Î Î GE Fanuc Automation Programmable Control Products Series 90 Hot Standby CPU Redundancy User’s Guide GFK -0827 December 1993...
Features may be described herein which are not present in all hardware and software systems. GE Fanuc Automation assumes no obligation of notice to holders of this document with respect to changes subsequently made.
Preface This manual is a reference to the hardware components, configuration and operation of the Hot Standby CPU Redundancy system for the Series 90 -70 Programmable Logic Controller. This redundancy system is one of several redundancy alternatives that may be incorporated into a Series 90-70 Programmable Logic Controller system (see Appendix A).
Genius I/O devices to a Series 90-70 PLC. We Welcome Your Comments and Suggestions At GE Fanuc automation, we strive to produce quality technical documentation. After you have used this manual, please take a few moments to complete and return the Reader ’s Comment Card located on the next page.
Contents Chapter 1 Introduction ..........Hot Standby CPU Redundancy Product .
Contents Chapter 2 System Components ........Redundancy CPU .
Contents Chapter 3 Configuration ..........Configuring a Hot Standby CPU Redundancy System .
Contents Chapter 4 Operation ..........Section 1: System Operation .
Contents Section 2: Fault Detection and Control Actions ....Fault Detection ........... Fault Categories .
Contents Figure 1. Example of a Local I/O Configuration with Expansion Racks in a Hot Standby CPU Redundancy System ........Figure 2.
Contents Table 1. Capacities for Redundancy CPU, IC697CPU780 ........Table 2.
restart lowapp ARestart oddapp: ARestarts for autonumbers that do not restart in each chapter. figure bi level 1, reset table_big level 1, reset chap_big level 1, reset1 Lowapp Alwbox restart evenap:A1app_big level 1, resetA figure_ap level 1, reset table_ap level 1, reset figure level 1, reset Figure 1. table level 1, reset Table 1. these restarts oddbox reset: 1evenbox reset: 1must be in the header frame of chapter 1.
contains all redundant Genius Bus Controllers at Serial Bus Address 31; the Secondary PLC contains all redundant Genius Bus Controllers at Serial Bus Address 30. The CPU that currently controls the system is called the active unit, the other CPU is the standby unit.
Features of the Hot Standby CPU Redundancy Product Bumpless switching Synchronized CPUs 20 millisecond scan extension (nominal). This figure is variable, depending on amount of data transferred. One scan switching (in most cases) Configurable backup data size No single point of failure (excluding Genius I/O) Redundant backup communications On–line repair of failed component On–line programming...
I/O Systems for Hot Standby CPU Redundancy Systems Both Series 90-70 Local I/O and Genius I/O systems can be present in a Hot Standby CPU Redundancy control system. The two units are not required to have matching I/O systems. They may have different numbers of I/O racks, and different local I/O or option modules.
a47000 PRIMARY UNIT SECONDARY UNIT RACK 0 RACK 0 TERMINATED I/O CABLE REMOTE DROP LOCAL I/0 CAN BE IN RACKS 0 - 6 RACK 1 RACK 6 I/O CABLE WITH BUILT-IN TERMINATION IC697CBL811 (10 FEET (3m)) IC697CBL826 (25 FEET (7.5m) TERMINATED I/O CABLE Figure 1.
for three consecutive Genius I/O bus scans, the outputs are then controlled by the Genius Bus Controller at serial bus address 30 (Genius Bus Controller in the Secondary PLC). If output data is not available from either bus address 31 or 30, the outputs go to their configured default (OFF or hold last state).
Redundancy CPU Module The same model of CPU must be installed in both the Primary and Secondary PLCs. This CPU, which is the only CPU that currently supports synchronized Hot Standby CPU redundancy, is the CPU 780 (catalog number IC697CPU780). This CPU is similar to the existing IC697CPU782 CPU in that it has an 80386DX microprocessor which operates at a speed of 16 MHz, supports floating point calculations, and requires an expansion memory board which can be 128 KBytes, 256 Kbytes with 256 KBytes of non-volatile...
the two CPUs and provides the communications path for the transfer of I/O data between the two units. An RCM must be configured in both the Primary PLC and the Secondary PLC. The RCM must reside in the CPU rack (rack 0) in a system and there can be no empty slot between the RCM and the CPU (there can be other modules).
