Appendices - Omron DST1-ID12SL-1 Operation Manual

Appendix 1: DeviceNet Explicit Messages
DeviceNet explicit messages sent from the Master Unit to the DST1-series Terminals can be used to read or
write any parameter of a specified Terminal. The DST1-series Terminal processes a command sent from the
Master Unit and then returns a response.
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.
Appendix
Service Class Instance
code
ID ID
Source node Service code
address
Source node Service code Error code
address
Attribute Data
ID
Data
137