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OEM-AT6400 Installation Guide
I/O Cables
Bear in mind that the length of the cables is directly related to noise sensitivity; lengthening
cables increases noise sensitivity. The maximum length of cables is ultimately determined by
the environment in which the equipment will be used. (The optional VM60 screw terminal
includes a 5 foot long ribbon cable.)
The input and output lines on the OEM-AT6400 are not optically isolated. The state of the
ground plane in most PCs can leave the OEM-AT6400 susceptible to ground-loop noise.
Follow the precautions below to minimize noise problems.
• Use a minimum wire size of 22 AWG.
• Use twisted pair shielded cables and connect the shield to a
SHLD
pin (pins 58 and 60) on
the 60-pin connector. Leave the other end of the shield disconnected.
• Do not route I/O signals in the same conduit or wiring trays as high-voltage AC wiring
or motor wiring.
• Provide some form of isolation for the I/O, preferably optical isolation, to reduce the
effects of noise in your system.
Reducing noise on limit and trigger inputs. If you are experiencing noise
problems, try adding resistors to reduce noise sensitivity (see illustration below).
Long Cable
Add a resistor between the input and the power supply (this will lower
the input impedance and reduce noise sensitivity). Use a value
between 330
Ω
and 2.2K
Ω
, depending on noise suppression required.
External Power Supply
(5-24VDC)
Output Device,
Switch, etc.
5V
AUX-P
Input Terminal
(Limits or Trigger)
GND
Shield
OEM-AT6400
Power Supply Options
See Appendix A for additional information about reducing electrical noise.
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