Rockwell Automation 2706 DL20 SERIES G USER MANUAL - Manual (Page 120)

Chapter 9
Installation and Maintenance
9–9
Data at the RS-422 port is interpreted identically to data input on the RS-232
port. The chief advantage of using the RS-422 port is that it has better output
characteristics and transmits data in a way that is inherently more
noise-immune than RS-232. This enables RS-422 links to be up to 4000 feet
long (3/4 miles). Use the RS-422 to connect one or more DL20s to a host
controller or to one or more DL10 slave displays.
Connecting DL10 Slaves
Connect DL10 slave displays to either the RS-232 or RS-422 port. Up to 32
DL10 slaves can be connected to the RS-422 output port at a maximum
distance of 4,000 feet without the use of in-line amplification. Using in-line
RS-422 amplification up to 100 separately addressable slave DL10s can be
connected to the RS-422 output of the DL20 out to a maximum distance of
4,000 feet (1219 meters).
Connect the slaves to the RS-422 output of the DL20 using a 100% shielded
twisted pair cable with drain wire. Slave address and baud rates are selected
by a DIP switch on the DL10. The DL10 baud rate must match that of the
DL20.
Figure 9.9
Connecting DL10 Slaves
RS-422 IN +
RS-422 IN -
RS-422 +
RS-422 -
RS-422 IN +
RS-422 IN -
H
O
S
T
5
4
4,000 Feet (1,219 Meters) Maximum
GND 8
PLC DL20 Master DL10 Slave DL10 Slave
Serial or Parallel
Connection to Host
Note: It’s possible to use RS-232 output to one slave, however the distance
limitation is 50 feet.
Connecting RS-422 Devices