MagTek MCP - Manual (Page 24)

MCP Serial Transport Protocol
18
Frame Reject Command
Command Code: 5 (0101)
S-frame Type: Indication
PCB: 85 (Hex)
Description:
The frame reject command is used to notify another node on the network that a frame they sent
was not valid (e.g. unsupported EDC type). Frame rejection is used on frames that are
understood by the receiver but contain unsupported types or data. For example, the frame may
specify an unsupported frame type or may contain an invalid status code. In this case the frame
passed error detection validation and was received correctly but contained invalid data. The
frame reject command is an indication. It does not require a response from the recipient. If a
node decides to respond to the indication, it must send a frame different than the frame
previously sent. The use of the command is optional. The command’s sole purpose is to speed
up error recovery.
Data:
The structure of the data field of this indication is defined as follows:
PCB ETYP
• PCB
PCB field of the invalid frame
• ETYP type of error detected (unsupported frame type, unsupported EDC type, …)
The type of error can be one of the following:
ETYP Definition
0 Unsupported frame type.
1 Unsupported S-frame command.
2 Chaining not supported.
3 Frame is too long.
4 Message is too long.
5 EDC type error.
6 Communication error on the bus.
7 Abort chain.