proportional Gain (words 17 and 46) The module uses the proportional gain factor K at axis speeds below the gain break speed. Figure 7.23 Proportional Gain Word 50023 The proportional gain is defined as the ratio of the axis speed divided by the positioning error (or following error): proportional gain = axis speed/positioning error Proportional gain effects axis response to positioning commands.
  • Page 98 Chapter 7 If gain is relatively high, following error will be relatively small, because the system will be more sensitive to changes in following error. If gain is low, following error becomes relatively larger, because the system is not as responsive to changes in following error.
  • Page 99 Chapter 7 Figure 7.26 Gain Break Plot 50069 Typically, at axis speeds below the gain break velocity, you would use a relatively high gain to allow precise axis positioning. By reducing the gain at axis speeds above the gain break speed, we can achieve better stability in some applications.
  • Page 100 Chapter 7 Figure 7.27 Gain Factor Word 50070 The gain factor must be less than 10.0. If you set it to zero, the proportional gain won’t be reduced or increased at any axis speed. Example: To increase a proportional gain to 0.5 from 0.1 at speeds above the gain break speed: gain factor = desired gain/proportional gain = 0.5/0.1...
  • Page 101 Chapter 7 The integral term alters response to positioning errors. If the integral gain is relatively high, the system will be more sensitive to positioning errors. However, if the gain is too high, the axis may overshoot and oscillate around programmed endpoints.
  • Page 102 Chapter 7 Figure 7.30 Feedforward Gain Word 50073 Without feedforwarding axis motion does not begin until the following error is large enough to overcome friction and inertia. The feedforward component generates a velocity command to move the cylinder almost immediately. This immediate response keeps the actual position closer to the desired position and thereby reduces the following error.
  • Page 103 Chapter 7 Global Acceleration/Deceleration (words 24, 25 and 53, 54) This parameter specifies the acceleration and deceleration rate the module uses for all jogs and for those setpoint and motion segment moves that do not use local acceleration and deceleration rates. The deceleration value is also used for executing slide stops during manual mode.
  • Page 104 Chapter 7 The velocity smoothing constant determines how quickly the system will change its acceleration and deceleration. The higher the value, the more quickly acceleration and deceleration will change. A higher, faster value produces jerkier motion, while a lower, slower value produces a smoother transition. The following diagrams demonstrate the effect of the velocity smoothing constant.
  • Page 105 Chapter 7 Figure 7.35 Higher Velocity Smoothing Constant 50020 Jog Rate (Low and High) (words 27, 28 and 56, 57) The jog rate words define the low and high speeds for software and hardware initiated jogs in either direction. By setting the jog rate select bit in the command block, you select high or low jog rate.
  • Page 106 Chapter 7 Figure 7.36 Jog Rate (Low and High) Words 50077 Important: The low jog rate must be lower than or equal to the high jog rate. Both rates must be lower than the greatest of either maximum velocity, as specified by the analog calibration constants.
  • Page 107 Chapter 7 Figure 7.37 Setpoint Block Word Assignments 50078 The module internally maintains information on each of the 12 setpoints controlled by the setpoint block. On powerup or after a reset command each of these internal setpoints is disabled. The programmable controller must redefine one or all of these setpoints through the setpoint block.
  • Page 108 Chapter 7 Setpoint Block Control Word (word 1) The setpoint block control word identifies the block as a setpoint block, specifies the axis or axes for which the setpoints are intended, and indicates the number of setpoints defined in the block. Figure 7.38 Setpoint Block Control Word 5007...
  • Page 109 Chapter 7 Example: If the axis is stationary at +1 inch (from the zero-position offset), an absolute setpoint move with a position value of 2 inches will move the actuator 1 inch to the +2 inch position. An incremental setpoint move with a position value of 2 inches will move the actuator 2 inches to the +3 inch position.
  • Page 110 Chapter 7 Figure 7.40 Setpoint Position Words 50081 Important: If you select binary format, both words are represented as 2’s-complement integers compatible with the PLC-5. See Appendix H for examples of these words. Local Velocity The local velocity word defines the velocity you want for the corresponding setpoint move.
  • Page 111 Chapter 7 Local Acceleration/Deceleration The local acceleration and deceleration words define the acceleration and deceleration you want for the corresponding setpoint move. You can disable either or both of these parameters by setting them to zero. The module will then use the global parameter.
  • Page 112 Chapter 7 Figure 7.43 Command Block Word Assignments WORD 50085 Axis Control Word 1 (words 1 and 8) The structure of axis control word 1 is shown below: Figure 7.44 Axis Control Word 1 50086...
