PLC-5 Troubleshooting Help06/11/2018Troubleshooting the operation of a PLC-5 system can be a tricky proposition. The Allen Bradley PLC-5 processor has four status lights that are used to give users indication if the operational condition of the processor. These are BATT, PROC, FORCE, and COMM.The BATT LED is an indicator of the battery condition. If the LED is off, the battery is good. This is normal operation. If the BATT LED is on with a steady red indication, the battery is low and it is recommended that it be replaced within ten days.The PROC LED is an indicator of the overall processor operation. If the LED is on with a steady green indication, this is normal operation. The processor is in RUN mode and fully operational. If the green LED is blinking, this is also normal operation and processor memory is being transferred to the EEPROM. If the PROC LED is blinking red, this is an indication of a major fault with a probable cause of a run-time error. The recommended action is to check major fault bit in status file, clear the fault bit, correct the problem, and return to RUN mode. If the PROC LED is on steady red, this is also an indication of a major fault with the probable or possible causes that the user RAM has a checksum error, there is a memory module error, or internal diagnostics have failed. The recommended actions for this is first to clear the memory and reload the program. The next recommended action is to Check backplane switch settings and/or insert correct memory module. Next, power down, reseat the processor and power up. Then, clear memory and reload your program. Replace EEPROM with new program. Then, if necessary, have the processor repaired. If the PROC LED is off, the processor is in program load or TEST mode or is not receiving power. The recommended action is to check the power supply and connections to ensure proper power is being supplied. If the PROC LED is alternating red and green, the processor is in FLASH-memory programming mode. The probable cause is a processor FLASH memory checksum error. The FORCE LED is and indicator of SFC or I/O forces. If this LED is on steady amber it is an indication that SFC and/or I/O forces are enabled. If the LED is blinking amber it indicates that SFC and/or I/O forces are present, but not enabled. If the FORCE LED is off, SFC and/or I/O forces are not present.The COMM LED is an indicator of the processor’s communication function. If the COMM LED is blinking green, there is transmission on channel 0. This is normal operation. If this LED is off, there is no transmission on channel 0. This is normal operation if the port is not being used. But if the port is used, then this is an indication of no transmission.If during the course of troubleshooting your PLC-5 you find the processor or any other component of the system in need of more than a reset or minor correction, call on the Allen Bradley PLC experts at PES today at 800-732-4695. Back To Blog
PLC-5 Troubleshooting Help06/11/2018Troubleshooting the operation of a PLC-5 system can be a tricky proposition. The Allen Bradley PLC-5 processor has four status lights that are used to give users indication if the operational condition of the processor. These are BATT, PROC, FORCE, and COMM.The BATT LED is an indicator of the battery condition. If the LED is off, the battery is good. This is normal operation. If the BATT LED is on with a steady red indication, the battery is low and it is recommended that it be replaced within ten days.The PROC LED is an indicator of the overall processor operation. If the LED is on with a steady green indication, this is normal operation. The processor is in RUN mode and fully operational. If the green LED is blinking, this is also normal operation and processor memory is being transferred to the EEPROM. If the PROC LED is blinking red, this is an indication of a major fault with a probable cause of a run-time error. The recommended action is to check major fault bit in status file, clear the fault bit, correct the problem, and return to RUN mode. If the PROC LED is on steady red, this is also an indication of a major fault with the probable or possible causes that the user RAM has a checksum error, there is a memory module error, or internal diagnostics have failed. The recommended actions for this is first to clear the memory and reload the program. The next recommended action is to Check backplane switch settings and/or insert correct memory module. Next, power down, reseat the processor and power up. Then, clear memory and reload your program. Replace EEPROM with new program. Then, if necessary, have the processor repaired. If the PROC LED is off, the processor is in program load or TEST mode or is not receiving power. The recommended action is to check the power supply and connections to ensure proper power is being supplied. If the PROC LED is alternating red and green, the processor is in FLASH-memory programming mode. The probable cause is a processor FLASH memory checksum error. The FORCE LED is and indicator of SFC or I/O forces. If this LED is on steady amber it is an indication that SFC and/or I/O forces are enabled. If the LED is blinking amber it indicates that SFC and/or I/O forces are present, but not enabled. If the FORCE LED is off, SFC and/or I/O forces are not present.The COMM LED is an indicator of the processor’s communication function. If the COMM LED is blinking green, there is transmission on channel 0. This is normal operation. If this LED is off, there is no transmission on channel 0. This is normal operation if the port is not being used. But if the port is used, then this is an indication of no transmission.If during the course of troubleshooting your PLC-5 you find the processor or any other component of the system in need of more than a reset or minor correction, call on the Allen Bradley PLC experts at PES today at 800-732-4695.