Rockwell Automation 1756-XXXX ControlLogix Analog I/O Modules - Manual (Page 137)

Publication 1756-UM009C-EN-P - December 2010 137
Temperature-measuring Analog Modules (1756-IR6I, 1756-IT6I, and 1756-IT6I2) Chapter 6
Field-side Circuit Diagrams
The diagrams show field-side circuitry for the 1756-IR6I, 1756-IT6I, and
1756-IT6I2 modules.
1756-IR6I Input Circuit
1756-IT6I and 1756-IT6I2 Input Circuit
43497
lexc
Rwire (A)
A/D converter
Vref
Gain = 1
IN-0/A
RTN-0/C
V_RTD + 2 (Vwire)
3-Wire RTD
Gain = 2
Rwire (C)
IN-0/B
lexc
Vwire = lexc x Rwire
V_RTD + 2 (Vwire) - 2Vwire = V_RTD
594
μ
A Excitation
Current (All Ranges)
Rwire for cable B has no effect
because B is a Sense wire with
zero excitation current.
43498
IN-0/A
RTN-0/C
+0.44 V
0.22
μ
F
383
A/D converter
Vref
0.002
μ
F
Gain = 30
20 M
Ω
25 K 5 K
-12 to 78mV
+2.5V
1.96 K