Advantech PCIE-1756H, User Manual

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PCIE-1756H User Manual 20
Figure 3.6 Wiring in dry contact input mode
3.4 Field Wiring Considerations
When you use PCIE-1756H cards to acquire data from outside, noises in the environ-
ment might significantly affect the accuracy of your measurements if due cautions are
not taken. The following measures will be helpful to reduce possible interference run-
ning signal wires between signal sources and the PCIE-1756H card.
 The signal cables must be kept away from strong electromagnetic sources such
as power lines, large electric motors, circuit breakers or welding machines,
since they may cause strong electromagnetic interference. Keep the analog sig-
nal cables away from any video monitor, since it can significantly affect a data
acquisition system.

If the cable travels through an area with significant electromagnetic interference,
you should adopt individually shielded, twisted-pair wires as the analog input
cable. This type of cable has its signal wires twisted together and shielded with
a metal mesh. The metal mesh should only be connected to one point at the sig-
nal source ground.
 Avoid running the signal cables through any conduit that might have power lines
in it.
 If you have to place your signal cable parallel to a power line that has a high
voltage or high current running through it, try to keep a safe distance between
them. Alternatively, you can place the signal cable at a right angle to the power
line to minimize the undesirable effect.
 The signals transmitted on the cable will be directly affected by the quality of the
cable. In order to ensure better signal quality, we recommend that you use the
PCL-10250 or PCL-101100M shielded cable.