Rockwell Automation 1790P-4R0 CompactBlock LDX I/O RTD/Resistance Input Module - Manual (Page 23)

Publication 1790-UM002A-EN-P
Installation and Wiring 2-11
Field Wiring
Connections System Wiring Guidelines
Consider the following when wiring your system:
General
•
This product is intended to be mounted to a well-grounded mounting
surface such as a metal panel. Additional grounding connections from
the module’s mounting tabs or DIN rail (if used) are not required
unless the mounting surface cannot be grounded.
•
Route field wiring away from any other wiring and as far as possible
from sources of electrical noise, such as motors, transformers,
conductors, and ac devices. As a general rule, allow at least 15.2 cm (6
in.) of separation for every 120V of power.
•
Routing field wiring in a grounded conduit can reduce electrical noise.
•
If field wiring must cross ac or power cables, ensure that they cross at
right angles.
•
To ensure optimum accuracy, limit overall cable impedance by
keeping your cable as short as possible. Locate the I/O system as
close to your sensors or actuators as your application will permit.
•
Tighten terminal screws with care. Excessive tightening can strip a
screw.
Shield Grounding
•
Use Belden shielded, twisted-pair wire to ensure proper operation
and high immunity to electrical noise. Refer to the following table and
the RTD Wiring Considerations below.
•
Under normal conditions, the drain wire and shield junction should be
connected to earth ground, via a panel or DIN rail mounting screw at
the module end.
•
Keep shield connection to ground as short as possible.
•
If noise persists for a device, try grounding the opposite end of the
cable. (You can only ground one end at a time.)
•
Refer to Industrial Automation Wiring and Grounding Guidelines,
Allen-Bradley publication 1770-4.1, for additional information.
Table 2.4 Belden Shielded Wiring
Configuration
Recommended Cable
(1)
2-wire Belden™ 9501 or equivalent
3-wire
less than 30.48 m (100ft.) Belden 9533 or equivalent
3-wire
greater than 30.48 m (100 ft.) or high humidity conditions Belden 83503 or equivalent
(1) For additional information, see Table 2.5.