If the switch occurs due to a controlled condition such as toggling the unit selection switch on the Redundancy Communications Module or forcing a switch in the user logic program with a SVC_REQ, or because of a fault detected by the PLC CPU, then the switch-over will occur at the beginning of the next sweep.
Programming Considerations There are several features in the operation of the Redundancy CPU which are not supported or are different then operation of other CPUs. These features are listed below and are described in detail in Chapter 4, ”System Operation”. The following features are not available with the Redundancy CPU (CPU 780): I/O Interrupts Timed Interrupts...
The Primary Unit and the Secondary Unit must be configured separately. That is, the programming device should be connected directly to either the Primary or the Secondary Unit to configure that unit. When you have completed configuring that unit, disconnect the programmer from the configured unit and move it to the other unit and proceed with configuration of the second unit.
Commonly Used Acronyms A list of acronyms used in this manual are defined for your convenience in the following table. Acronym Definition Bus Receiver Module Bus Switching Module Bus Transmitter Module Central Processor Unit EPROM Erasable Programmable Read Only Memory Genius Bus Controller Genius Hot Standby Redundancy Genius Modular Redundancy...
Chapter System Components section level 1 1 figure bi level 1 table_big level 1 This chapter describes the hardware components for a Hot Standby CPU Redundancy system. It describes the modules required for the system and provides catalog numbers of the components. For detailed installation instructions for the Series 90-70 PLC, refer to GFK-0262, the Series 90-70 Programmable Controller Installation Manual.
The microprocessor provides all fundamental sweep and operation control, plus execution of non-boolean functions. Boolean functions are handled by a dedicated, VLSI, Boolean Coprocessor (BCP) designed by GE Fanuc. Program and data memory on the CPU 780 is available by the attachment of an...
timer is 10 milliseconds to 1000 milliseconds. The default value for the watchdog timer is 200 milliseconds. The watchdog timer resets at the beginning of each sweep. The fail wait time is included in the watchdog check. The watchdog timer should be set to allow for the expected scan plus two fail wait times.
CPU Mode Switch A three-position toggle switch is mounted near the top of the CPU board. This switch selects one of three operating modes for the CPU: RUN/ENABLED, RUN/DISABLED, or STOP . Although the mode of operation for the CPU can be controlled from both the switch and the programmer, the switch position restricts the ability of the programmer to put the CPU into certain modes.
Memor y Protect Keyswitch The Memory Protect keyswitch is located at the top of the module and has two positions: ON and OFF. This keyswitch is used to manually lock program and configuration data. When the key is in the ”protected” (ON) position, program and configuration data can only be changed by a programmer connected for parallel communications with the CPU 780 (that is, to the Bus Transmitter Module).
Serial Port Connector The 15-pin D-connector at the bottom of the module provides the connection to an RS-422/RS-485 serial port. Its port provides a serial connection to the Work Station Interface (WSI) board installed in the programming computer. For applications requiring RS-232 communications, an RS-232 to RS-422 converter (IC690ACC900) or RS-232 to RS422 miniconverter (IC690ACC901) is available.
Redundancy Communications Module The Redundancy Communications Module (RCM), catalog number IC697RCM711, provides a communications path for sharing data between the two CPUs in the redundant system. In a synchronized system, I/ O data is controlled by one unit (the active unit) but is shared between both units (active and backup units).
a47005 PRIMARY UNIT SECONDARY UNIT ( RACK 0 ) ( RACK 0 ) Redundancy Communications Link Redundancy Communications Link Figure 6. Example of RCM Location in a Hot Standby CPU Redundancy System RCM System Status LEDS A Hot Standby CPU Redundancy system has two RCM modules, each with five LEDs and a momentary pushbutton switch for manually switching between the active and the backup units.
LOCAL SYSTEM ACTIVE Indicates whether the local unit is the controlling (or active) unit in a redundancy system. It is the responsibility of the local unit to set the state of this LED at least once during each sweep; if the local unit is unable to set (or fails to set) the state of the LED, the hardware will force the LED to off after the timer has timed out.
Bus Transmitter Module A Bus Transmitter Module (BTM), catalog number IC697BEM713, is required in both the Primary PLC CPU rack (rack 0) and the Secondary PLC CPU rack (rack 0) in a Hot Standby CPU Redundancy system. The BTM provides a path for Redundancy communications when connected to the Redundancy Communications Module (RCM).
