Control Microsystems SCADAPack 32 - RS-485 Wiring Examples

• Install a jumper across J7 to terminate the Tx pair.
To disconnect the termination resistors:
• Remove the jumper across J8 to terminate the Rx pair.
• Remove the jumper across J7 to terminate the Tx pair.
9.6.4 RS-485 Wiring Examples
9.6.4.1 Four wire mode
Four-wire operation uses one pair of wires for transmitting data and a second pair for receiving data.
The transmitting pair is connected to the terminals marked +TX and –TX on the termination block.
The receiving pair is connected to the terminals marked +RX and –RX. See the figure below for an
illustrative example.
+TX
–TX
–RX
+RX
+TX
–TX
–RX
+RX
+TX
–TX
–RX
+RX
+TX
–TX
–RX
+RX
M AST ER
SLA VE
SLA VE
SLA VE
Last station in network
requires terminations.
First station in network
requires terminations.
RS-485 network
4000 feet (1200 m)
maximum length
SCADAPack 32 Controller Hardware Manual
May 24, 2006
33