The SERIPLEX control bus is a deterministic, serial multiplexed, bit-level sensor network designed to connect IO devices to a PLC over a dedicated 4-wire cabling system. It provides both master/slave and peer-to-peer control. It was introduced around 1987, and was developed by Automated Process Control, Inc.
Devices using the Seriplex ASIC were introduced by Square D, Turck, Banner, and others.