Rockwell Automation 1769-IT6 Compact I/O Thermocouple/mV Input Module - Manual (Page 11)

Compact I/O Thermocouple/mV Input Module 11
Publication 1769-IN026C-EN-P - February 2010
6. Before installing the replacement module, be sure that the bus levers on the module
to be installed and on the right-side adjacent module are in the unlocked (fully right)
position.
7. Slide the replacement module into the open slot.
8. Connect the modules by locking (fully left) the bus levers on the replacement module
and the right-side adjacent module.
9. Replace the mounting screws (or snap the module onto the DIN rail).
Wire the Thermocouple/mV Input Module
Consider these system wiring guidelines when wiring your system:
• Do not use the module’s NC terminals as connection points.
• Do not tamper with or remove the CJC sensors on the terminal block. Removal of
one or both sensors will reduce accuracy and set the open-circuit bit for that CJC
sensor.
• For thermocouple inputs, always use shielded, twisted-pair thermocouple extension
lead wires specified by the thermocouple manufacturer for the thermocouple type
you are using. Using the incorrect thermocouple extension wire type or not following
correct polarity convention will cause invalid readings.
• Keep the cable shield connection to ground as short as possible.
• To limit noise, keep thermocouple and millivolt signal wires as far away as possible
from power and load lines as well as other sources of electrical noise, such as motors,
transformers, contactors, and AC devices.
• If the field wiring must cross AC or power cables, be sure that they cross at right
angles.
• For millivolt inputs, always use Belden 8761 (shielded, twisted-pair) or equivalent wire
to be sure of proper operation and high immunity to electrical noise.
• If multiple power supplies are used with millivolt analog inputs, the power supply
commons must be connected.
ATTENTION
The possibility exists that grounded or exposed thermocouples can become shorted to a
potential greater than that of the thermocouple. Due to possible shock hazard, take care
when wiring these types of thermocouples.