  • Page 113 Chapter 7 Bit 0 – Start Bit 0 in the first axis control word is the start bit. The transition of this bit from low to high (0 to 1) signals a software start command. Upon receiving this command, the module begins the setpoint or motion segment move specified in axis control word 2.
  • Page 114 Chapter 7 Bit 1 – Hardware Start Enable Bit 1 in the first axis control word is the hardware start enable bit. Setting this bit enables the hardware start input. If this bit is reset, the loop ignores hardware start commands. Note that the discrete inputs must also be enabled by the parameter block before the module will recognize hardware start inputs.
  • Page 115 Chapter 7 On = high jog rate If this bit changes state during a jog operation, the axis will accelerate or decelerate to the newly commanded rate at the global acceleration/deceleration rate programmed in the parameter block. Bits 5 and 6 – Forward Jog and Reverse Jog Turning on bit 5 causes axis motion in the forward direction.
  • Page 116 Chapter 7 Bit 8 – Immediate Stop Setting the immediate stop bit causes the module to immediately set the analog output to zero and turn on OUTPUT 2 if it is configured as the loop fault output. To recover from an immediate stop condition, either issue a reset command or turn the I/O chassis power off and then back on.
  • Page 117 Chapter 7 Bits 12 and 13 – Readout Select Bits 12 and 13 are the readout select bits. The third and fourth status words for an axis provide either current axis position, following error, or diagnostic information. The readout select bits determine which information is displayed in the status block.
  • Page 118 Chapter 7 Bits 7 to 15 – Reserved Bits 7 to 15 are reserved for future use. The programmable controller program must set them to zero. Setpoint 13 Words (words 3 to 7 and 10 to 14) The setpoint 13 words control position, velocity, acceleration, and deceleration for setpoint 13.
  • Page 119 Chapter Initializing and Tuning the Axes Before you load an application ladder logic program into the programmable controller, you should follow the procedures in this chapter to initialize and tune the movement of each axis. A simple ladder logic program, QB_SETUP, provided on the accompanying disk, is intended to simplify the initial integration process.
  • Page 120 Chapter 8 Adjusting the Servo Valve The first step in initializing the module is to adjust the null on each servo valve. Nulls To do so, carry out the following steps: Turn off axis power. Disconnect the servo valve from the module. Start the hydraulic pump and check the system pressure.
  • Page 121 Chapter 8 Table 8.A Default Parameter Block Settings Parameter Suggested Values Comments Metric Make sure that you have set the analog configuration switches correctly and that you have entered the correct range into the parameter block. ATTENTION: Incorrect analog output configuration can cause sudden high-speed motion.
  • Page 122 Chapter 8 Figure 8.1 Parameter Block Data Table QB_SETUP - Axis 1 Parameter Description Data Table Address Position File Data N45:1...
  • Page 123 Chapter 8 Figure 8.2 Command Block Data Table QB_SETUP - Axis 1 Command Description Data Table Address Position File Data N45: 131...
  • Page 124 Chapter 8 Figure 8.3 Program Rungs for QB_SETUP...
  • Page 125 Chapter 8 Verifying Analog Output You should verify the analog output polarity using low speed open-loop jogs as Polarity follows: ATTENTION: Incorrect analog output polarity will cause the axis to accelerate out of position when then loop is closed. The analog output polarity is affected by both the wiring on terminals 29/31 and the sign of the analog range in the parameter block.
  • Page 126 Chapter 8 Table 8.B Transducer Calibration Number of Transducer Calibration Constant Circulations Microsec/Inch Microsec/mm Enter the transducer calibration constant from the table into the parameter block for the axis. Send the new parameter block to the module. With the hydraulic pump off, mark the position of the axis relative to a stationary structure.
  • Page 127 Chapter 8 Record the new axis position value from the module. This value is in the status block words 12 and 13 at N44:12 and N44:13 for axis 1. Subtract the initial axis position from the new axis position and record this as the module distance.
  • Page 128 Chapter 8 Axis Tuning Each axis needs to be tuned to allow for its specific mechanical and electrical characteristics. If you change system variables, such as hydraulic pressure, cylinder size or servo valve characteristics, you may need to re-tune your axis as well.
  • Page 129 Chapter 8 If you have a cylinder with a 2 inch bore (inside diameter) and a servo valve rated for 10 gallons per minute, the maximum velocity is approximated as follows: Velocity = 4.9 x 10/2 = 12.25 ips Use bits 5 and 6 of axis control word 1 (N45:131) to jog the axis back and forth between the software travel limits until the maximum velocity stabilizes in the status block.
