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What This Appendix
Contains
Basic Format of Explicit
Messages
109
DeviceNet Explicit Messages
This appendix lists DeviceNet explicit messages sent from the master
unit to a safety I/O module that you can use to read or write any
parameter of a specified safety I/O module. The safety I/O module
processes the commands sent from the master and then returns
responses.
The basic format of each command and response is as follows.
Command Block
Destination Node
Service Code Class ID
Address
• Destination Node Address - The node address of the module
that is sending the explicit messages is specified with a 1 byte
hexadecimal.
• 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 block information is as follows.
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.
Instance ID
Source Node Address
Service Code
Source Node
Service
Address
Code
Publication 1791DS-UM001H-EN-P - April 2009
A
Appendix
Attribute ID
Data
Data
Error Code
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