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Status Instruments DM4000U Manual

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52-314-2063-03
DM4000U
SMART
INDICATOR
Whilst every effort has been taken to ensure the accuracy of this document, we accept
no responsibility for damage, injury, loss or expense resulting from errors or
omissions, and reserve the right of amendment without notice.
This document is issued by Status Instruments Ltd and may not be reproduced in any
way without the prior written permission of the company.
Page 1
August 2003

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Summary of Contents for Status Instruments DM4000U

  • Page 1 This document is issued by Status Instruments Ltd and may not be reproduced in any way without the prior written permission of the company.

  • Page 2: Table Of Contents

    CONTENTS GETTING STARTED INTRODUCTION 3 - 5 UNPACKING INSTALLATION WIRING 7 - 24 USER GUIDE PROGRAMMING 25 - 67 OPERATION 68 - 73 Appendix A FITTING OF LEGEND ID Appendix B SPECIFICATION 75 - 79 Appendix C TROUBLESHOOTING 80 - 81 Appendix D MAINTENANCE Appendix E...

  • Page 3: Getting Started

    GETTING STARTED Page 3...

  • Page 4: Introduction

    1.0 INTRODUCTION This instrument is a universal digital indicator which supports a wide range of input types. A great advantage with this unit is its ability to adapt to a wide variety of applications. A comprehensive set of programming menus allow the instrument to be entirely re-configured from the keypad.
  • Page 5 The diagram of the rear panel below shows the slot positions for all electrical connections. There are two output slots into which the user may fit a range of options, including relays, current re-transmission and voltage output boards. In addition there is also a communications board slot allowing up to 30 units to be directly networked together to a host computer.

  • Page 6: Unpacking

    2.0 UNPACKING Please inspect the instrument carefully for signs of shipping damage. The packaging has been designed to afford maximum protection, however, we can not guarantee that undue mishandling will not have damaged the instrument. In the case of this unlikely event, please contact your supplier immediately and retain the packaging for our subsequent inspection.

  • Page 7: Installation

    INSTALLATION Page 7...
  • Page 8 SAFETY INFORMATION THIS SECTION FOR USE BY COMPETENT PERSONNEL ONLY • WARNING READ SAFETY INFORMATION BELOW BEFORE INSTALLATION • WARNING Hazardous voltages may be present on the terminals - the equipment must be installed by suitably qualified personnel and mounted on an enclosure providing protection to atleast IP20.
  • Page 9 MECHANICAL INSTALLATION When installing the instrument into the panel, the following dimensions should be taken into account. The unit is held in the Panel by two metal clamp bars, on diagonally opposite corners, fitted from the rear. A gasket is available, and should be fitted wherever sealing of the instrument is required.