  • Page 130 Chapter 8 Initialize the loop gains as follows: Proportional gain: = 0.0050 ips/mil Integral gain: Derivative gain: Feedforward gain = 20.0% Initiate a move using setpoint or jog commands. Increase the feedforward gain until the axis begins to overshoot, i.e., to exceed the desired end position.
  • Page 131 Chapter 8 Set the integral gain equal to 70% of the proportional gain at which continuous oscillations occurred (see step 3). = 0.7 x K Set the derivative gain equal to 70% of the proportional gain at which continuous oscillations occurred (see step 3). This small derivative gain is recommended to improve axis stability.
  • Page 132 Chapter Advanced Features The advanced features of the Linear Positioning Module enable you to create complex movement profiles, synchronize multiple axes, and perform cam-emulation. They are not required in order to use the module, and should only be used once you fully understand how to initiate and control motion using setpoints.
  • Page 133 Chapter 9 Advanced Features Important: All segments in a motion block, and the programmable I/O word, become valid as soon as they are downloaded to the module. The one exception is a downloaded segment corresponding to the currently active motion segment. In that case, the active segment must complete its profile or meet its trigger conditions before the new segment becomes valid.
  • Page 134 Chapter 9 Advanced Features Figure 9.2 illustrates a motion profile consisting of five motion segments. Segments 14 through 17 move the axis in one direction, while segment 18 returns it to its original position and triggers segment 14. The solid line indicates the actual axis movement and the dotted lines show the profile of each motion segment if its motion were not interrupted by the triggering of the subsequent motion segment.
  • Page 135 Chapter 9 Advanced Features Motion Block Control Word The motion block control word identifies the block as a motion block, specifies the number of motion segments defined in the block, and indicates whether or not it contains a programmable I/O control word. (See Figure 9.3.) Nineteen motion blocks must be downloaded to the module to configure all 114 motion segments.
  • Page 136 Chapter 9 Advanced Features Programmable Input and You can configure the general purpose inputs, INPUT 1 and/or INPUT 2 so Output that, given their state and the trigger conditions in the current segment, another motion segment may be triggered. Also, any motion segment may optionally pulse or latch the programmable outputs, OUTPUT 1 and OUTPUT 2, when the trigger conditions are satisfied.
  • Page 137 Chapter 9 Advanced Features low for the specified duration when triggered to pulse When an output changes to a high or low state, it is guaranteed to stay in that state for a minimum of 16 milliseconds in order to be compatible with the discrete inputs.
  • Page 138 Chapter 9 Advanced Features Bit 7 - Normal/Complement OUTPUT 2 If OUTPUT 2 is configured to be programmable, this bit defines whether OUTPUT 2 is normal (active high) or complement (active low). See the description for bit 3 of this word. Bit 8 - Outputs Reset/Fault State This bit indicates whether OUTPUT 1 and OUTPUT 2 (when configured as programmable outputs) remain in their last state or are reset when:...
  • Page 139 Chapter 9 Advanced Features Default I/O Configuration If you do not download the programmable I/O control word, the module defaults both axes to: INPUT 1 positive edge trigger INPUT 2 high level trigger OUTPUT 1 in-position output OUTPUT 2 loop fault output Motion Segments A motion segment consists of a setpoint, trigger conditions, and programmable output options.
  • Page 140 Chapter 9 Advanced Features Figure 9.5 Motion Segment Control Words 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ....
  • Page 141 Chapter 9 Advanced Features Control Word 2: Bits 4 and 5 - Velocity/Position Trigger These bits indicate if one of the velocity, relative position, or absolute position triggers is active. If the velocity trigger is active, you must specify in the trigger velocity/position word, the absolute velocity at which the trigger condition will be satisfied.
  • Page 142 Chapter 9 Advanced Features Desired Position, Local Velocity, Local Acceleration and Local Deceleration Words The format of the (MS) desired position, (LS) desired position, local velocity, local acceleration and local deceleration words in the motion block (see Figure 9.1) is the same as the format of the (MS) setpoint position, (LS) setpoint position, local velocity and local deceleration words in the setpoint block.
  • Page 143 Chapter 9 Advanced Features Using the Motion Block As mentioned previously, because initiating a single motion segment from the command block can trigger a sequence of motions, you must exercise caution when using the motion block. For safety reasons, a watchdog monitors the state of the programmable controller.
