OMRON CJ Series PLC Practical Guide

User set I/O table: Create an I/O table through CX Programmer and download it to the CPU. Verify the consistency between the actual unit and the table when powered on. Suitable for systems that require fixed addresses or reserved slots.

Initial word setting: The starting word address can be set for each slot in the I/O table (up to 64 groups). For example, if slot 0 is set to CIO 0000 and slot 3 is set to CIO 0100, the empty slots in the middle or units with different widths will be automatically allocated consecutively.

4.3 File Memory and Simple Backup

The CJ1-H/CJ1M CPU has built-in flash memory and automatically backs up user programs and parameter areas. In addition, the following file operations are supported:

Memory card: Compact Flash card (HMC-EF372/672/183), used for program transfer and data recording.

EM file memory: Convert a portion of the EM area into file memory (set the starting bank through PLC Setup).

Annotation memory (version 3.0+): stores symbol tables, annotations, and program indexes.

Simple backup: One click backup of the settings of the CPU unit and CPU bus unit (such as DeviceNet, serial communication unit) to the storage card. Operation: DIP switch 7 ON, press and hold the memory card power switch for 3 seconds (write) or power on (restore).

Common troubleshooting: from indicator lights to error codes

5.1 Meaning of CPU unit indicator lights

Meaning of indicator light color and status

RUN green light running normally (MONITOR or RUN mode)

ERR/ALM red light fatal error (including FALS)

ERR/ALM red flashing non fatal error (including FAL)

INH orange light output OFF position (A50015) ON, all outputs turned off

PRPHL Orange Flashing Peripheral Port Communication

COMM orange flashing RS-232C port communication in progress

BKUP orange light is backing up to flash memory (power off prohibited)

MCPWR green light storage card power supply is normal

BUSY orange flashing memory card is accessing

5.2 Common Error Codes and Troubleshooting

Fatal error (RUN OFF, ERR/ALM ON)

Possible causes and solutions for error code names

80F1 memory error user program verification error; PLC Setup verification error; I/O table verification error check A403 positioning error area; Resend program or parameters

80C0~80CF I/O bus error, poor connection between units; Terminal cover not connected, check connection; Re plug and unplug the unit; Check the terminal cover

80E9 Unit Number Duplicate CPU Bus Unit or Special I/O Unit Number Duplicate Check A410/A411~A416, Modify Duplicate Unit Number

80E1 I/O points exceed the total I/O points and exceed the CPU capacity; Reduce the number of I/O points or units for a single rack with more than 10 units

80F0 program error without END instruction; Task error; Illegal instruction check A295 error flag, check A298/A299 program address

809F cycle timeout: If the cycle time exceeds the monitoring time, increase the monitoring time or optimize the program

Non fatal error (RUN ON, ERR/ALM flashing)

Possible causes and solutions for error code names

008B Interrupt Task Error: Executing IORF/FIORF in interrupt task conflicts with cyclic refresh, disabling cyclic refresh of this special I/O unit (PLC Setup)

009B PLC Setup Setting Error Parameter Setting Out of Range Check A406 Positioning Error Address

0200~020F CPU bus unit error data exchange error check A417 corresponding unit number, restart the unit or replace it

0300~035F Special I/O Unit Error Unit Internal Fault or Communication Error Check A418~A423 Corresponding Unit Number

00F7 battery low voltage battery voltage drops. Replace the battery or disable battery detection

5.3 Diagram of Troubleshooting Process

Power check:

POWER indicator light not on → Check if the input voltage is within the allowable range (AC: 85-264V, DC: 19.2-28.8V); Check if the terminal screws are loose; Replace the power supply unit.

I/O check (example of output point not functioning):

Is the monitoring output bit (such as CIO 000500) ON? If OFF, check the program logic.

If ON but the output unit indicator light does not light up, check the output unit fuse (some models have a fuse indication); Check the external load power supply; Check the wiring.

If the indicator light is on but the load does not move, check the load itself; Check the COM terminal wiring.

Cycle timeout handling:

Check if A40515 (Peripheral Service Cycle Long Flag) is ON. If ON, change the CPU processing mode from parallel mode to normal mode or peripheral service priority mode.

Check if A440 (maximum interrupt task processing time) is too long and optimize the interrupt program.

Set the minimum fixed cycle time (PLC Setup address 208) to stabilize the I/O response.

Maintenance and battery replacement

6.1 Regular inspection items

Suggest checking every 6 months to 1 year:

Environmental temperature (0~55 ℃), humidity (10%~90% without condensation)

Power supply voltage fluctuation

Is the unit installation loose

Tightening condition of wiring terminal screws

Remaining battery life (CJ1W-PA205C can be displayed through the front panel)

6.2 Battery Replacement

CJ1/CJ1H CPU uses CPM2A-BAT01, CJ1M uses CJ1W-BAT01. The battery life is about 5 years at 25 ℃, and it will shorten with increasing temperature.