+ TX
–TX
–RX
+ RX
+ TX
–TX
–RX
+ RX
+ TX
–TX
–RX
+ RX
+ TX
–TX
–RX
+ RX
MASTER
SLAVE
SLAVE
SLAVE
Last station in network
may require terminations.
First station in network
may require termination.
RS-485 network
4000 feet (1200 m)
maximum length
4.5.2
Two wire mode
Two wire operation uses one pair of wires for transmitting and receiving data. +Tx must be
connected to +Rx and –Tx must be connected to the –Rx. This pair of wires becomes the
transmitting and receiving pair. The following diagram shows the wiring details for a two wire
connection.
SCADAPack 32P Controller Hardware Manual
May 26, 2006
23
