Appendix 1: Devicenet Explicit Messages; A-1-1 Basic Format Of Explicit Messages - Omron DeviceNet DST1 Series Operation Manual

Appendix 1: DeviceNet Explicit Messages

Appendix 1: DeviceNet Explicit Messages
DeviceNet explicit messages sent from the Master Unit to the DST1-series Safety I/O
Terminals can be used to read or write any parameter of a specified DST1-series Safety
I/O Terminals. The DST1-series Safety I/O Terminals processes the commands sent
from the master and then returns responses.
A-1-1 Basic Format of Explicit Messages
The basic format of each command and response is shown below.
Command Block
Destination node
address
Destination Node Address
The node address of the Unit that is sending the explicit message is specified with on
hexadecimal byte.
Service Code, Class ID, Instance ID, and Attribute ID
The parameters used for specifying the command, processing object, and processing
content.
Note: The number of bytes designated for the class ID, instance ID, and attribute ID depend on
the Master Unit. When sent from an OMRON DeviceNet Master, the class ID and instance
ID are 2 bytes (4 digits) each, and the attribute ID is 1 byte (2 digits).
Data
Data is not required when a read command is used.
Response Block
Normal Response Block
Number of bytes received
Error Response Block
Number of bytes received
0004 hex (fixed)
Number of Bytes Received
The number of bytes received from the source node address is returned in hexadecimal.
When an error response is returned for an explicit message, the number of bytes is
always 0004 hex.
Source Node Address
The node address of the node from which the command was sent is returned in
hexadecimal.
A-2
Service Class Instance
code ID ID
Source node
Service code
address
Source node
Service code Error code
address
Attribute Data
ID
Data