Woodward 2301E-ST, Installation And Operation Manual

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Manual 26694 2301E-ST
Woodward 27
Termination
For RS-422, termination should be located at the receiver when one or more transmitters are connected
to a single receiver. When a single transmitter is connected to one or more receiver, termination should
be at the receiver farthest from the transmitter. Figure 2-6 is an example.
Figure 2-6. RS-422 Terminator Locations
Grounding and Shielding
The RS-422 specifications state that a ground wire is needed if there is no other ground path between
units. The preferred method to do this is to include a separate wire in the cable that connects the circuit
grounds together. Connect the shield to earth ground at one point only. The alternate way is to connect all
circuit grounds to the shield, and then connect the shield to earth ground at one point only. If the latter
method is used, and there are non-isolated nodes on the party line, connect the shield to ground at a non-
isolated node, not at an isolated node. Figures 2-7 and 2-8 illustrate these cabling approaches.
Non-isolated nodes may not have a signal ground available. If signal
ground is not available, use the alternate wiring scheme in Figure 2-8
with the signal ground connection removed on those nodes only.
Figure 2-7. Preferred Multipoint Wiring Using Shielded Twisted-pair Cable
with a Separate Signal Ground Wire
Released