  • Page 144 Chapter 9 Advanced Features Important: Incremental motion segments and relative position triggers are based on the current axis position at the beginning of the motion segment’s execution. Because of this, if you link a series of incremental motion segments together you will likely see a small build-up of error. It is recommended that an absolute position move be done occasionally to remove this error build-up.
  • Page 145 Chapter Sample Application Programs This chapter gives a general explanation of how to program programmable logic controllers and provides the code for, and descriptions of, the two sample application programs contained on the disk that accompanies the Linear Positioning Module. Application Program 1 shows how to implement axis movement for a single axis using a setpoint block containing four setpoints.
  • Page 146 Chapter 10 Sample Application Programs Figure 10.1 Overview of Block Transfers 1771-QB Data Table Module Block Transfer Read Status Status Block Block Parameter Parameter Block Block Setpoint Setpoint Block(s) Block(s) Block Transfer Write Motion Motion Block(s) Block(s) Command Command Block Block 50100 Block Transfer Sequencing...
  • Page 147 Chapter 10 Sample Application Programs PLC 5 Block Transfer You should program a PLC-5 processor’s block transfer to use the bidirectional Instructions method to avoid problems when troubleshooting the module. However, block transfer writes only need to be enabled when a command block, motion blocks, setpoint blocks or a parameter block must be sent to the module.
  • Page 148 Chapter 10 Sample Application Programs Important: Note that: the program doesn’t issue the start command for each move until after the module reports in-position (through the status block) from the previous move due to the specified deceleration rate of move 3, the axis will not achieve the final rate of 5 in/s Figure 10.3 Movement Profile for Application Program #1...
  • Page 149 Chapter 10 Sample Application Programs Planning the Data Blocks for Application Program #1 For this example, we assume a PLC-5/15 controller and assign the data blocks shown in Table 10.A. The files used are shown in Table 10.B. Table 10.A Data Blocks for Application Program #1 Block Starting Addres...
  • Page 150 Chapter 10 Sample Application Programs Figure 10.4 Data Table Contents for Application Program #1 Parameter Block Project Name: Page Application Program #1 - Axis 1 Designer: Address Date: Axis No. Block Description: Parameter Description Data Table Address Position File Data Parameter control word (Axis 1, inches, BCD) N45:1 Analog range (100%)
  • Page 151 Chapter 10 Sample Application Programs Figure 10.5 Data Table Contents for Application Program #1 Setpoint Block Project Name: Page Application Program #1 - Axis 1 Designer: Address Date: Axis No. Block Description: Setpoint Description Data Table Address Position File Data Setpoint block control word (Axis 1, 4 setpoints) N45:61 Incremental/absolute word (all absolute)
  • Page 152 Chapter 10 Sample Application Programs Figure 10.6 Data Table Contents for Application Program #1 Command Block Project Name: Page Application Progam #1 - Axis 1 Designer: Address Date: Axis No. Block Description: Command Description Data Table Address Position File Data Axis control word 1 (Diagnostic, auto) N45: 131 Axis control word 2...
  • Page 153 Chapter 10 Sample Application Programs Rung 2:1 Rungs 2:1, 2:2, and 2:3 determine which block (parameter, setpoint, or command) will be sent to the module via the next block transfer write (BTW). If the axis 1 ready bit is low, (the module is in powerup or a reset command has just been executed), rung 2:1 moves the source address of the parameter block into the BTW’s control block.
  • Page 154 Chapter 10 Sample Application Programs Figure 10.8 Program Rungs for Application Program #1 Rung 2:0 ENABLE ENABLE N7:0 N7:5 BLOCK TRNSFR READ ( EN ) ] / [ ] / [ Rack Group ( DN ) Module Control Block N7:0 ( ER ) Data file N44:1...
  • Page 155 Chapter 10 Sample Application Programs Application Program #2 This application program illustrates how to use a module to control the motion of a single axis using motion blocks. (See Chapter 9.) Figure 10.9 shows the movement profile for this program. Five motion segments describe axis movement.
  • Page 156 Chapter 10 Sample Application Programs Important: Note that: due to the specified acceleration and deceleration rate of move #14, the axis will not achieve the final velocity rate of 5 in/s because moves #16 and #17 have discrete input triggers which may be triggered at any time during their movements profiles, the axis may not achieve the final velocity rates of 2 in/s and 3 in/s all motion segments and programmable I/O information could be contained...
  • Page 157 Chapter 10 Sample Application Programs Figure 10.10 to Figure 10.14 show the hexadecimal values for the motion and command blocks, and necessary sequencer data for this example. Figure 10.10 Data Table Contents for Application Program #2 Motion Block 1 Project Name: Page Application Program #2 - Axis 1 Designer:...
