OMRON CJ Series PLC Practical Guide

OMRON CJ series PLC system: Engineer's practical manual from unit version management to troubleshooting

In industrial automation sites, OMRON CJ series programmable logic controllers (PLCs) are widely used for control from single machine equipment to complex production lines due to their compact size, high performance, and flexible scalability. However, facing multiple sub series such as CJ1H, CJ1M, CJ1, as well as constantly updated Unit Versions, engineers often encounter challenges in selection, system integration, and maintenance: what are the functional differences between different versions? How to determine which instructions the CPU unit supports based on the unit version? How to quickly locate I/O allocation faults? What are the precautions for battery replacement? This article is based on the official technical information of CJ series PLC, providing engineers with a complete set of engineering practice guidelines from unit version management, system configuration, memory allocation, troubleshooting to daily maintenance.

Unit version: "Invisible ID Card" for CJ series CPUs

The CJ series CPU units have introduced a "unit version" management mechanism to distinguish the set of functions possessed by CPU units produced in different periods. This concept is crucial for determining program compatibility and functional support.

1.1 How to identify unit versions

The unit version is marked on the right side of the batch number on the CPU unit nameplate, in the format of "Ver. □□". For example, the version of CJ1H-CPU67H-R unit may be 4.2, 4.1, or 4.0. For CPU units produced before November 4, 2003, the nameplate does not display the version (referred to as Pre Ver. CPU unit).

1.2 Starting point for versions of different models

CJ1H-CPU □□ H-R (high-speed type): version starting from 4.0

CJ1H-CPU □□ H/CJ1G-CPU □□ H/CJ1M-CPU □□: Version starting from 2.0

CJ1G-CPU □□ P (Loop Control CPU): CPU unit component version 3.0 or higher, LCB component version 2.0

After understanding the starting point of the version, engineers must confirm the compatibility of the new and old units when replacing the CPU or upgrading the system, otherwise it may cause the program to fail to download or run incorrectly.

1.3 Relationship between Unit Version and Function Support

New features in version 4.0 and above (requires CX Programmer 7.0 or higher):

Function block online editing

Input/output variables in functional blocks (supporting large amounts of data transfer)

Text string support in function blocks (ST language programming)

New features in version 3.0 (requires CX Programmer 5.0 or higher):

Function block (compliant with IEC 61131-3 standard)

Serial gateway (converts FINS commands to CompoWay/F)

Annotation memory (storing symbol tables, annotations, etc. in internal flash memory)

Simple backup data extension (supports annotation backup)

Free running timer (A000: 10ms increments, A001: 100ms increments)

New features in version 2.0 (requires CX Programmer 4.0 or higher):

Upload/download of individual tasks

Improved password read protection (can protect individual tasks)

Write protection through network FINS commands

Online network connection without the need for an I/O table

Up to 8 levels of network communication (formerly 3 levels)

Connect PLC online through NS series PT

Slot header setting (up to 64 groups)

Power on automatic transmission without parameter files (REPLACE. OBJ)

Operation start/end time record (A515~A520)

New application instructions: MILH/MILR/MILC, TPO, GRY, PRV2, combination instructions (TKY/HKY/DSW/MTR/7SEG), time comparison instructions, explicit message instructions, extension block comparison BCMP2, etc

Important notice: If a program containing features specific to a higher version is downloaded to a lower version CPU unit, compilation will encounter an error and download will fail. If passed When transferring OBJ files, program errors may occur and the CPU will stop running during startup or execution of related functions.

CPU Unit Selection Guide: How to Choose CJ1H, CJ1M, CJ1

The CJ series is mainly divided into three categories of CPU units, each suitable for different performance requirements.

2.1 CJ1H CPU Unit (High Performance Type)

Model, Program Capacity, Data Memory (DM+EM), Basic Instruction Execution Time, Extended Rack Count

CJ1H-CPU67H-R 250K Step 448K Word 0.016 μ s 3

CJ1H-CPU66H-R 120K steps 256K words 0.016 μ s 3

CJ1H-CPU65H-R 60K steps 128K words 0.016 μ s 3

CJ1H-CPU64H-R 30K steps 64K words 0.016 μ s 3

High speed type (- R) features: basic instruction 0.016 μ s, special instruction 0.048 μ s, floating-point calculation 0.24 μ s (about 33 times faster than standard CJ1H). The interrupt response time is 40 μ s, and the I/O refresh time is halved (1.4 μ s for 16 point input units). Supports three types of timed interrupt units: 0.1ms, 1ms, and 10ms.

Standard type (CJ1H-CPU □□ H): Basic instruction 0.02 μ s, special instruction 0.06 μ s.

2.2 CJ1M CPU unit (compact built-in I/O type)

Model Built in I/O Program Capacity Pulse Output PWM Output Expansion Rack

CJ1M-CPU23 has 20K steps, 2 channels, 100kHz, 2 channels, and 1 channel

CJ1M-CPU22 has 10K steps, 2 channels, 100kHz, and 2 channels, none

CJ1M-CPU21 has 5K steps, 2 channels, 100kHz, and 1 channel, none

CJ1M-CPU13 without 20K steps -1

CJ1M-CPU12 without 10K steps - none

CJ1M-CPU11 without 5K steps - none

Built in I/O function:

10 point input (IN0~IN9), adjustable input time constant (0~32ms)

6-point transistor output (OUT0~OUT5)

4-point interrupt input (IN0~IN3), response time 0.3ms

2-channel high-speed counter (differential phase 30/50kHz, single-phase 60/100kHz)

2-channel 100kHz pulse output (supports CW/CCW or pulse+direction)

2-channel PWM output (CJ1M-CPU21 only has 1 channel)

Fast response input (minimum pulse width of 30 μ s)

2.3 CJ1 CPU Unit (Economy Type)

Model I/O Points Program Capacity Data Memory Basic Instruction Time

CJ1G-CPU45 1280 60K steps 128K words 0.08 μ s

CJ1G-CPU44 1280 30K steps 64K words 0.08 μ s

Selection suggestion: When high-speed processing and rich communication functions are needed, choose CJ1H-R; When compact size and positioning/counting function are required, choose CJ1M (built-in I/O); Choose CJ1G for simple logic control and cost sensitivity.

