Remote Technologies RPC-320 - Manual (Page 16)

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 W 4 determines if COM 1 receive is RS-232 or
RS-422/485.
W4[1-2] RS-485
W4[2-3] RS-232 (de fault)
C O M 1 d ef a ul t i s R S -2 3 2. U s e th e C O NF I G BA U D
statement to set the software to RS-422 or RS-485.
When set to RS-422, the transm itter 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 shou ld also
have a 100 ohm resistor in series with a 0.1 m fd
capacitor . T he term inator on the RPC -320 includes p ull
up and pull down resistors to prevent lines from floating
and generating er roneous char acters.