  • Page 158 Chapter 10 Sample Application Programs Figure 10.11 Data Table Contents for Application Program #2 Motion Block 2 Project Name: Page Application Program #2 - Axis 1 Designer: Address Date: Axis No. Block Description: Motion Block 2 Description Data Table Address Position File Data Motion block control word (2 motion segments)
  • Page 159 Chapter 10 Sample Application Programs Figure 10.13 Data Table Contents for Application Program #2 Command Block Project Name: Page Application Progam #2 – Axis 1 Designer: Address Date: Axis No. Block Description: Command Description Data Table Address Position File Data Axis control word 1 (diagnostic, auto, start) N45:131 Axis control word 2 (motion segment #16)
  • Page 160 Chapter 10 Sample Application Programs Program Rungs for Application Program #2 Figure 10.15 and Figure 10.16 show the ladder diagram programming for this application on a PLC-5/15 system. The rungs perform the following functions: Rung 2:0 Rung 2:0 reads the module’s status block and, in conjunction with rung 2:5, performs bidirectional block transfers to and from the module.
  • Page 161 Chapter 10 Sample Application Programs Figure 10.15 Program Rungs for Application Program # 2 Rung 2:0 ENABLE ENABLE N7:0 N7:5 BLOCK TRNSFR READ ( EN ) ] / [ ] / [ Rack Group ( DN ) Module Control Block N7:0 ( ER ) Data file...
  • Page 162 Chapter 10 Sample Application Programs Figure 10.16 Program Rungs for Application Program # 2 (continued) Rung 2:4 AXIS 1 MOTION AXIS 1 BLOCKS READY LOADED ELEMENT # N44:2 R6:2 MOVE Source Dest N7:9 FILE # MOVE Source Dest N7:8 Rung 2:5 ENABLE ENABLE N7:0...
  • Page 163 Chapter Troubleshooting The module transfers diagnostic information to the programmable controller in the status block. In addition, the module displays fault information for each loop on the status indicators. Unless the module loses backplane power, all fault conditions cause the fault indicator to turn on. Use the module’s indicators and the status block to diagnose and remedy module faults and errors.
  • Page 164 Chapter 11 Troubleshooting Module Fault Indicator This red indicator is normally off. It turns on if there is a module fault in one loop or both loops. Faults may be caused by: loss of analog power analog interface fault memory fault discrete input fault transducer interface fault excess following error...
  • Page 165 Chapter 11 Troubleshooting Table 11.A Troubleshooting Indicators Indication Description Probable Cause Recommended Action Fault Normal Condition Module is fully functional. Loop 1 Loop 2 Fault Power Up State A) Powerup complete, awaiting initial A) Send parameter block, monitor status Loop 1 parameter block.
  • Page 166 Chapter 11 Troubleshooting Connect the -GATE terminal (3/4) to the -INTERR terminal (7/8). Power up the axis and check the status block for feedback faults. If you still experience feedback faults, make sure that your transducer power supply is providing +5 VDC (+5%) through terminals 9 and 10 on the module’s wiring arm.
  • Page 167 Chapter 11 Troubleshooting Figure 11.2 Troubleshooting Flowchart START Consult PLC Processor Assembly and Installation Indicator? Manual adapter Consult PLC ACTIVE Installation Manual Indicator Check the module's Indicators. Power up the I/O chassis containing the module. Return the Module module for repair if the Fault fault indicator remains lit when you restore...
  • Page 168 Chapter 11 Troubleshooting Figure 11.2 Troubleshooting Flowchart (Continued) Check diagnostic Programming word(s) to determine Error the cause of the programming error. Faults indicated by Take appropriate 2nd status corrective action. word(s) 1. Check PLC program to ensure that a parameter block was sent.
  • Page 169 Chapter 11 Troubleshooting Figure 11.2 Troubleshooting Flowchart (Continued) Establish auto mode. Execute a move to each setpoint. 1. Check for active stop or reset commands. 2. Re check for errors in status block. Moves executed 3. Check setpoint's correctly position, velocity, acceleration and deceleration.
  • Page 170 Appendix Glossary of Terms & Abbreviations Absolute Position: A position described by its distance from the zero point of a coordinate axis. Acceleration: The rate at which the speed of axis motion increases. Adapter Module: A module that provides communication between an I/O chassis and the programmable controller.