  • Page 10: Wiring

    INSTALLATION 3.0 WIRING This section describes how the instrument should be wired for the Power Supply, Input Sensor or any Output options that may be fitted. All connections are made to three or five way sockets which are removable for ease of wiring. Installation should be undertaken in accordance with relevant sections of BS6739 - British Standards code of practice for "Instrumentation in Process Control Systems: Installation design and practice".
  • Page 11 INSTALLATION 3.2 WIRING PRECAUTIONS The unit can accept a variety of sensor inputs, some of which produce very small voltages. Therefore it is advisable to adhere to the following rules of good installation pratice. • Do not install close to switchgear, electromagnetic starters, contactors, power units or motors.
  • Page 12 INSTALLATION All sensor connections are summarised in the diagram below. 3.3.1 DC VOLTAGE INPUTS The unit has two individual voltage inputs. One supports millivolt inputs ( up to 100mV ), and the other, voltage inputs up to 10 volts. If the voltage input to be measured is to be no greater than 100mV it is connected to the millivolts input.
  • Page 13 INSTALLATION 3.2.1.2 VOLTAGE INPUT This input pin can take voltages up to 10 volts. The signal should be connected between pins 3 and 5 as indicated. 3.2.1.3 VOLTAGES GREATER THAN 10 VOLTS In order for these to be measured correctly, it is necessary to connect some simple external circuitry outside the unit to divide down the voltage to a nominal maximum of 10volts.
  • Page 14 INSTALLATION 3.2.2 CURRENT INPUTS There are two types of current measurement possible, the first type measures the current of an external loop, that is, a current that has been generated from an external power supply, or from another instrument. The second type measures current generated from the units own 20V excitation supply.
  • Page 15 INSTALLATION 3.3.3 THERMOCOUPLE INPUTS Thermocouples are simply connected to the millivolt input as shown opposite. The cold junction compensation is performed by the integral sensor at the rear of the unit or by a programmable cold junction value. For best accuracy, it is important that the rear plate is fitted to prevent draughts causing temperature differences between the cold...
  • Page 16 INSTALLATION 3.3.5 TRANSDUCER BRIDGE INPUT A transducer bridge requires two sets of connections. A power supply and bridge output. The bridge output is treated as a millivolts signal and connected between pins 4 and 5 as in the diagram below. Note that the power supply could be from the units bridge excitation output option or an external power supply.
  • Page 17 INSTALLATION 3.4 WIRING THE OUTPUT OPTIONS This section applies to optional outputs fitted to the instrument. There are four types of output option available; Change-Over Relay, Dual Relay, Current Retransmission and Programmable voltage Output. These options may be fitted to either slot in any combination.
  • Page 18 INSTALLATION The contact states both these types of relays are summarised in the table below. If the current to be switched is very low (<100mA) the varistors on the relay board may need to be removed. Page 18 RELAY OUTPUT...
  • Page 19 INSTALLATION 3.4.2 Current Output (Retransmission), option 03 The Current output board can support current loops generated from an external power supply, or generate a loop source from the instrument itself. Both of these cases are shown in the diagrams below. Note that connecting directly across pins 1&...
  • Page 20 INSTALLATION 3.4.3 Voltage Output ( Bridge Excitation ),option There are two options. Either a programmable 2 to 20 volt output or a fixed 24 volt output. The connections for both cases are shown below. Page 20 VOLTAGE OUTPUT...
  • Page 21 INSTALLATION 3.5 COMMS BOARD This section explains how the instrument may be connected to a Host computer, either individually or as part of a multidrop network. Although a Personal Computer is shown as the host device, any computer capable of generating RS485 may be used. The electrical communications standard, RS485 is used instead of the commonly available RS232 as its robustness is more suitable for process instrumentation.
  • Page 22 INSTALLATION satisfactorily on some PCs over short distances. This is not a recommended arrangement, but if required for evaluation, should be wired as follows. SMART INDICATOR CARD LINK TX-B Amplicon Liveline TX-A Model RX-A' 485F25 RX-B' +5 TO +13V DC 3.5.1 BASIC CONNECTIONS The diagram below shows the basic connections between the instrument and a Host PC.
  • Page 23 INSTALLATION As only one instrument can transmit at a time. It is possible to connect all of the transmit lines together, this does depend upon each unit being given a unique 'address' or device number, a subject which is dealt with in the programming section of this manual.
  • Page 24 INSTALLATION There is more to the termination at the Host PC receiver. The additional resistors ensure that when all units are tri-state, the differential line rest in an 'idle' state and therefore do not risk detection of spurious data due to noise or slight offsets in the differential inputs.

  • Page 25: User Guide

    USER GUIDE Page 25...

