Programmable controller with modular firmware for communication control

A programmable controller module (PCM) for operably coupling a plurality of peripheral devices (PDs) of various communication disciplines to a data processor (DP) or to remote PCMs through a serial interface adapter (SIA) or parallel interface adapter (PIA). The PCM is comprised of a special purpose computer having a program of subroutines arranged in memory modules which define and implement specific communication protocols (routines) for different communication disciplines. Each PD connected to a PCM by an SIA or PIA is assigned a channel code and is addressed by channel code. A discipline identification (DID) line is connected from each adapter channel to one of a predetermined number of terminals in the PCM. There is one terminal for each communication discipline for which there is stored in a memory module an appropriate protocol. Each channel has its DID line connected to the appropriate terminal according to the communication discipline of the PD connected to it. When a channel is addressed, its DID is activated. The PCM then scans the terminals to determine which is activated to ascertain the discipline of the device.