  • Page 171 Appendix A Glossary of Terms & Abbreviations Circulations: A digital process that involves re-triggering an interrogation pulse a fixed number of times by the return pulse, to provide more counting time for digital counter circuitry, thus improving resolution from a linear displacement transducer system. The on time of the digital interface electronics pulse duration output is multiplied by a specified factor.
  • Page 172 Appendix A Glossary of Terms & Abbreviations Feedback Resolution: The smallest increment of dimension that the feedback device can distinguish and reproduce as an electrical output. Feedback Signal: The measurement signal indicating the value of a directly controlled variable, which is compared to a commanded value to obtain the corrective error signal.
  • Page 173 Appendix A Glossary of Terms & Abbreviations LS: Least significant (word, byte, or bit). mA: Milliamperes, a unit of measurement for electric current. Memory: A group of circuit elements that can store data. Millisecond (ms): One thousandth of a second. Module: A unit of a larger assembly.
  • Page 174 Appendix A Glossary of Terms & Abbreviations Reverse Motion: Axis movement in a negative direction along a coordinate axis. rms: Root mean square. Servo Valve: A hydraulic valve assembly capable of controlling the linear movement of a tool or workpiece. Setpoint: A pre-defined position on the axis.
  • Page 175 Appendix Status Block Figure B.1 Status Block Word Assignments WORD DESCRIPTION AXIS 1 AXIS 2 Module Configuration Word Status word 1 Default Status Status word 2 (MS) Position/Error/Diagnostic word (LS) Position/Error/Diagnostic word (11) Active motion segment/setpoint (14) (MS) Position (15) (LS) Position (18) (MS) Following Error...
  • Page 176 Appendix B Status Block Figure B.2 Module Configuration Word (word 1) 15 14 13 12 11 10 07 06 05 04 03 02 01 ....
  • Page 177 Appendix B Status Block Figure B.4 Status Word 2 (words 3 and 7) 15 14 13 12 11 10 08 07 06 05 04 03 02 01 ....
  • Page 178 Appendix B Status Block Figure B.6 Position/Error/Diagnostic Words (words 4, 5; 8, 9; 12, 13; and 14, 15) Position Format 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ..
  • Page 179 Appendix B Status Block Figure B.8 Active Motion Segment/Setpoint (words 10 and 11) 15 14 13 12 11 10 07 06 05 04 03 02 01 ....
  • Page 180 Appendix B Status Block Figure B.11 Desired Acceleration (words 24 and 25) 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ....
  • Page 181 Appendix B Status Block Figure B.14 Maximum Velocity (words 30, 31 and 32, 33) 15 14 13 12 11 10 08 07 06 05 04 03 02 01 00 ... . .
  • Page 182 Appendix B Status Block Table B.A Error Codes Code Definition No errors detected Invalid block identifier Non BCD number entered Invalid bit setting, unused bits must be set to zero Data is out of range Invalid number of axes programmed Setpoint is not defined Setpoint commanded while in manual mode Position exceeds a software overtravel limit...
  • Page 183 Appendix Parameter Block Figure C.1 Parameter Block Word Assignments WORD 50057...
  • Page 184 Appendix C Figure C.2 Parameter Block Control Word (word 1) 50001 Figure C.3 Analog Range Word (words 2 and 31) 50058...
  • Page 185 Appendix C Figure C.4 Analog Calibration Constant Words (words 3, 4 and 32, 33) 50027 Figure C.5 Transducer Calibration Constant Words (words 5, 6 and 34, 35) 50028...
  • Page 186 Appendix C Figure C.6 Zero Position Offset Words (words 7, 8 and 36, 37) 50029 Figure C.7 Software Travel Limit Words (words 9, 10 and 38, 39) 50061...
  • Page 187 Appendix C Figure C.8 In Position Band Word (words 11 and 40) 50006 Figure C.9 PID Band Word (words 12 and 41) 50065 Figure C.10 Deadband Word (words 13 and 42) 50066 Figure C.11 Excess Following Error Word (words 14 and 43) 50022...
  • Page 188 Appendix C Figure C.12 Maximum PID Error Word (words 15 and 44) 50005 Figure C.13 Integral Term Limit Word (words 16 and 45) 50067 Figure C.14 Proportional Gain Word (words 17 and 46) 50023...
  • Page 189 Appendix C Figure C.15 Gain Break Speed Word (words 18 and 47) 50011 Figure C.16 Gain Factor Word (words 19 and 48) 50070 Figure C.17 Integral Gain Word (words 20 and 49) 50071...
