Some legacy Pamux Systems are still in use today, valued for their high-speed reading and writing of discrete I/O. Pamux Systems use the open Pamux protocol and are controlled by a custom program running on a PC, a motion controller, or other control equipment. Communications are over a parallel ribbon cable, and a PC requires a Pamux adapter card. 

A Pamux System includes a brain (I/O processor), I/O, and mounting rack, plus a software development kit and an adapter card for writing or changing a custom program.


Introduced in 1981, Opto 22's legacy Pamux® system was the first addressable, expandable, computer-based I/O system.

Pamux was capable of multiplexing hundreds of points of discrete I/O from a single microprocessor parallel port. Its high-speed read and write capabilities, coupled with the increased performance of microprocessors, made it possible to use computer-based control in large system-oriented applications.

Compatible brains, I/O, and racks

B4, a 32-channel Pamux digital brain, with the following I/O and racks:

B5, a 16-channel Pamux digital brain, with any of the following I/O and racks:

SNAP-B4, a 32-channel Pamux digital brain, with SNAP I/O and any SNAP B-series rack, for example the SNAP-B8M.

Analog I/O with Pamux

Pamux was also made available for analog signals, although the speed advantage of Pamux for digital is not realized with analog. Compatible products:

  • B6, a 16-channel analog brain (now obsolete) and G1 analog I/O with a PB4AHPB8AH, or PB16AH mounting rack
  • SNAP-B6 32-channel analog and digital brain (obsolete) and SNAP I/O

Compatible SDKs and adapter cards

PC-PAMUX-SDK for use with:

Adapter Card Toolkit for use with ISA bus: AC28 adapter card