focas.h File Reference

FANUC FOCAS Ethernet protocol codec (DETWS_ENABLE_FOCAS) - zero-heap request builders + response parsers for FANUC CNCs over TCP 8193 (the machine-tool data protocol). More...

#include "ServerConfig.h"

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Detailed Description

FANUC FOCAS Ethernet protocol codec (DETWS_ENABLE_FOCAS) - zero-heap request builders + response parsers for FANUC CNCs over TCP 8193 (the machine-tool data protocol).

FOCAS ("FANUC Open CNC API Specification") is normally a proprietary PC library (fwlib32); this is a pure codec for its Ethernet wire protocol. Every multi-octet field is BIG-endian. A frame is a 10-octet envelope + a payload:

envelope (10)
  A0 A0 A0 A0        frame magic
  version    (2)     = 1
  frame type (2)     0x0101 open req / 0x0102 open resp
                     0x2101 command (VAR) req / 0x2102 command resp
                     0x0201 close req / 0x0202 close resp
  length     (2)     octets of payload that follow
payload (length)     type-specific (see below)

The session is: open (payload = FRAME_DST 0x0002) -> one or more commands -> close. A command request payload is a 6-octet selector + five signed 32-bit arguments + optional extra data:

c1 c2 c3           three u16: the FOCAS function selector (e.g. 1/1/0x18 = SysInfo)
v1 v2 v3 v4 v5     five i32: the function's integer arguments
extra...           function-specific trailing bytes (none for the reads below)

A command response payload echoes the 6-octet selector, then a 6-octet status (a signed-short FOCAS return code in its first two octets, 0 = EW_OK), then a u16 data length, then the data.

Frame layout, selector encoding, the open/close handshake, the SysInfo (ODBSYS) and alarm (>L) response layouts, and the 8-octet value encoding (data / base^exp) were reverse- engineered by and cross-checked against diohpix/pyfanuc. Function selectors are the verbatim set documented there. Pure codec, host-tested - the caller owns the TCP connection (det_client_*) and drives the open -> command -> close sequence.

Author

Douglas Quigg (dstroy0)

Date

2026

Definition in file focas.h.