  • Page 190 Appendix C Figure C.18 Derivative Gain Word (words 21 and 50) 50072 Figure C.19 Feedforward Gain Word (words 22 and 51) 50073 Figure C.20 Global Velocity Word (words 23 and 52) 50074...
  • Page 191 Appendix C Figure C.21 Global Acceleration/Deceleration Words (words 24, 25 and 53, 54) 50076 Figure C.22 Velocity Smoothing (Jerk) Constant Word (words 26 and 55) 50075...
  • Page 192 Appendix C Figure C.23 Jog Rate (Low and High) Words (words 27, 28 and 56, 57) 50077...
  • Page 193 Appendix C Table C.A Parameter Block Values Parameter Limits...
  • Page 194 Appendix Setpoint Block Figure D.1 Setpoint Block Word Assignments Setpoint block control word Incremental/absolute word (MS) Setpoint position (LS) Setpoint position Move #1 Local velocity Local acceleration Local deceleration Up to (MS) Setpoint position (LS) Setpoint position Move #2 Local velocity words Local acceleration Local deceleration...
  • Page 195 Appendix D Setpoint Block Figure D.3 Incremental/Absolute Word (word 2) 15 14 13 12 11 10 08 07 06 05 04 03 02 01 00 ....
  • Page 196 Appendix D Setpoint Block Figure D.6 Local Acceleration/Deceleration Words 15 14 13 12 11 10 08 07 06 05 04 03 02 01 00 ....
  • Page 197 Appendix Command Block Figure E.1 Command Block Word Assignments WORD Axis control word 1 Axis control word 2 (MS) Setpoint 13 position Axis 1 (LS) Setpoint 13 position Setpoint 13 velocity Setpoint 13 acceleration Setpoint 13 deceleration Axis control word 1 Axis control word 2 (MS) Setpoint 13 position Axis 2...
  • Page 198 Appendix E Command Block Figure E.2 Axis Control Word 1 (words 1 and 8) 15 14 13 12 11 10 08 07 06 05 04 03 02 01 ... . .
  • Page 199 Appendix E Command Block Figure E.4 Setpoint 13 Position Words (words 3, 4 and 10, 11) 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ... . .
  • Page 200 Appendix E Command Block Figure E.6 Setpoint 13 Local Acceleration/Deceleration Words (words 6, 7 and 13, 14) 15 14 13 12 11 10 08 07 06 05 04 03 02 01 00 ..
  • Page 201 Appendix Motion Block Figure F.1 Motion Block Word Assignments Motion block control word Motion segment control word 1 Motion segment control word 2 (MS) Desired position (LS) Desired position 1st motion Local velocity segment Local acceleration Local deceleration Trigger velocity or (MS) trigger position (LS) Trigger position Motion segment control word 1 Motion segment control word 2...
  • Page 202 Appendix F Motion Block Figure F.2 Motion Block Control Word 15 14 13 12 11 10 08 07 06 05 04 03 02 01 ....
  • Page 203 Appendix F Motion Block Figure F.4 Motion Segment Control Words 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ....
  • Page 204 Appendix F Motion Block Figure F.5 Desired/Trigger Position Words 15 14 13 12 11 10 07 06 05 04 03 02 01 00 ....
  • Page 205 Appendix F Motion Block Figure F.7 Local Acceleration/Deceleration Words 15 14 13 12 11 10 08 07 06 05 04 03 02 01 00 ....
  • Page 206 Appendix Hexadecimal Data Table Forms For your convenience, we have included data table forms for each type of block, and both axes, where applicable, on the following pages. Copy these forms and fill it in with hexadecimal values for the parameter, setpoint, motion and command blocks, and necessary sequencer data for your PLC programs.
  • Page 207 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Parameter Description Data Table Address Position File Data Parameter control word N45:1 Analog range + Analog calibration constant - Analog calibration constant (MS) Transducer calibration constant (LS) Transducer calibration constant (MS) Zero position offset (LS) Zero position offset...
  • Page 208 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Parameter Description Data Table Address Position File Data Analog range N45:31 + Analog calibration constant - Analog calibration constant (MS) Transducer calibration constant (LS) Transducer calibration constant (MS) Zero position offset (LS) Zero position offset + Software travel limit...
  • Page 209 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Setpoint Description Data Table Address Position File Data Setpoint block control word N45:61 Incremental/absolute word Move #1 (MS) Setpoint position (LS) Setpoint position Local velocity Local acceleration Local deceleration Move #2 (MS) Setpoint position...
