Rockwell Automation 1758-RTU202 DataSite Hardware User Manual - Manual (Page 41)

Publication 1758-UM001D-EN-P - June 2011
Wiring the Controller 41
Termination Resistors
120-ohm termination resistors are required on each of the two physical ends of
one network segment. It also means that the two communication ports which
are on the physical end position of one network segment must be connected
with termination resistors. Other communication ports of this network
segment should not be connected with termination resistors.
See RS485 Field Wiring—Two-wire Mode on page 40 .
These termination resistors are installed to make sure the data received will be
accurate even if the following conditions on the RX line occur:
• Open inputs
• Terminated inputs
• Sudden inputs (shorted circuit)
Wiring for HART Communication
The controller comes with three HART protocol communications ports,
including one that is multi-point, and can connect to 13 HART protocol
meters. The other two are point-to-point ports, and can also collect 4…20 mA
signals.
HART multi-point port wiring
HO+
DC Power
Supply
HO-
Two Wire
Slave #13 Two Wire
Slave #2
Two Wire
Slave #1
31 30
44701