  • Page 26: Programming

    PROGRAMMING 4.0 PROGRAMMING THE INSTRUMENT The unit is a microprocessor based instrument which enables it to satisfy a wide variety of applications through re-programming. The diagram below shows schematically, the operation of the instrument. The programming of the instrument is central to its operation, effecting the way the inputs are processed, how the outputs are handled and what is displayed.
  • Page 27 PROGRAMMING 4.1 PROGRAMMING TUTORIAL GUIDE Before starting with the Tutorial, it is useful to understand that the unit has three operating modes. These are :- DISPLAY PROCESS VARIABLE MODE MENU MODE EDIT MODE THE DISPLAY PROCESS VARIABLE MODE is the principal mode of operation.
  • Page 28 PROGRAMMING 4.1.1 KEY DEFINITIONS All programming is done using the three front panel keys. How these keys are used to program the instrument is shown in this tutorial. The functions of the keys are summarised as follows. The black symbols indicate the keys to press. Shaded keys indicate that the keys should pressed simultaneously.
  • Page 29 PROGRAMMING 4.1.2.1 MOVING AROUND THE MENU We can browse through the other items in the Root menu by pressing Subsequent presses of Cycle moves the menu position from right to left on the previous diagram of the root menu. Notice that after reaching CALIB, the menu position wraps around to the start.
  • Page 30 PROGRAMMING SENSor will now be displayed; we are now in the Input submenu. The diagram below shows our position in relation to other items in the menu. As before, pressing the CYCLE moves the menu position from left to right, wrapping around at the end.
  • Page 31 PROGRAMMING 4.1.3 EDITING A PARAMETER Although the items displayed in the menu can either be submenus or parameters, most of the items in the Inputs menu are parameters. This means that they can be edited. Press the CYCLE key until SENSor is displayed, and then press SHIFT.
  • Page 32 PROGRAMMING To select an option, the ENTER key sequence is used. Now press ENTER. The display will be seen to stop flashing momentarily before returning to Menu mode. Instead of returning back to the SENSor entry, rANgE will now be displayed. The system has automatically stepped on to the next entry to speed the process of programming.
  • Page 33 PROGRAMMING The edit cursor moves one digit to the right. If the SHIFT key is repeatedly pressed, the edit cursor will be seen to wrap around to the most significant digit once more. Therefore it can be seen how a number may be programmed in this field by selective use of the INC and SHIFT keys.
  • Page 34 PROGRAMMING 4.2 THE MENUS The previous section explained how to get into program mode, to move around the menus and how to edit. This section details the contents of the menus and explains how to program the unit for your own particular application. As described before, Program mode is entered by pressing ENTER then CYCLE from the process variable display.
  • Page 35 PROGRAMMING 4.2.1 The SEtP (SETPOINTS) submenu This submenu is provided as a quick means of modifying setpoints. Only the setpoint values are available to be changed. The availability of the setpoints depends upon the output options fitted. The logic directing this is discussed in detail in section 4.2.3, under the Output submenu section.
  • Page 36 PROGRAMMING 4.2.2 The INPUt submenu This submenu is used to program all the characteristics of the input sensor and any signal conditioning that may be required. The selection of an option in the list may effect items further down. Therefore, during programming, the user should start at the top of the menu and work down, to avoid setting an option which may later become obsolete.
  • Page 37 PROGRAMMING 4.2.2.1 SENSOr ( Type of sensor connected ) This parameter defines the type of electrical sensor connected. There are four options. currnt ( Current inputs, internally generated loop ) ( Thermocouple input ) VoltS ( Voltage input, including millivolts ) ( Resistance thermometer ) default setting: currnt 4.2.2.2 rANgE ( electrical range for voltage or...
  • Page 38 PROGRAMMING 4.2.2.3 SENSOr ( Type of thermocouple ) This menu option is only available if a thermocouple has been selected as sensor type. This option allows the user to set the thermocouple type. The options are:- ( K type thermocouple ) ( J type thermocouple ) ( T type thermocouple ) ( R type thermocouple )
  • Page 39 PROGRAMMING 4.2.2.5. rES ( Engineering units display resolu- tion ) This option defines the number of decimal places displayed for the process variable. There are four options: 8888 No places of decimal ( integer value ) 888.8 One place of decimal 88.88 Two places of decimal 8.888...