BTM Connectors There are two connectors on the front of the BTM board. The top one provides a parallel connection to a Work Station Interface (WSI) board installed in the programmer for the Series 90-70 PLC. Serial connection to Workmaster II is through a programmer cable (IC647CBL703) 10 feet (3 meters) in length (parallel connection to Workmaster is through a parallel I/ O cable, IC600WD005A).
I/O Bus Signal Termination The I/O bus signals must be terminated at the end of the bus. In a standard PLC system this is done by installing a resistor pack, located inside of a terminator plug (catalog number IC697ACC702) on the bottom connector of the BRM module that is installed in the last I/O expansion rack in the system.
The Hot Standby CPU Redundancy system uses a single Genius bus and requires one GBC module in the Primary PLC and one in the Secondary PLC; however there can be multiple Genius busses configured in this manner in a system. The GBCs in the Primary PLC are assigned SBA 31, and the GBCs in the Secondary PLC are assigned SBA 30.
CH 1 OK The CH 1 OK LED is the middle LED. It operates identical to the Module OK LED in that it is ON after the board has successfully completed the power-up diagnostics and OFF if a failure has been detected during the power-up diagnostics, or if its bus or bus controller fails while the CPU is running (even in the STOP mode).
Chapter Configuration section level 1 1 figure bi level 1 table_big level 1 This chapter describes how to configure a Series 90-70 PLC system for Hot Standby CPU Redundancy. Several parameters in addition to the normally configured CPU parameters must be configured for the Redundancy CPU 780. A description of all of the parameters for a redundancy system is provided first, followed by an example of a Primary system configuration and a Secondary system configuration.
Redundancy System Requirements For a redundant CPU configuration using the Hot-Standby Redundancy scheme to be valid, the following requirements must be true in both the Primary Unit and the Secondary Unit in the redundancy system. One configuration must be set to Primary; the other to Secondary. The control strategy configurable parameter must be set to ”GHS”.
Screens for Fault Category Configuration A new Fault Category Configuration screen is displayed for the CPU 780. This new screen has two columns of fault actions for the configurable fault groups/categories. The following sample screens show the Fault Category Configuration screens as they appear in Logicmaster 90-70.
The Fault Type is shown at the left. The first column under Fault Category (CFG) shows which faults are FATAL and which faults are DIAGNOSTIC for this CPU, when it is the only running CPU (i.e., stand-alone with no backup available). This column can be edited for each fault group/category to select FATAL or DIAGNOSTIC so that a safe shutdown or fault tolerant operation can be selected for when a failure occurs with no backup ready.
cable connecting the PLC to the programmer should only be plugged and unplugged when the programmer is powered up and offline. Avoid powering the parallel programmer up or down while connected to a running PLC. Configuration of a Redundancy CPU Module The redundancy CPU module, IC697CPU 780 must be configured as a rack module in rack 0, slot 1.
The detail screen of the currently configured CPU module is displayed. The following screen shows the CPU module detail screen for the currently displayed module. To select the CPU 780 Redundancy CPU module, press the cpu softkey (F1). A list of the available CPU modules is displayed with the currently selected CPU module highlighted in reverse video.
If the existing configuration does not require any modification to suit the redundant CPU configuration, the prompt ”REPLACE displayed module ? (Y/N)” will be displayed beneath the softkey strip instead of the message box. If you answer ”Y”, page 1 of the detail screen for the redundant CPU (IC697CPU 780) is displayed, If you were to answer ”N”, the previous CPU is displayed.
3. In a redundant CPU system, RCMs cannot be configured in expansion racks. 4. Rack 7 cannot be seen nor edited. Redund Type This parameter specifies whether the CPU is configured as the primary controller or the secondary controller. The Redund Type has three possible choices: PRIMARY, SECNDARY, or SIMPLEX.
Constant Window Sweep Mode To change the Sweep Mode, move the cursor to the Sweep Mode field and press the Tab key until the desired mode is displayed. Below is the detail screen (page 2) of a redundant CPU configured for CNST WND (constant window) sweep mode. When a Series 90-70 redundant CPU is configured for CNST WND (constant window) mode, the window value will automatically be set to 10 msec.
set for SIMPLEX mode. The parameters on this screen are Ctrl Strgy (Control Strategy), Fail Wait and SHARED I/O. Ctrl Strgy This parameter specifies which type of control strategy is selected for a redundancy system. The valid entry is three ASCII characters (A...Z). The only value that is supported at this time is Genius Hot Standby (GHS).
