Appendix A - Recommended Wiring Practices
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Appendix A: Recommended Wiring Practices for IDC Controls

When configuring your Impulse please follow the wiring practices listed below:
• Earth ground your machine at one point using a star configuration (shown at right).
Multiple earth grounds can cause a ground loop (see Preventing Ground Loop below).
• Avoid long cable runs. The longer the cables, the lower the signal-to-noise ratio in your
application.
• Use shielded motor and encoder cables along the entire cable run.
• Separate the signal wires (I/O, encoder, etc.) from the motor wires, AC power wires, and other
sources of noise in your application.
• Avoid extending cables in the field via junction boxes, terminal strips, or Molex connectors.
These types of connectors are typically unshielded (as is wire going into and out of the connec-
tor) and are places where noise may be injected into the system.
• Connect cable shields at the control end of your machine. Connect the motor cable shield to
GND, and connect the encoder shield to COM on the control.
• Do not connect the logic common (COM) of the IDC control to earth ground on your machine
or to the GND terminal on the control/drive. Separating earth ground from logic common min-
imizes the potential for ground loops.
• Use shielded cables inside your panel (if control is panel or cabinet-mounted) for I/O and
encoder wiring.
• Use differential, line-driven encoders with shielded, twisted-pair encoder cables. Single-ended
TTL encoders are susceptible to noise and should be avoided.
• For optimum noise immunity use IDC motors and encoders with IDC controls.

Additional Wiring Practices When Connecting an IDC Control to a PLC

• Connect the PLC logic common and the IDC COM terminals together.
• Disconnect the jumper between Pull-Up (or P-Up) and +12 VDC on the IDC control. Connect
the positive terminal of the PLC power supply to Pull-Up (or P-Up), and connect the Power
Supply common to the COM terminal on the IDC control, or to the PLC logic common (these
should both be at the same potential).
•IDC inputs are Sourcing, so PLC outputs connected to IDC inputs should be Sinking.
•IDC outputs are Sinking, so PLC inputs connected to IDC ouputs should be Sourcing.
Possible Ground Loop
Insert an ungrounded adapter to
break the ground loop. Do Not
Connect
Pig-tail
Wire
Preventing a Ground Loop