Advantech PCI-1711 Manuel d'utilisateur télécharger pdf (Page 33)

27 Chapter 3

3.4 Field Wiring Considerations

When you use PCI-1711U cards to acquire data from outside, noises in

the environment might significantly affect the accuracy of your measure-

ments if due cautions are not taken. The following measures will be help-

ful to reduce possible interference running signal wires between signal

sources and the PCI-1711U 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 inter-

ference. Keep the analog signal 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 signal 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 dis-

tance 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 recom-

mend that you use the PCL-10168 shielded cable.

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Advantech PCI-1711 Manuel d'utilisateur Page 33