Advantech USB-4718 Manuel d'utilisateur télécharger pdf (Page 37)

31 Chapter 3

Figure 3.4: Isolated Digital Output Channel Connections

3.6 Field Wiring Considerations

• When you use USB-4718 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

helpful to reduce possible interference running signal wires between

signal sources and the USB-4718.

• 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.

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Advantech USB-4718 Manuel d'utilisateur Page 37