Appendix C Explicit Messages; Basic Format Of Explicit Messages - Omron CJ1W-PNT21 Operation Manual

C-1

Basic format of explicit messages

Explicit messages sent from the IO Controller Unit to a GRT1 Series PROFINET IO Communication Unit can be
used to read or write any parameter of a specified GRT1 Series PROFINET IO Communication Unit.
The PROFINET IO Communication Units process the commands sent from the Controller and then return
responses.
The basic format of each command and response is shown below.
/i
Command Block
Destination station Service
address code
Destination station address
The station address of the Unit that is sending the explicit messages (commands) is specified as a single-byte
hexadecimal number.
Service code, Class ID, Instance ID, Attribute ID
The parameters used for specifying the command, processing object, and processing content.
Data
Data is not required when the Read command is used.
Response blocks
/i
Normal Response Block
Number of bytes received
/i
Error Response Block
Number of bytes received:
0004 Hex (fixed)
Number of bytes received
The number of bytes received from the source station address is returned in hexadecimal. When an error
response is returned for an explicit message, the number of bytes is always 0004 Hex.
Source station address
The station address of the Unit from which the command was sent is returned in hexadecimal.
Appendix C
Explicit messages
Class Instance
ID ID
Note The number of bytes designated for Class ID, Instance ID, and Attribute ID depend on
the Controller Unit. When sent from an OMRON Controller, the Class ID and Instance
ID are 2 bytes (4 digits), and Attribute ID is 1 byte (2 digits).
Source station address
Source station address
Attribute Data
ID
Service code Data
Service code Error code
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