Detailed Description

NEMA TS 2 traffic-cabinet SDLC frame codec (DETWS_ENABLE_NEMA_TS2).

NEMA TS 2 links the devices inside a traffic-signal control cabinet - the controller, the Malfunction Management Unit (MMU), the Bus Interface Units (BIUs) and detector racks - over a synchronous SDLC bus. Each transaction is an SDLC frame:

[address][control][frame-type][data...][FCS-16]

where the FCS is the HDLC/X.25 CRC-16 (CRC-16/X-25: reflected poly 0x1021, init 0xFFFF, xorout 0xFFFF) over address..last-data, transmitted low byte first. This builds and validates those frames (the frame-type identifies command / status / detector frames per the TS 2 frame set); the synchronous serial PHY and the BIU/detector timing are the hardware-gated part. Pure, zero heap, host-testable.

Definition in file nema_ts2.h.