profibus.h File Reference

PROFIBUS-DP FDL telegram codec (DETWS_ENABLE_PROFIBUS). More...

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

Go to the source code of this file.

Detailed Description

PROFIBUS-DP FDL telegram codec (DETWS_ENABLE_PROFIBUS).

PROFIBUS-DP is the Siemens RS-485 master/slave fieldbus (the DP-V0 cyclic I/O exchange). Its FDL data link uses fixed telegram formats delimited by a start byte (SD):

• SD1 (0x10): no data - SD1 DA SA FC FCS ED (a request/status telegram).
• SD2 (0x68): variable data - SD2 LE LEr SD2 DA SA FC [data...] FCS ED, where LE = length of (DA + SA + FC + data), repeated as LEr for redundancy.
• SD3 (0xA2): fixed 8 data bytes (not built here).

DA = destination, SA = source, FC = frame control. The FCS is the arithmetic sum (mod 256) of DA + SA

• FC + data. ED (end delimiter) is 0x16. This builds/validates the SD1 and SD2 telegrams a DP master exchanges with slaves; the RS-485 UART timing + the DP-V0 state machine are the device step. Pure, zero heap, no stdlib, host-testable.

Definition in file profibus.h.