Manual 85586V1
AtlasPC Digital Control, Vol. I
Woodward
37
Figure 5-20. Wiring Example–Alternate Multipoint Wiring
(without a separate signal ground wire for the SmartCore board)
Configuration Notes
•
Refer to Figure 5-17 for RS-232 wiring. The transmit data (TXD), receive
data (RXD), and signal ground (SIG GND) must be properly connected as
shown. In addition the shield (SHLD) should be connected in at least one
location.
•
Refer to Figure 5-18 for RS-422 wiring. The transmit data pairs (422T+ and
422T-), receive data pairs (422R+ and 422R-), and signal ground (SIG
GND) must be properly connected as shown. In addition, the shield (SHLD)
should be connected in at least one location. The last unit in the network
chain, and only the last unit, should have it’s receiver terminated with a
resistor. The AtlasPC has resistors built in (TERM RES) for this purpose.
This applies to both ends of the network.
•
Refer to Figure 5-19 for RS-485 wiring. The data lines (485+ and 485–) and
signal ground (SIG GND) must be properly connected as shown. In addition,
the shield (SHLD) should be connected in at least one location. The last unit
in the chain, and only the last unit, should be terminated with a resistor. The
AtlasPC has resistors built in (TERM RES) for this purpose. This applies to
both ends of the network.
•
The serial ports must be properly configured in the application software for
the appropriate communication parameters.
•
Termination resistors are available on the SmartCore board and should be
wired across the network at the ends of the line.
•
The serial ports are individually isolated from each other, and from the rest
of the AtlasPC control. The RS-422 and RS-485 specifications state that a
ground wire is needed if there is no other ground path between units. The
preferred method for isolated ports is to include a separate wire in the
ground cable that connects the circuit grounds together.
•
Non-isolated nodes may not have a signal ground available. If signal ground
is not available, use the alternate wiring scheme of connecting all circuit
grounds of isolated nodes to the shield, and connecting the shield to earth
ground at a non-isolated node.
Summary of Contents for AtlasPC
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