A-B 1746-BTM Barrel Temperature Control Module

The 1746-BTM module is compatible with any SLC processor that 

supports M0/M1 files, such as the SLC 5/05, SLC 5/04, SLC 5/03, and 

SLC 5/02 controllers.

Vocabulary

In this manual, we refer to:

• the barrel temperature control module as the “1746-BTM 

module,” the “BTM module,” or as “the module”

• the programmable controller as the “SLC processor”, or “the processor”

• a thermocouple as a “TC”

• a time-proportioned output as “TPO”

• the tuning-assisted processes as “TAP”

• proportional-integral-derivative as “PID”

• cold-junction compensation as “CJC”

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

Module Outputs

The BTM module sends the control variable (CV) for heating and/or 

cooling each loop to the SLC processor’s input image table as both of:

• numeric value (current CV)

• time–proportioned output (TPO)

Current CV

Your ladder logic should read the numeric value (current CV), scale it, 

and send it to an analog output module to generate the control signal 

to an analog temperature control actuator. If using the sample 

program look for current CVs in N10:208–211 for loops 1–4. 

TPO

The module returns the heat TPO (bit 6) and cool TPO (bit 7) in input 

image table words 8–11 for loops 1–4. The sample program sends 

TPO signals to a digital output module to generate the control signal 

to a digital temperature control actuator.