SERIAL PORTS SECTION 4
Page 4-2 RPC-320
Figure 4-2 Network diagram
400 LINEB 5,0,(LINEB(5,0) .AND. 251)
500 LINEB 5,0,(LINEB(5,0) .OR. 4)
Jumper W4 determines if COM1 receive is RS-232 or
RS-422/485.
W4[1-2] RS-485
W4[2-3] RS-232 (default)
COM1 default is RS-232. Use the CONFIG BAUD
statement to set the software to RS-422 or RS-485.
When set to RS-422, the transmitter is always on. RS-
485 mode turns on the transmitter only when sending.
RS-422/485 OPERATING INFORMATION
RS-422/485 Termination network
When the RPC-320 is the last physical unit on a network
(RS-485), or it is the only unit (RS-422), the receiver
must be terminated to prevent ringing. Jumper block
W5, 6 installs or removes this network. Insert a jumper
in W5 and W6 to install the network terminator.
Only one slave device on a RS-485 network should have
a terminator installed. The host transmitter should also
have a 100 ohm resistor in series with a 0.1 mfd
capacitor. The term inator on the RPC-320 includes pull
up and pull down resistors to prevent lines from floating
and generating erroneous char acters.