Table 4. Shared I/O Data Parameters I/O Parameter Description and Valid Entries %I Ref Adr Starting address for redundant %I data region. Range is %I00001...%I12288. The starting address is bit aligned. Default value is %I00001. %I LENGTH The bit length of the redundant %I data region. Range is 0...12288. Default value is 0. %Q Ref Adr Starting address for redundant %Q data region.
Note that the memory for the Shared I/O data that is stored at configuration must be subtracted from the amount of memory on the configured expansion memory module. The calculation for the size of the memory for Shared I/O data is (bytes of Input data transfer plus bytes of Output data transfer plus 8 Kbytes for synchronization information).
Configuring a CPU Expansion Memory Board To configure a CPU expansion memory board for the CPU 780, press the expbd softkey (F9) and then the memory softkey (F1). Position the cursor on the desired expansion memory board and press Enter to select that board. The detail screen for the expansion memory board and the displayed catalog list for the available CPU expansion memory boards is shown below.
Configuration of a Redundancy Communications Module As described previously, one Redundancy Communications Module (the Local unit) must be configured in rack 0 (can be in slots 2 to 9). There must not be an empty slot between the CPU 780 module and the RCM module. If there is an empty slot, the configuration will be invalid.
To display the RCM catalog list, press the rcm softkey (F3). The RCM catalog list is then displayed as shown below. Next, press the Enter key, the following screen is displayed to confirm that you have selected the RCM catalog entry. You have just configured the Local RCM in rack 0.
Configuration of a Genius Bus Controller For this example, assume that a Genius Bus Controller has been configured in slot 3 of rack 0. In a Hot Standby CPU Redundancy system, the Redundancy parameter (Redund Mode) of a Genius Bus Controller can only be NONE or RED CTRL; any other value is not valid.
Serial Bus Address All redundant GBCs in the Primary CPU redundant system MUST be configured at SBA 31. In the sample screen on the previous page, the rack level GBC is configured at SBA 31. The Bus level GBC is automatically configured at SBA 30. All redundant GBCs in the Secondary CPU redundant system MUST be configured at SBA 30.
Configuring a Primary Redundant PLC The steps required for configuring a Primary Redundant PLC are described below. The Primary PLC and the Secondary PLC must be configured separately. An example of the configuration screens for each system is provided on the following pages. The programmer must be connected to the CPU in the Primary PLC to configure the Primary PLC and then moved to the CPU in the Secondary PLC to configure the Secondary PLC.
Select the Redundancy CPU Module Move the cursor to the line for the Redundant CPU, IC697CPU 780, and press the Enter key. A message is displayed beneath the softkey selection strip: ”REPLACE displayed module ? (Y/N)”. Press the Y key to replace the currently displayed CPU with the CPU 780.
Press the PgDn key again to go to the next page of the CPU module. The default screen for page 3 of the CPU detail screen appears as shown below: Select an Expansion Memory Board To configure a CPU expansion memory board for the CPU 780, press the expnd softkey (F9), then the memory softkey (f1).
Press the Esc key twice to return to the rack level display, which now appears as shown below. Configure the Redundant Communications Module To configure an RCM in rack 0, slot 2, move the cursor to slot 2 and press the bem softkey (F3).
Configure a Genius Bus Controller To configure a Genius Bus Controller module in rack 0, slot 3, position the cursor on slot 3 and press the genius softkey (F2). To display the catalog list for the Genius Bus Controller, press the gbc softkey (F1). Press the Enter key to select the Genius Bus Controller module.
Press the Esc key to return to the rack level screen. From the rack level screen press the zoom softkey (F10). The following bus level screen is displayed: To view the Genius Bus Controller (block level) at SBA 30, position the cursor on BUS ADR 30 and press the zoom softkey.
At this point, Press the Esc key and the bus screen will appear as shown below. Configure Genius I/O Blocks We will now configure a block for Bus Address 29. Move the cursor to block 29 and configure a bus block (Discrete Input block IC660BBD110 for this example) by selecting the F1 function key (d in), then Enter.
When you have completed configuring Genius blocks, press the Esc key to go from the block level display back to the bus level display. The bus display will now appear as shown below. Configure the Bus Transmitter Module Press the Esc key to return to the rack level display. A message will be displayed reminding you to configure a Bus Transmitter Module for this rack (since it had not been configured earlier).
