snp.h File Reference

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

#include "ServerConfig.h"
#include <stddef.h>
#include <stdint.h>

Go to the source code of this file.

Detailed Description

GE Fanuc SNP (Series Ninety Protocol) serial frame codec (DETWS_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 an arithmetic-sum BCC (the low byte of the sum of every framed byte). 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.