MagTek MCP - Manual (Page 18)

MCP Serial Transport Protocol
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Request S-frames are sent by a node to request a specific transmission control operation to be
performed by the destination node. The destination node replies with a response S-frame within
a pre-determined amount of time. The response S-frame always has the same command code as
the request S-frame.
Each node may only have one pending S-frame request at any time; a node can not send a second
S-frame request until the previous one has completed (by receiving the appropriate S-frame
response).
Command Code (CC)
The command code specifies which transmission control operation should be performed. Each
command will be defined later in this document.
Data field of S-frames
S-frames may contain a data field. The meaning of the data field depends on the command code.
All response S-frame types have a data field. The first byte of the data field is always the result
code. Response S-frame types may have further command dependent information in the data
field. The result codes are defined as follows:
Result Code(Hex) Description
0 Success
1 Failure
2 Unsupported
3-FF RFU