  • Page 40 PROGRAMMING Default setting: 0.0 4.2.2.8 LO and HI ( Rate Engineering range ) LO and HI are used to define the engineering range for Rate. This range applies to low and high electrical inputs being monitored by the unit. For example, if the electrical input has been set to Volts, on the 100mV range, and it is required that the Rate value be 0.0 at 0mV input and read 50.0 at 100mV, LO and HI are set to the following values:...
  • Page 41 PROGRAMMING Note that the maximum value that may be entered is 64000. default setting: LO: 0.0; HI: 100.0 4.2.2.9 brnout ( Temperature Sensor burnout ) Burnout enables the user to select up-scale (Hi) or down-scale (Lo) burnout condition. This is available for thermocouple or RTD sensors only, and effects the operation of all alarms and output options.
  • Page 42 PROGRAMMING 4.2.2.10 FiltEr ( Input filtering or smoothing ) If an input is particularly noisy, it is possible to filter out noise using this programmable feature. There are eight filter values which may be selected. These filter factors represent the time it would take a step change in an input value to reach approximately 63% of its final value.
  • Page 43 PROGRAMMING 32 SEC ( Filter Factor 32 seconds ) default setting: 2 SEC Also see jump out in section 4.2.2.11 4.2.2.11 JP out ( Filter jump out ) This sets the change in input value, expressed as a percentage of full scale, below which the filter operates and above which the filter is inoperable.
  • Page 44 PROGRAMMING 10 PEr ( Jump out band, 10% of engineering range ) Note that 1% of engineering range for thermocouples is 20 degrees and for RTDs is 10 degrees. default setting: 1 PEr 4.2.2.12 Cond ( Input conditioning for Current and Voltage ranges) This feature is available for Voltage and Current inputs only, and enables the user to specify one of the following input characteristics.
  • Page 45 PROGRAMMING root 52 ( Power 5/2. See 4.2.2.15 ) default setting: LinEAr 4.2.2.13 User linearisation Selection of this option for Cond allows access to the User submenu. Within this menu, thirteen points may be programmed to relate electrical input to engineering value.
  • Page 46 PROGRAMMING Any electrical input falling outside the bounds specified by the table will be regarded as out of bounds and under-range or over-range will be indicated instead of the Process Variable. If a small amount of valid signal over/under range is required, this must be built into the linearisation table. 4.2.2.14 Square Root.
  • Page 47 PROGRAMMING 4.2.2.15 Power 3/2, 5/2 law The root 3/2 and root 5/2 characteristics are for specific applications. For example, calculation of Flow Rate from rectangular and ‘V’ notch weirs require these non-linear corrections. The operation of the characteristic is the same as for square root except that the bottom 1% is not made linear, the response is as follows.
  • Page 48 PROGRAMMING 4.2.3 OUTPUT SUBMENU There are two types of outputs, namely digital (relays) or analogue, which are available as options. Each of the two output slots can contain either of these options. The processor identifies which options are present on power-up and invokes the appropriate programming menus accordingly.
  • Page 49 PROGRAMMING 4.2.3.1 Relay alarms and LED alarms submenus The submenus for the Relay and LED alarms are shown below. Note that the only difference in content between them, is there is no SENSE option in the LED submenu. This is because the SENSE option relates to the activation of a Page 49 OUTPUT MENU...
  • Page 50 PROGRAMMING relay and is therefore irrelevant if no relay is fitted. Both types of alarms activate a discrete LED on the front panel of the instrument if triggered, although this is all a LED alarm does, hence its name. 4.2.3.1.1 ActIOn ( Alarm action ) This programs how the alarm is to operate.
  • Page 51 PROGRAMMING means of adjusting setpoints whilst running. Default setting: 0.0 4.2.3.1.4 HySt ( Alarm hysteresis or dead band ) This enables the hysteresis or dead-band to be programmed. This is the difference between the points at which the alarm triggers and releases and is expressed as a percentage of engineering range.
  • Page 52 PROGRAMMING default setting: 0.00 4.2.3.1.5 DEv ( Deviation band ) This option will only appear if the alarm action is set for deviation, and it signifies the amount, as a percentage of the engineering range that the input variable may vary before the alarm condition is activated.