System configuration and installation points

3.1 Rack Configuration

The CJ series does not require a base plate, and units are directly connected through side connectors. A CPU rack can accommodate up to 10 units (including power supply, CPU, and I/O units). Through the I/O control unit (CJ1W-IC101) and I/O interface unit (CJ1W-II101), up to 3 expansion racks can be connected (CJ1M only has 1). Each expansion rack can also have a maximum of 10 units.

Important: The terminal cover (CJ1W-TER01) must be installed on the far right side of the rack, otherwise an I/O bus error (A40114 ON, A404 displays 0E hex) may occur.

3.2 Selection of Power Supply Unit

Model Input Voltage 5V Output 24V Output Total Power Replacement Notice RUN Output

CJ1W-PA205R 100-240V AC 5.0A 0.8A 25W None

CJ1W-PA205C 100-240V AC 5.0A 0.8A 25W Yes No

CJ1W-PA202 100-240V AC 2.8A 0.4A 14W None None

CJ1W-PD025 24V DC 5.0A 0.8A 25W None None

CJ1W-PD022 24V DC 2.0A 0.4A 19.6W None None (Non insulated type)

Replacement notification function (CJ1W-PA205C): The 7-segment LED on the front panel displays the remaining lifespan (FUL → HLF → 1.5 → 1.0 → 0.5 → 0.0/A02). When the remaining lifespan is less than 6 months, the display alternates between "0.0" and "A02", and the alarm output (normally open contact) is disconnected. The TEST switch can temporarily test the alarm output.

Current consumption calculation: Calculate the total current of all units in the 5V and 24V groups, which must not exceed the power supply capacity. For example, the CPU unit is approximately 0.91~0.99A (5V), the 16 point input unit is approximately 0.08A, and the 32 point output unit is approximately 0.14A. The total power=5V total current x 5+24V total current x 24 ≤ the maximum power of the power supply.

3.3 DIN rail installation

All CJ units must be installed on DIN rails (direct screw installation is not supported). Use PFP series guide rails (50cm or 100cm) and fix both ends with end plates (PFP-M). When installing, first release the installation buckle on the back of the unit, insert the upper edge of the guide rail, and then press the lower edge of the unit to lock the buckle.

3.4 Extended Connection

The I/O control unit must be installed adjacent to the right side of the CPU unit. The I/O interface unit must be located immediately to the right of the power unit in the expansion rack. Use CS/CJ series I/O connection cables (CS1W-CN313/713/223/323/523/133, etc., length 0.3~12m), with a total cable length of no more than 12m. The connectors have directionality, and a "click" locking sound should be heard after insertion.

Practical experience of memory and I/O allocation

4.1 Overview of I/O Memory Region

Regional address range, size, and purpose

CIO area (I/O) CIO 0000~0079 80 word basic I/O unit allocation (expandable to CIO 0999)

Data Link Area CIO 1000~1199 200 Word Controller Link Data Link

CPU bus unit area CIO 1500~1899 400 words, 25 words per unit, a total of 16 units

Special I/O unit area CIO 2000~2959 960 words, 10 words per unit, a total of 96 units

Built in I/O area (CJ1M) CIO 2960~2961 2-word fixed allocation

Serial PLC link area CIO 3100~3189 90 word CJ1M dedicated

Fixed allocation of 600 words for CIO 3200~3799 in DeviceNet area

Internal I/O area CIO 1200~1499, 3800~6143 2644 word workspace

Workplace (W) W000~W511 512 word recommended priority workspace

Maintain zone (H) H000~H511 512 word power-off hold

Auxiliary Area (A) A000~A959 960 Word System Signs and Status

Timer area T0000~T4095 4096 timer completion flags and PVs

Counter area C0000~C4095 4096 counter completion flags and PVs

DM area D00000~D32767 32K character unit data

EM area (CJ1/CJ1H) E0_00000~EC_32767 maximum 13 × 32K word extended data memory

4.2 I/O allocation method

The CJ series offers two I/O allocation methods:

Automatic power on allocation (default): I/O words are allocated from left to right based on the actual installed units each time power is turned on. Adding or removing units can cause changes in I/O addresses, so it is important to pay attention to program adaptation.

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.

Replacement steps:

Power on the CPU for at least 5 minutes (charge the capacitor).

Disconnect the CPU power supply.

Open the battery compartment cover and carefully remove the old battery.

Unplug the battery connector and insert a new battery.

Reinstall the battery and close the compartment cover.

Notes:

It must be completed within 5 minutes after power failure, otherwise RAM data may be lost.

After replacement, clear the battery error through programming device (A40204 reset).

It is strictly prohibited to short-circuit, charge, disassemble or burn batteries.

6.3 Precautions for Flash Backup

The CJ1-H/CJ1M CPU automatically writes user programs and parameters to internal flash memory during the following operations:

Download the program through CX Programmer

Transfer programs through storage cards

Online editing

Never turn off the power when the BKUP indicator light is on, otherwise the data may be damaged.