Configuring a Secondary Redundant PLC This section describes the steps for configuration of a Secondary PLC. The programmer for Logicmaster 90-70 software must be connected to the Secondary PLC in order to configure the Secondary PLC. There are several ways to configure a Secondary PLC in a Hot Standby CPU Redundancy system.
Position the cursor on rack 0, slot 1. Press the zoom softkey (F10) to zoom into the CPU module configured in slot 1. The detail screen (page 1) for the CPU module appears as shown below: Change Redund Type Change the Redund Type: parameter value from PRIMARY to SECNDARY by pressing the Tab key then the Enter key.
Press the Esc key twice to save the changes you have just made. This completes the process of converting a Primary PLC redundancy system configuration to a Secondary PLC redundancy system configuration. The differences between the Primary system and the Secondary system are: 1.
Chapter Operation section level 1 1 figure bi level 1 table_big level 1 This chapter discusses: the normal operation of a Hot Standby CPU Redundancy PLC system; what happens when a fault is detected and the system does not operate normally; how to restore the system to normal operation;...
4. System Configuration verified. 5. System interrogated and initialized. 6. Presence of other CPU detected and RCMs initialized. 7. Complete user program verification. 8. Synchronize with the Redundant CPU. When powering up the unit configured as the Secondary Unit in a Redundant system and no remote unit (the Primary Unit) is detected, the Secondary Unit will wait up to 15 seconds to see if the remote unit will also power up.
Resynchronization of the Redundant CPU Whenever a CPU is attempting to get back in synchronization with the currently active CPU, a resynchronization process will occur. This resynchronization process will occur any time a CPU performs a STOP to RUN mode transition. This process will start by determining which role each CPU is to play.
Hot-Standby Redundancy Control Strategy In the Hot-Standby Redundancy Control Strategy, the primary CPU (designated by all GBCs addressed at bus address 31), is always the preferred CPU. The secondary CPU (designated by all GBCs addressed at bus address 30) will have the outputs enabled to its GBCs at all times whether it is in control or not.
Synchronous Scan The figure below shows the sweep components for the active and the backup CPUs. It shows the two communication points in the sweep. The first communication point is immediately after the inputs are scanned. At this point in the sweep the newly read inputs are sent from the active CPU to the backup CPU and synchronization information is passed.
The transfer of the redundancy data during each sweep will be in blocks with each block checked for data integrity. The transferred data will be held in a temporary area by the backup CPU until all data has been received and verified from the active unit. Then the backup CPU will copy that data from the temporary area to the actual PLC memories.
through %P0008 on the backup unit will not change. %T0002 will be set whenever the operation is successful and the data can be used. |REM_RDY %T00001 |——| |—————————————————————————————————————————————————————————————————————( )— _____ |REM_ACT | %M00001 |——| |———| SVC_|———————————————————————————————————————————————————————————( )— | REQ | | CONST —|FNC | 00027 |%P00001—|PARM |...
If the switch occurs due to a controlled condition such as toggling the RCM unit selection switch, forcing a switch in the user logic program, or because of a fault detected by the PLC CPU, then the switch-over will occur at the beginning of the subsequent sweep. The delay will be up to 1 sweep with the possibility of an input and an output scan after failure detection.
%S References for CPU Redundancy There are seven special %S references which reflect the status of the Redundancy units: %S33 through %S39. The definition of these LEDs is shown in the following table. Table 7. Definition for% S Reference for Redundancy Status %S Bit Definition Nickname...
Redundancy CPU Considerations The Redundancy CPU (CPU 780) has several restrictions and differences in operation as compared to other Series 90-70 CPUs. The following features are not available with the CPU 780: I/O Interrupts Timed Interrupts VME Integrator Racks. Stop I/O Scan mode Flash operation Features not Available with CPU 780 I/O Interrupts...
Differences in Operation for CPU 780 The following features operate differently with the CPU 780 than they do with other Series 90-70 CPUs: RUN/DISABLED mode Configuration of Fault Actions STOP to RUN mode transition Background Window Time (default is different) RUN Disabled Mode RUN/DISABLED mode causes all physical outputs to go to their default state in that PLC.
Following are several examples that illustrate the above guidelines. Each example gives the role of each unit, its current operating mode, and the state of the LEDs on the RCMs. An X indicates that the corresponding LED and %S bit is ON. A.
