Artesyn ATCA-9305 User's Manual (May 2014) - Manual (Page 142)

System Management
ATCA-9305 User’s Manual (10009109-07) 142
7.4 IPMB Protocol
The IPMB message protocol is designed to be robust and support many different physical
interfaces. The IPMC supports messages over the IPMB interface. Messages are defined as
either a request or a response, as indicated by the least significant bit in the Network Function
Code of the message.
 The first byte contains the responder’s Slave Address, rsSA.
 The second byte contains the Network Function Code, netFn, and the responder’s Logical
Unit Number, rsLUN.
 The third byte contains the two’s-complement checksum for the first two bytes.
 The fourth byte contains the requester’s Slave Address, rqSA.
 The fifth byte contains the requester’s Sequence Number, rqSeq, and requester’s Logical
Unit Number, rqLUN. The Sequence number may be used to associate a specific response
to a specific request.
 The sixth byte contains the Command Number.
 The seventh byte and beyond contain parameters for specific commands (if required).
 The final byte is the two’s-complement checksum of all of the message data after the first
checksum.
Table 7-3 Format for IPMI Request Message
Byte Bits
7 6 5 4 3 2 1 0
1 rsSA
2 Network Function (netFn) rsLUN
3 Checksum
4 rqSA
5 rqSeq rqLUN
6 Command
7:N Data
N+1 Checksum