  • Page 210 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Setpoint Description Data Table Address Position File Data Move #7 (MS) Setpoint position (LS) Setpoint position Local velocity Local acceleration Local deceleration Move #8 (MS) Setpoint position (LS) Setpoint position Local velocity Local acceleration...
  • Page 211 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Setpoint Description Data Table Address Position File Data Setpoint block control word N45:161 Incremental/absolute word Move #1 (MS) Setpoint position (LS) Setpoint position Local velocity Local acceleration Local deceleration Move #2 (MS) Setpoint position...
  • Page 212 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Setpoint Description Data Table Address Position File Data Move #7 (MS) Setpoint position (LS) Setpoint position Local velocity Local acceleration Local deceleration Move #8 (MS) Setpoint position (LS) Setpoint position Local velocity Local acceleration...
  • Page 213 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Motion Block Description Data Table Address Position File Data Motion block control word 50101...
  • Page 214 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Motion Block Description Data Table Address Position File Data 50101...
  • Page 215 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: 1 and 2 Command Description Data Table Address Position File Data Axis 1 Axis control word 1 N45:131 Axis control word 2 (MS) Setpoint 13 position (LS) Setpoint 13 position Setpoint 13 velocity Setpoint 13 acceleration...
  • Page 216 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Sequencer Data Description Data Table Address Position File Data D9:0 50104 G 11...
  • Page 217 Appendix G Hexadecimal Data Table Forms Project Name: Page Designer: Address Date: Axis No. Block Description: Description Data Table Address Position File Data 50104 G 12...
  • Page 218 Appendix Data Formats Bit 3 in the parameter control word (word 1 in the parameter block) determines the format of the data contained in block transfer reads and writes. BCD format provides compatibility with older programmable controllers. Binary format provides compatibility with the PLC-5, which uses integer (16-bit 2’s complement) data.
  • Page 219 Appendix H Data Formats Following are two methods to get the negative of a number using the 2’s complement method. Bit Inversion Method To get the 2’s complement of a number using the bit inversion method you must invert each bit from right to left after the first 1. Example: To represent -1524 (decimal) in 16-bit 2’s complement format, we start with the binary equivalent of the positive of the number.
  • Page 220 Appendix H Data Formats Example You want to program a global velocity of 1.50 inches/second for axis 1. This value has an implied decimal between the digits 1 and 5. The decimal point is implied because you don’t actually type it when you enter the value into the programmable controller data table.
  • Page 221 Appendix H Data Formats A sign bit is placed in each word to allow negative binary numbers even with the first word zeroed. Simply signing the first word in this case would not work in binary mode because a word with a value of zero and the sign bit on (i.e., a negative zero) is not equal to zero in the 16-bit 2’s complement system.
  • Page 222 Appendix Product Specifications Location Discrete Outputs 1771 Universal I/O chassis Single ended source One slot Logic 0: No voltage supplied to output (OFF state) Logic 1: User supplied voltage applied to output (ON state) Sampling Period Current: 2 milliseconds for both loops (i.e., both axis positions are read Maximum source drive 100 mA (ON state) simultaneously every 2 milliseconds) Maximum source leakage 1.0 mA (OFF state)
  • Page 223 Index Desired Velocity, Diagnostic Valid Bit, Absolute Positioning, 7 29 Diagnostic Words, Acceleration, 7 34 Error Codes, 6 10 Global, 7 24 Discrete Inputs Local, 7 32 Disabling, With Velocity Smoothing, 7 24 Enabling, Analog Calibration Constants, Fault, Analog Fault Bit, Power Supply, 5 14 Analog Outputs,...
  • Page 224 Index I–2 Hardware Stop Input, Motion Segment, Control Word, Desired Position Word, 9 11 Example, Local Acceleration Word, 9 11 Immediate Stop Bit, 7 37 Local Deceleration Word, 9 11 In Position Band, 7 13 Local Velocity Word, 9 11 In Position Bit, Inch/Metric Bit, Incremental Move 13 Bit,...
  • Page 225 Index I–3 Ready Bit, Interface Terminals, Power Supply, 5 11 Reset Bit, 7 37 Transducer Calibration Procedure, Reset Control, Trigger Condition, Trigger Conditions, Multiple, 9 10 Setpoint 13 Words, 7 39 Setpoint Block, Control Word, 7 28 Velocity Curve Smoothing, Setpoint Moves, Velocity Smoothing Constant, 7 24...
  • Page 226 Publication 1771-6.5.44, September 1993 PN 95592501 Supersedes 1771-6.5.44, August 1988 Copyright 1993 Allen-Bradley and Dynapro Systems Inc. Printed in Canada...