Rockwell Automation 1746-XXXX SLC 500 4-Channel Analog I/O Modules User Manual - Manual (Page 31)

Publication 1746-UM005B-EN-P - June 2004
Installing and Wiring Your Analog Module 3-9
System Wiring Guidelines
Use the following guidelines in planning the system wiring for the
analog modules:
•
all analog common terminals (ANL COM) are electrically
connected inside the module. ANL COM is not connected to
earth ground inside the module.
•
voltages on IN+ and IN- terminals must remain within ± 20 Volts
with respect to ANL COM to ensure proper input channel
operation. This is true for current and voltage input channel
operation.
•
voltage outputs (OUT 0 and OUT 1) of the NIO4V and NO4V
are referenced to ANL COM. Load resistance (R1) for a voltage
output channel must be equal to or greater than 1K ohms.
•
current output channels (OUT 0 and OUT 1) of the NIO4I and
NO4I source current that returns to ANL COM. Load resistance
(R1) for a current output channel must remain between 0 and
500 ohms.
Grounding Your Cable
Belden cable #8761 has two signal wires (black and clear), one drain
wire and a foil shield. Refer to the illustration on p. 3-10. The drain
wire and foil shield must be grounded at one end of the cable. Do not
earth ground the drain wire and foil shield at both ends of the cable.
Input Channel - Use a chassis mounting tab as a ground for the drain
wire and foil shield.
Output Channel - Ground the drain wire and foil shield at the analog
load.
IMPORTANT
If you cannot ground the output channel at the load,
ground the drain wire and foil shield at the chassis
mounting tab. Do not connect the foil shield or drain
wire to the analog terminal block. They must be
connected to an earth ground, which is not provided
at the analog module.