Advantech USB-4751, User Manual

USB-4751/4751L  User Manual

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3.4  Field Wiring Considerations

•  When you use USB-4751/4751L to acquire data from outside, noises in 

the environment might significantly affect the accuracy of your mea-
surements 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-4751/4751L.

•  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. Or place the signal cable in a right angle to the 
power line to minimize the undesirable effect.