Advantech PCI-1758 Series, User Manual

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PCI-1758 Series User Manual 20
Figure 3.8 Isolated Digital Output Connection
3.5 Field Wiring Considerations
When using PCI-1758 series cards to acquire data from an outdoor environment,
noises in the environment can significantly affect the accuracy of measurements if
due cautions are not taken. The following measures can help reduce possible inter -
ference on signal wires connecting signal sources to the PCI-1758 series card.

Signal cables must be kept away from strong electromagnetic sources, such as
power lines, large electric motors, circuit breakers, or welding machines, as
these may cause strong electromagnetic interference. Keep analog signal
cables away from any video monitors because they can significantly affect data
acquisition systems.

If signal cables are routed through an area with significant electromagnetic inter -
ference, users should employ individually shielded, twisted-pair wires as analog
input cables. This type of cable features 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 may also contain
power lines.

If the signal cable must be routed parallel to a high-voltage.current power line,
try to maintain a safe distance between the two cables. Alternatively, the signal
cable can be placed at a right angle to the power line to minimize the undesir -
able effect.