  • Page 53 PROGRAMMING Each of these trigger points may be regarded as an upper and lower setpoint, and as such the operation of the hysteresis is as on individual upper and lower setpoints. Note that 1% deviation represents 20 degrees Centegrade for a thermocouple and 10 degrees Centegrade for an RTD.
  • Page 54 PROGRAMMING The options are: noninv ( energise relay on alarm, de-energise normally ) iNv ( energise normally, de-energise relay on alarm ) This function is tied in with the fail safe requirements of the relay and its electrical configuration. The following summarises all options. Default setting: noninv 4.2.3.1.7 dElAy ( Delay before activation of alarm) This option allows a delay time to be programmed ( in seconds ) which must elapse...
  • Page 55 PROGRAMMING 4.2.3.2 curnt1(3) CURRENT OUTPUT (RETRANSMISSION ) BOARD The current retransmission board provides a range of current output options. If fitted, the following menu will be available from the Output menu. 4.2.3.2.1 SPAN ( Output current span ) Span is the current range at which the output board is to operate. The options are: 4-20mA ( Output current will vary from 4 - 20mA ) 0-20mA ( Output current will vary from 0 - 20mA )
  • Page 56 PROGRAMMING Default setting: 4-20 4.2.3.2.2 tyPE ( Type of output operation ) This determines the type of operation. The choices are either fixed programmable output or current retransmission based upon the process variable. The options are: rEtrAN ( Retransmission of the input ) PrESEt ( Constant preset output ) Default setting: rEtrAN 4.2.3.2.3 lo ( low retransmission range )
  • Page 57 PROGRAMMING Page 57 OUTPUT MENU...
  • Page 58 PROGRAMMING 4-20mA 0-20mA 0-10mA 4.2.3.2.5 PrESEt ( Preset output value ) This line is only available if PrESEt has been selected as the tyPE of operation. In this mode the current output will directly relate to the value set within this programmable option.
  • Page 59 PROGRAMMING 4.2.3.3 Vprog1 (3) Bridge Excitation board This menu entry is available when a bridge excitation board is fitted in either slot 1 or 2. This is used to program a fixed voltage output from the following range of options. 2 volts output 2 volts output 2 volts output...
  • Page 60 PROGRAMMING 2 volts output 20 volts output default setting: 2 Volts 4.2.4 SyS ( System parameters submenu ) This submenu allows access to all of the system based parameters such as passwords and communications facilities. The system submenu is as follows: 4.2.4.1 PASS ( Password submenu ) Page 60 SYSTEM MENU...
  • Page 61 PROGRAMMING This provides access to the password submenu. The password facility provides protected access to the submenus within the root menu. The level of password protection works progressively down the menu. This submenu is itself protected with a password. The message ENtEr, PASS will be displayed before displaying the password template.
  • Page 62 PROGRAMMING works. If Autocycle is enabled ( its default state ), the menu steps on to the next menu entry after each menu item action. This is convenient when programming a completely new set of parameters into the unit. After each menu item has been programmed, the next one is stepped on to.
  • Page 63 PROGRAMMING 150 ( 150 baud ) 300 ( 300 baud ) 600 ( 600 baud ) 1200 ( 1200 baud ) 2400 ( 2400 baud ) 4800 ( 4800 baud ) 9600 ( 9600 baud ) Default setting: 9600 4.2.4.3.2 dEviCE ( Network device number ) It is possible to multidrop up to 99 instruments on one network.
  • Page 64 PROGRAMMING Default setting:SLAVE 4.2.5 CALIb ( Calibration submenu ) This submenu, which will always have password protection, provides access to enable the total (or partial) recalibration of the System. Casual access into this submenu is therefore discouraged. Page 64 CALIBRATION MENU...
  • Page 65 PROGRAMMING Do not enter the CALIB submenu unless you know exactly what you are doing. If the calibration settings are disturbed, it may be necessary to return the unit to the factory. The submenu may alter with the fitting of various output options, but is represented as follows: 4.2.5.1 OFFSET ( Input offset adjustment ) This is a numeric value in engineering units which is added to the Process Variable...
  • Page 66 PROGRAMMING If the Current Output Board is to be fitted in the unit by the user, it is necessary to use this entry to calibrate the option. Connect up the Current output board to the Sensor input board as shown below. Press ENTER, to commence automatic calibration.
  • Page 67 PROGRAMMING If the Voltage Output Board ( Bridge Excitation ) is to be fitted in the unit by the user, it is necessary to use this entry to calibrate the option. Connect up the Voltage output board to the Sensor input board as shown below. Press ENTER, to commence automatic calibration.

