The Allen Bradley 1746-BTM is a Barrel Temperature Control Module for the SLC 500 system. It is an intelligent I/O module that accommodates four (4) zones of autotuned heat/cool PID loops for temperature control applications. Each of its 4 analog inputs functions as the controlled variable (C) for a PID loop. For each of the loops, a tuning-assisted process (TAP) algorithm and a PID algorithm are performed on the module; the manipulated variable (M) output of each loop, either as a numeric value or as a time-proportioned output (TPO) signal is sent from the module to the SLC processor’s data table. A ladder logic can send either the TPO signal to a digital output module or the M numeric value to an analog output module to close the loop. This unit uses a single slot for installation in an SLC 500 chassis and provides self-calibration, auto-tuning of PID loops (optimized for tuning barrel temperature control loops), self-diagnostics and detection of input open-circuit including thermocouple break. It is compatible with all SLC 500 processors except the SLC 5/01 processor.

This module is designed to provide four (4) Proportional-Integral-Derivative (PID) loops. Process Variable (PV) input is wired to any of the module’s four (4) Thermocouple input channels. Supported Thermocouple types of this module are Type J and K thermocouples. The module has configurable and intelligent response when broken sensor input is detected. Configurable responses are disabled loop, force CV to break TC break control value, force CV to manual % output or invalid setting. Decision for the TC break response must be based according to the process’ safe state during errors or Fail-Safe position. Additionally, the Barrel Temperature Control Module support configuration of loop alarm by enabling the appropriate alarm WORD and Bits.