snp.h File Reference

GE Fanuc SNP (Series Ninety Protocol) serial frame codec (PROTOCORE_ENABLE_SNP). More...

#include "protocore_config.h"

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Detailed Description

GE Fanuc SNP (Series Ninety Protocol) serial frame codec (PROTOCORE_ENABLE_SNP).

SNP is the GE Fanuc Series 90 (90-30 / 90-70) master-slave serial protocol over RS-485. A message is a BCC-checked frame delimited by control characters:

[SOH-or-other-control][data...][checksum]

SNP frames the payload with an ASCII/binary control byte, a length, the data, and the Block Check Code of GE Fanuc GFK-0582D p. 7-62 (seed zero; per byte, XOR then rotate the accumulator left one bit). This builds/validates that frame so a device can read/write registers on a Series 90 PLC; the RS-485 UART transport (and the SNP-X session setup) is the remaining device step. Pure, zero heap, no stdlib, host-testable.

Definition in file snp.h.