  • Page 68: Operation

    OPERATION 5.0 OPERATION Previous sections have shown how the unit may be configured for user applications. This section shows how the user may access additional information from the Display PV mode and an explanation of how the instrument processes input data and activates outputs.
  • Page 69 OPERATION 5.1.1 VIEW SETPOINTS The function of this mode is to provide a quick read-only access to the Alarm setpoints. This operation is easier to do than to describe and is therefore shown diagramatically below. Pressing the CYCLE puts into VIEW SETPOINTS MODE.
  • Page 70 OPERATION 5.1.2 VIEW PEAK VALUE The maximum Process Variable value measured since switch-on or last reset of Peak/Valley (See 5.1.4), is continuously calculated within the instrument. The current value may be inspected by pressing the SHIFT key whilst in Display PV mode. The display will briefly show PEAc before revealing the actual peak value.
  • Page 71 OPERATION 5.2 INSTRUMENT OPERATION This section describes how the instrument processes input data and activates outputs. The diagram below shows the sequence of processing. 5.2.1 INPUT PROCESSING The electrical input is read in and converted to a digital value, corrections are made for offset and drift.
  • Page 72 OPERATION 5.2.4 ERROR DETECTION The instrument and the input is checked for a range of faults. 5.2.4.1 OPEN CIRCUIT This is only checked for temperature sensors. If an open circuit is detected, the process variable is forced full positive range or full negative range depending upon the brnout setting in the Inputs menu.
  • Page 73 OPERATION 5.7 INSTRUMENT FAULTS The instrument continuously checks itself for correct operation. Detection of a fault causes an error message to be displayed. The error messages are as follows : Err 01 Non Volotile memory failure Err 02 RAM decode error Err 03 RAM size unrecognised Err 04 Input card error Err 05 EPROM checksum error...
  • Page 74 APPENDICES APPENDIX A FITTING OF LEGEND/IDENTIFICATION A standard sheet of legends is supplied which may be used for the engineering units being displayed. The selected legend should be carefully cut from the overall sheet, marked with any appropriate plant tag or identification, and pushed gently into the slot provided in the bottom right hand corner of the front panel of the instrument (see drawing below).
  • Page 75 APPENDICES APPENDIX B TECHNICAL SPECIFICATION INPUT PERFORMANCE @20°C (vii) (vi) Type Nominal range Resolution Accuracy TC K -270 to 1200°C 0.1°C 1°C TC J -210 to 760°C 0.1°C 1°C TC T -270 to 400°C 0.1°C 1°C TC R to 1750°C 0.5°C 2°C TC S...
  • Page 76 APPENDICES ADDITIONAL INPUT SPECIFICATION (iv) Input Average Input impedance Thermal drift Type Acquisition Rate (RTD current) per ºC (ix) 6.8Hz 1M ohm 0.001% (ix) 8.9Hz 1M ohm 0.001%, 0.004% (xi) Volts 8.9Hz 2M ohm 0.002%, 0.011% Current 8.9Hz 51 ohm 0.001% Pt 100 1.7Hz...
  • Page 77 APPENDICES CURRENT RETRANSMISSION BOARD (SOURCE AND SINK) OPTION PERFORMANCE @20°C Accuracy: 20uA (0.1% of Max current) Resolution: (0.01% of the input range ) Response: 100ms for approx 63% of step change Minimum Current O/P: Maximum Current O/P: 21mA (approx) Thermal Drift: 900nA/ºC (0.0045% of Max current /ºC Maximum loop impedance: 1000 ohms...
  • Page 78 APPENDICES RS485 COMMUNICATION OPTION GENERAL Configuration Four wire, Half Duplex (viii) Maximum fan-out 32 units Baud Rate 9600 Data bits Start bits Stop bits Parity none Maximum line length Protocol based on ANSI X3.28 TRANSMITTER Maximum differential output voltage Output voltage with 50ohm load >1.5v RECEIVER Differential input threshold voltage...
  • Page 79 APPENDICES PHYSICAL Dimensions 48 x 96 x 140mm Mounting Panel cutout(91 to 92)mm x (43 to 44)mm Terminals All two part captive screw terminals Weight 850g The accuracy values represent +/- spread from nominal. Unless otherwise stated '%' represents the percentage of full scale value. (ii) '%' represents percentage of reading in stated units (iii)
  • Page 80 APPENDICES APPENDIX C TROUBLESHOOTING 1) UNIT IS COMPLETELY DEAD 1.1) Check supply voltage is present on the rear connector 1.2) Check that supply voltage corresponds with voltage stated on the top of the instrument 1.3) Consult service manual for instructions on replacing internal fuse 2) INCORRECT READING 2.1) Check that the unit is set up for the correct sensor type 2.2) Check that the Engineering range has been set correct for voltage...
  • Page 81 APPENDICES 4) ERROR CODES Several error codes may appear due to the internal self checking of the instrument. These indicate serious faults which cannot be rectified by the user. In the event of these codes being displayed, the unit should be returned to the supplier. The Error Codes are as follows: Err 01 Non Volatile memory failure...
