Omron CJ1W-EIP21 User Manual

Note A body format of either 8 bits or 16 bits is possible.

Service code (command, response): IF Hex is specified for commands. For
responses, the highest bit will turn ON and 9F Hex will be returned.

Class ID (command): Always C4 (2F).
The class ID depends on the unit version. The class ID is C4 for unit version
2.0, and 2F for unit version 1.0.

Instance ID (command): The memory area to which the data is written is
specified as shown in the following table.

Address L, Address H (command): The address of the first word to which
the data is written is specified in hexadecimal as shown below.
Address L: The lower 2 digits when the first word address is displayed in 4-
digit hexadecimal.
Address H: The higher 2 digits when the first word address is displayed in 4-
digit hexadecimal.

Write data (response): The specified area and write data is returned in order
from word L (lower byte: bits 0 to 7) to word H (higher byte: bits 8 to 15).

The actual address L, address H, and number of write data bytes that can be
specified depends on the model of the CPU Unit, and the data area being
written. Do not exceed the boundary of the data areas for the PLC you are
using.

Address L

Address H

Word data H

Word data L

Word data H

Write data (200 bytes max.)

Word data L

(*)

C4

(2F)

(*)

1F

Service
Code

Class ID

Instance ID

The class ID depends on the unit version.
Version 2.0: The class ID is C4.
Version 1.0: The class ID is 2F.

Service Code

9F

01

CIO

0000 to 6143

03

DM

D00000 to D32767

04

WR

W000 to W511

05

HR

H000 to H1535

08 to 20

EM, banks 0 to 18

En_00000 to En_32767 
(n: 0 to 18)