MagTek MCP - Manual (Page 38)

MCP Serial Transport Protocol
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Rule 6.2
If a node receives a RESEND S-frame indication for an outstanding I-frame and the PCB
enclosed in the RESEND indication matches the PCB of the outstanding I-frame, the node shall
either (a) ignore the indication or (b) initiate error recovery immediately, without waiting for the
block wait timeout to expire.
Rule 6.3
If a node receives a RESEND S-frame indication for an outstanding S-frame request and the
PCB enclosed in the RESEND indication matches the PCB of the outstanding S-frame request,
the node shall either (a) ignore the indication or (b) resend the S-frame request immediately,
without waiting for the block wait timeout to expire.
Rule 6.4
If a node receives a frame with correct EDC and incorrect PCB, the node shall either (a) ignore
the received frame or (b) send a REJECT S-frame indication, enclosing the PCB of the received
frame and specifying the “not supported” error code.
Rule 6.5
If a node receives a REJECT S-frame indication and the enclosed PCB is the PCB of an
outstanding I-frame or of an R-frame, the node shall either (a) ignore the indication, (b) consider
the connection dissolved, or (c) initiate reset of the connection.
Rule 6.6
If a node receives a REJECT S-frame indication and the enclosed PCB is the PCB of an
outstanding S-frame request, the node shall either (a) ignore the indication or (b) consider the
request failed.