E. Role switches are allowed on both units. Primary Unit Secondary Unit Backup Active (see NOTE below) RUN/ENABLED RUN/ENABLED X OK X OK X LOC_RDY X LOC_RDY LOC_ACT X LOC_ACT X REM_RDY X REM_RDY X REM_ACT REM_ACT Role switches are not allowed on either unit. Primary Unit Secondary Unit Backup...
Specific fault actions are described in Section 2 of this Chapter. However, you can configure whether or not a stand-alone CPU (after failure of the other CPU) will stop if another fault occurs. You can select the fault actions (either diagnostic or fatal) for when a given CPU is operating without a backup available.
Background User Checksum and Background Window Timing Instructions The following information is provided to allow you to guarantee full coverage of the number of program words verified by the User Program Checksum per sweep and the Background Window Diagnostics within a certain amount of time. It is important to understand that the more checksums performed and the larger the background window, the longer the sweep will take.
Where the Background Window Time is the time in milliseconds that you should set the background window timer. The other elements in the formula are described above in the calculation for words per sweep. The constants (F and C) are for the CPU 780. 448 0 x (100 + 176 x 0.0008 x 2) Background Window Time = (120000 –...
Genius Bus Controller Switching Genius Bus Controllers will stop sending outputs to blocks when no data has been received from the PLC CPU for a period equal to two times the configured watchdog timeout. If the CPU on the active unit becomes inoperative in an uncontrolled fashion (for example, because of a power failure), the Genius Bus Controllers will detect this within twice the watchdog setting, and stop sending outputs to the Genius blocks.
Section 6: Fault Detection and Control Actions This section describes how faults are handled in a Redundancy system. It discusses how faults affect the operation of the Redundancy system, describes categories of faults, describes how faults are detected, describes the actions taken when faults are detected, and discusses on-line repair of individual components.
3. faults and failures that are detected in the background. Faults and failures that are detected immediately are those that are identified within the current sweep. These faults include I/O data corruption, single bit RAM failures, power supply failures, processor failures, VME bus failures, and no response from an addressed module.
PLC Fault Table The following table lists fault zoom Help text and messages for error codes associated with the redundancy fault group. Table 8. Fault Zoom Help Text for Redundancy Error Codes Error Code Message Fault Description Corrective Action Primary Unit is Active and The primary and secondary units have None required.
Faulting RCMs, Losing Links, and Terminating Communications There are distinct differences between losing a redundant communications link, faulting an RCM, and terminating communications. Faulting the RCM module occurs only when a hardware related failure occurs such as a parity error or VME bus error. Action taken when a board is faulted: Module Failed fault is logged in the PLC Fault Table.
In this case, if the RCM is at fault, it will need to be replaced before power is restored. Terminating Communications occurs when the two units get out of synchronization. The action taken when communications is terminated is the same as when a link has timed out, except that actions are taken on both links and the Communications Terminated fault is logged rather than Link Timeout.
Fault Actions in a CPU Redundancy System Fault actions in the Hot Standby CPU Redundancy System are handled differently than those in a non-redundancy (Simplex) system. Whenever there is a ”ready” backup unit configured in the system, the fault actions in the active unit will not be those normally specified by the user.
Table 10. Maskable Fault Group Actions Fault Action Simplex Mode Redundant Mode Fault Group User Configurable LOSS_RACK Non-Fatal Fatal LOSS_IOC Non-Fatal Fatal LOSS_IO_MOD Non-Fatal Non-Fatal LOSS_OTHR_MOD Non-Fatal Non-Fatal ADD_RCK Non-Fatal Non-Fatal ADD_IOC Non-Fatal Non-Fatal ADD_IO_MOD Non-Fatal Non-Fatal ADD_OTHR_MOD Non-Fatal Non-Fatal IOC_FAULT Non-Fatal Conditionally Fatal...
Table 11. Non-Maskable Fault Group Descriptions Table Fault Group Type Description SYS_BUS_FAIL System bus failure. NO_USER_PRG No User ’s Program on Power-up. BAD_USER_RAM Corrupted User RAM detected on Power-up. WIND_CMPL_FAIL Window Completion Failure in Constant Sweep Mode (i.e., all windows failed to receive their allotted time). PASSWD_FAIL Password Access Failure.
On-Line Repair With a Hot Standby CPU Redundancy system most system component failures can be repaired by replacing the failed component while the system is on-line. These on-line repair procedures are possible because of the role switching capability of the units in the system.
