Temperature Control Using a BTM Module in an SLC System

The temperature control module is an intelligent I/O module that can 

provide a maximum of 4 PID loops for temperature control. The 

module has 4 analog thermocouple (TC) inputs. Each analog input 

functions as the process variable (PV) for a PID loop. The PID 

algorithm and tuning–assisted–process (TAP) algorithm are performed 

on the module for each of the loops. The control–variable (CV) 

output of each loop, either analog output or time–proportioned 

output (TPO), is sent from the module to the SLC data table. Your 

application ladder logic must access the CV value in the data table and 

send the analog or TPO data to an output module to close the loop.

Features of the Temperature Control Module

The 1746–BTM module provides:

• 4 independent temperature control loops

• autotune PID loops (one loop or any combination of loops can 

be autotuned while other loops are running)

• a unique start–up algorithm to minimize overshoot

• an isolated thermocouple (J and K) input for each PID loop

• 16–bit analog–to–digital converter resolution (0.1° resolution)

• a heat CV signal (for each PID loop) as a numeric % value

• a cool CV signal (for each PID loop) as a numeric % value

• a heat CV signal (for each PID loop) as a TPO bit

• a cool CV signal (for each PID loop) as a TPO bit

• temperature values in C ° or F °

• self–calibration (external reference required)

• user–selectable high and low alarms with dead band for hysteresis

• input open–circuit detection