  • Page 82 APPENDICES APPENDIX D MAINTENANCE The instrument is a precision piece of electronic measuring equipment, and yet, due to the nature of its design, requires very little maintenance. 1) CLEANING The only cleaning required is to wipe the front panel with a damp cloth containing a small quantity of detergent.
  • Page 83 APPENDICES APPENDIX E USER COMMUNICATION SOFTWARE This section aims to provide sufficient information to enable a user to write software for a Personal Computer to interface directly with instruments on a network. As all configuration and runtime data are available via the comms, there is great potential to tailor a system to a users individual requirements.
  • Page 84 APPENDICES The other problem obvious from the above schematic is that even though the MASTER transmits to all of the SLAVES simultaneously, only one may respond, otherwise signals will clash together. This is arranged by allocating each SLAVE unit a unique address.
  • Page 85 APPENDICES EXAMPLE 1 DATA REQUEST The MASTER requests the Process Variable from SLAVE device 2. The process is initiated by the MASTER sending the following message. 02<STX>?CH000<ETX><BCC> In order to see what actual data is sent from the host, see the table below. Note that the data is in hexadecimal.
  • Page 86 APPENDICES EXAMPLE 2 DATA IMPOSITION For a second example, take the case of the MASTER issuing a message, this time to change an Alarm Setpoint value again directed at device 2. The MASTER sends the following sequence. The receipt of the message by device number 2 is exactly as in the previous example. This time, however, the ! indicates the message is a data imposition and applies to the Alarm Setpoint (AS).
  • Page 87 APPENDICES Although, at the start of this section, it was stated that there are two types of message; a Data Request and a Data Imposition; there is strictly a third type. This message has the same format as a data imposition except no data is transferred and it has the effect of making the instrument do an action.
  • Page 88 APPENDICES Up to now the control codes have broadly been ignored, although the function of most of them is probably self-evident from the above examples. These will be explained in more detail here. The control codes have two functions. First of all, they provide markers to indicate the start of the message and separate the different types of data with the message.
  • Page 89 APPENDICES The following basic program provides an example of a simple communications interface to run on a PC. The program is coded to use COM1 and communicate with device 1, but these may be modified as required. 10 OPEN ``COM1:9600,N,8,1'' AS #1: header$=''01'' 20 INPUT ``Enter text string ( 0 to quit)'';text$:if text$=''0'' goto 90 50 gosub 100: PRINT#1,TX$ 70 gosub 200: if left$(text$,1) = `'!'' then mid$(text$,1,1)= `'?'':goto 50...
  • Page 90 APPENDICES INSTRUMENT COMMS MNEMONICS DESCRIPTION MNEM INDEX DATA FORMAT PROCESS VARIABLE IN ENGINEERING UNITS VALUE 1ENGINEERING UNITS NO OF DECIMAL PLACES FOR ENG UNITS OPTAIN 0,1,2,3 SENSOR INPUT TYPE OPTION VOLTS,RTD,CURRENT,T/C VOLTAGE RANGE OPTION 100mV,1V,1-5V,10V CURRENT RANGE OPTION 4-20,0-20,0-10mA THERMOCOUPLE TYPE OPTION K,J,T,R,S,E,F,N,B TEMPERATURE SENSOR BURN OUT...
  • Page 91 APPENDICES DATA FORMAT DEFINITION NO DATA No data actually transferred. This type of message initiates an activity within the instrument rather than accessing data. For instance, sending the Text string !ds will cause the unit to store its scratch parameter data area to EEPROM. This must always be done after configuration parameters have been modified via the Comms.
  • Page 92 APPENDICES STRING This is an individually formatted string, usually (but not always ) read-only. See below for details. SY: System request This reports upon the identity of the instrument. This may only be data requested the returned data format is as follows. aabbbbbb0ccde0000ff0000 device type DM for Digital Meter bbbbbb:...

  • Page 93: Index

    INDEX Accuracy Display information Alarms Submenu Editing a parameter alarm state Error codes latch enable setpoint Instrument faults hysteresis Filtering deviation band description relay state input filtering delay jump out Burnout Comms board grounding problems Calbration submenu Input wiring input offset adjustment sensor connection input calibration voltage input...
  • Page 94 INDEX Legend sheet Relay boards wiring Maintence submenu Mechanical installation alarm state Menus latch enable setpoints setpoint input hysteresis output deviation band system invert activation of relay calibration delay Reset all parameters to default Output card Sensor connections wiring Setpoints relay board setpoints submenu current board...

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