Rockwell Automation Samsung NX-CPU700p, User Manual, Page: 111 / 122

111
Structure of Communication Frames
The function code is explained with the example of Query and
Response frame based on the 2-step communication.
Query (Q) and Response (R) frame
Query Acknowledge (QA) frame
Response Request (RR) frame
Response (R) frame for an error
DA SA Function code Length Information CRC L CRC H
Length of information area
(byte)
1 to 255: 1 to 255 bytes
0: 256 bytes
Function code
Sender ID
Receiver ID
DA SA $80 01 00 CRC L CRC H
DA SA $00 01 00 CRC L CRC H
DA SA $8X 01 Error No CRC L CRC H
CRC-16 code
(2 bytes)
Constant
Error #1. Wrong communication function code
Error #2. Out of range
Error #3. Wrong frame structure
Error #4. CPU did not perform
Error #5. Frame is too long
The frame is sent from SA
to DA. After Q or RR is sent,
DA and SA for the QA and
R from the CPU are
replaced each other,
because the CPU becomes
the sender and the
peripheral device becomes
the receiver of the
message.
Constant