Omron SYSMAC CJ1W-EIP21 - Manual (Page 283)

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Receiving Explicit Messages Section 9-2
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 that will read the data is specified
as shown in the following table.
Address L, Address H (command): The address of the first word from which
to read the data is specified in hexadecimal as shown below.
Address L: The lower 2 digits when the first word address is given in 4-digit
hexadecimal.
Address H: The higher 2 digits when the first word address is given in 4-digit
hexadecimal.
No of Read Bytes (command): The number of bytes of read data is specified
in 1-byte (2-digit) hexadecimal. The range is 01 to C8 Hex (1 to 200 decimal).
No. of bytes received (response): The number of bytes received from the
destination node address (remote node) is returned in hexadecimal.
Destination node address (response): The node address of the CS/CJ-
series EtherNet/IP Unit or built-in EtherNet/IP port that returned the response
is returned in hexadecimal.
Read data (response): The specified area, word, and byte data is returned in
order from word H (high byte: bits 8 to 15) to word L (low byte: bits 0 to 7). If
an odd number is specified for the number of read bytes, the last 1 byte of
data will be read to the high word.
Important Points The actual address L, address H, and number of read bytes that can be spec-
ified depends on the model of the CPU Unit, and the data area being read. Do
not exceed the boundary of the data areas for the PLC you are using.
Word Data Read (Service Code: 1D Hex)
Word Data Read reads I/O memory area data in a CPU Unit. The read word
data is in word units. The response block data is returned in low-to-high byte
order.
Command Block
Note A body format of either 8 bits or 16 bits is possible.
Instance ID (Hex) CPU Unit memory area
for read
Word range
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)
C4
(2F)
(*) (*)
1D
Service
Code
No. of words read
Class ID
Instance ID
Address L
Address H
The class ID depends on the unit version.
Version 2.0: The class ID is C4.
Version 1.0: The class ID is 2F.