Technical data

Publication 1794-2.1 - January 2000
FLEX I/O and FLEX Integra Product Data
24V dc Thermocouple/mV Input Module Cat. No. 1794-IT8 129
24V dc Thermocouple/mV Input Module Cat. No. 1794-IT8
Wiring
1. Connect the individual high and low signal wiring to numbered
terminals on the 0-15 row (A) on the terminal base unit as
indicated in the table below.
2. Connect 24V dc common to terminal 16 on row (B).
3. Connect individual channel shield returns to the associated
terminal on row (B) for 1794-TB3 or row (C) for the 1794-TB3T as
shown in the table below.
4. Connect +24V dc to terminal 34 on the 34-51 row (C).
5. If daisy-chaining 24V dc common, connect jumper from terminal 33
to terminal 16 on the next terminal base unit.
6. If daisy-chaining +24V dc, connect jumper from terminal 51 to
terminal 34 on the next terminal base unit.
7. Connect the shield to functional earth ground as near as possible to
the module.
Recommended
Terminal Base
Compatible
Terminal Base(s)
1794-IT8
THERMOCOUPLE INPUT 8 CHANNEL
-++-+
-
+-
3
-++-+
-
+-
INPUT 0 INPUT 1 INPUT 2 INPUT 3
INPUT 4 INPUT 5 INPUT 6 INPUT 7
OK
40149
TB3T TB3 TB3S TB2 TB3TS
You can use a TB2,
TB3, or TB3S for
mV inputs only.
40150
Simplified Schematic Channel 0 TB3T or TB3TS shown
Input Device
Cold Junction
Sensor
Cold Junction
Sensor
24V
Power Supply
Shielded
Twisted Pair
Cable
A-0
A-1
C-39
C-36
C-37
C-38
C-47
C-48
C-49
C-34
B-16
dc/dc
Converter
A/D
Converter
Voltage
Resistance
A/D
Converter
Micro
Processor
Flexbus
Interface
Opto
Isolation
+5V +5V
+5V
Flex
bus
+5V
-5V
+15V
-15V
ATTENTION
!
To reduce susceptibility to noise, power analog
modules and digital modules from separate power
supplies. Do not exceed a length of 10m (33ft) for dc
power cabling.
Do not daisy chain power or ground from the RTD
terminal base unit to any ac or dc digital module
terminal base units.
ATTENTION
!
Total current draw through the terminal base unit is
limited to 10A. Separate power connections to the
terminal base unit may be necessary.