Rockwell Automation 2100-GK61 DeviceNet to SCANport - Manual (Page 109)

Publication 2100-UM001B-EN-P – January 2001
Using DeviceNet Explicit Messaging 6-17
The format of Request and Response messages is in Figure 6.9.
Figure 6.9
Format of DeviceNet Messages
For information on M-File locations, refer to the 1747-SDN
DeviceNet Scanner Module Manual, Publication 1747-5.8.
The message buffer is composed of two sections:
• Transaction header — three words that contain information
identifying the message transaction.
• Transaction body — in a request, this contains the DeviceNet
Class, Instance, Attribute, and Service Data portions of the
transaction. See Appendix C. In a response, this contains the
Service Data only.
Format of 32-word M0-file
Write of Explicit Message Request
Format of 32-word M1-file
Read of Explicit Message Response
15 0 15 0
Transaction
Header (3
words) TXID COMMAND TXID STATUS word 0
PORT SIZE PORT SIZE
SERVICE MAC ID SERVICE MAC ID
Transaction
Data (up to 29
words) CLASS SERVICE RESPONSE DATA
INSTANCE "
ATTRIBUTE "
SERVICE DATA "
" " word 31