Rockwell Automation 1732E-IR4IM12R ArmorBlock Dual-Port EtherNet/IP 4-Point Thermocouple and RTD - Manual (Page 12)

4 Rockwell Automation Publication 1732E-UM004A-EN-E - July 2012
Chapter 1 Overview of the 1732E ArmorBlock Thermocouple and RTD Input Modules
• Enter an estimated temperature (Cold Junction Compensation Offset).
• Use external cold junction compensators to measure the cold junction
temperature directly.
To compensate for cold junction temperature voltage, the 1732E-IT4IM12R
Thermocouple module has to determine actual cold junction temperature. If the
module is configured to provide cold junction compensation, then the user must
use a CJC Terminal Chamber (such as Allen-Bradley 871A-TS4CJC-DM or
871A-TR4CJC-DM
(1)
as shown in the next diagram).
The module uses this thermistor(s) resistance to deduce the cold junction
generated voltage to be applied to accurately measure the hot junction absolute
temperature.
The compensation voltage to be applied can also be estimated by applying fixed
cold junction correction using a fixed offset directly through the RSLogix 5000
software. The module supports thermistor compensation range at 0…70 °C.
The Thermocouple module also supports CJC error detection if a channel CJC
module is selected but is not correctly connected to the correct channel. The
module detects open circuit condition and triggers the warning status bit and
fault LED.
Cold junction compensation is supported on all four channels of the
1732E-IT4IM12R module.
RTD Sensor Types The 1732E-IR4IM12R module supports 100
Ω
- 200
Ωμ
= 0.00385/0.003916 Pt
RTDs, 100/120
Ω
Ni RTDs, and a 10
Ω
Cu
α
=0.00427 RTD.
(1) The Allen-Bradley 871A-TS4CJC-DM or 871A-TR4CJC-DM terminal chamber has an embedded thermistor,
which facilitates thermocouple-based temperature measurement. The thermistor types supported are
Thermometrics MF65F302V/W, or DC95F302V/W.
Thermistor resistance used by the module to
determine a baseline for the thermocouple
Thermocouple
Hot junction
Cold junction
Face of module connector
871A-TS4CJC-DM or 871A-TR4CJC-DM
Terminal Chamber shown