Power Supply The power supply has adequate internal fault detection which will cause it to automatically shut down if there is a failure. In an orderly shut down, the power supply will first assert the ACFAIL signal before it asserts the SYSREST signal. This will give the active PLC time to notify the backup PLC that it can no longer control the process.
If an RCM fault is detected, proceed as follows: STOP the unit with the suspected bad RCM. Turn power off at that rack. Unplug the terminated cable from the RCM and replace the module. Reconnect the terminated cable. Power-up the rack (mode switch is still in STOP). Verify that the REMOTE ACTIVE and REMOTE READY LEDs are on, or look at the %S bits in the stopped unit.
Genius Bus Genius bus faults are not fatal to the PLC. However, if a bus fault exists, it exists for both systems. There may be situations where one controller can communicate to more blocks than the other controller can. Since both controllers are running with the same outputs and shared inputs, and both controllers are still synchronized, the blocks will choose which controller to respond to, if either can be heard.
Appendix Redundancy Alternatives section level 1 1 figure_ap level 1 table_ap level 1 Redundancy Alternatives There are several redundancy alternatives for the Series 90-70 Programmable Logic Controller. These redundancy options consist of implementation of the redundancy feature through a user logic program or through a redundancy product which consists of both hardware and software.
a47009 START Fault Tolerant FAILURE TRIPLEX SYSTEM STRATEGY CPUS HOT STANDBY Fail Safe Redundancy (2 CPUS) OPTIONS Option Key (see Table 1) SINGLE 1, 2, 3 OPTIONS REDUNDANT DUPLEX 1, 2 CPUS APPLICATION LOW COST LOGIC DUPLEX CPUS LOWEST COST PRODUCT I/O COUNT 1A-C, 2, 3...
Table 13. Redundancy Options Output Option Scan Data I/O System Selection Redund. Redund. Selection Guide Sync Sync Method 2 90-70s Application 90-70 yes - 2 Higher Density Analog Inputs Logic (I/O Scanner) Standby Hot Standby 2 90-70s Application 90-30 yes - 2 More competitive I/O Logic (GCM+)
Series 90-70 Redundancy Through Application Logic The following restrictions apply using the current Series 90-70 for redundancy applications requiring synchronization (these restrictions do not apply to the Hot Standby CPU Redundancy product). Do not use transitional contacts or coils since this information cannot be transferred across the link.
Index Cable, programmer connection, 23 Acronyms, list of, 12 Cable, programmer connection, connect- Active and backup sweeps, 59 ing and disconnecting, 9 Active unit, 2 , 4 , 7 , 8 , 9 , 16 , 19 , 20 , Cable, terminated, 4 , 5 , 6 , 24 , 28 21 , 25 , 57 , 58 , 59 , 60 , 61 , 65 , 68 Calculations, background user checksum,...
Index Connecting Logicmaster 90, 31 Connector, serial port, 18 Fail wait time, 8 Connectors, battery, 17 Fail wait time configuration, 36 Considerations, programming, 10 Failsafe operation, 2 Considerations, redundancy CPU, 64 Fault action, diagnostic fault action, 72 Constant sweep mode configuration, 35 Fault actions conditionally fatal, 77 Constant window sweep mode configura-...
Index Genius bus, multiple, 26 Logicmaster 90 configuration, require- ments, 28 Genius I/O, bus controller, 24 Logicmaster 90 connection, 31 Genius I/O system, 4 Logicmaster, serial COM port version, 18 Grounding, programmer, 9 Logicmaster, WSI version, 18 Guidelines for run disabled mode, 66 Losing links, 75 Help text, redundancy error codes, 74 Maskable fault group actions, 78...
Index Operation, differences for cpu 780, 65 local system ready, 20 remote system active, 21 Operation of a cpu redundancy system, remote system ready, 21 pushbutton for unit selection, 21 OVR_PRE %S reference, 70 system status LEDs, 7 Redundancy CPU considerations, 64 Redundancy cpu considerations I/O interrupts, 64 timed interrupts, 64...
Index Sweep mode constant, 35 constant window, 35 S (%), references, 7 normal, 34 Scan time, effect of bumpless switching, 8 Sweeps, active and backup, 59 Switch to backup unit time, 8 Scan, synchronous, 59 Switching control to backup unit Screens for fault category, 29 from user program via SVCREQ, 61 Secondary unit, 25...