Specifications

Minimizing EMI: System Design Guidelines Power-line Filtering
VisiLogic: Getting Started 11
Power-line Filtering
Some environments may induce greater EMI than the typical industrial
environment. Extra power and/or signal line filtering may improve the system’s
immunity to EMI.
If power-line filtering is required, please use the following guidelines in
addition to the guidelines provided by the filter manufacturer:
1. Use of power-line filters that comprise an earthing terminal is
recommended. Ground the filter earth terminal as explained in the section
Enclosing and Earthing.
2. Place the filter as close as possible to the target device(s). The maximum
wire length is 10 cm.
3. When using the EX-A1 expansion adapter:
4. Place one filter for both the PLC and the EX-A1 as instructed below.
Please note that you must use a single line filter for both the PLC and
EX-A1.
5. If the power-supply is closer to the PLC than it is to the EX-A1:
- Install and connect the power-line filter as close as possible to the PLC.
The maximum wire length is 10 cm. Please refer to the filter manufacturer
documentation for installation information.
- Create 0V and 24V junctions at the PLC respective terminals (see the
following figure) and directly connect the PLC main supply lines to the EX-
A1.
- Continue daisy-chaining the supply lines to the expansion I/O units.
Please ensure that the wire segment which carries the 0V between
the EX-A1 and the PLC does not branch.
When the power-supply is near the PLC, connect the PLC first as shown in
the next figure.