Watlow CAS200 - Manual (Page 39)

CAS200 User’s Guide Chapter 2: Installation
Watlow Anafaze 27
Figure 2.14 EIA/TIA-485 Wiring
Cable Recommendations
Watlow Anafaze recommends Belden 9843 cable or its
equivalent. This cable includes three 24 AWG (0.2 mm 2 ),
shielded twisted pairs. It should carry signals of up to
19200 baud with acceptable losses for up to 4000 feet (1220
m).
EIA/TIA-485 Network Connections
Watlow Anafaze recommends that you use a single daisy
chain configuration rather than spurs. Run a twisted-pair
cable from the host or converter to the first CAS200, and
from that point run a second cable to the next CAS200, and
so on. See Figure 2.15.
If necessary for servicing, instead of connecting each
scanner directly to the next, install a terminal strip or
connector as close as possible to each CAS200, run a
communications cable from one terminal strip to the next
and connect the scanners to the bus with short lengths of
cable.
To avoid unacceptable interference, use less than 10 feet (3
m) of cable from the terminal or connector to the CAS200
serial port.
Some systems may experience problems with sensor signal
readings if the commons of multiple scanners are
connected. See Signal Common on page 28 for more
information.
Refer to Termination on page 28 for more on terminating
resistors.
Connect the shield drain to earth ground only at the
computer or host end.
232-to-485 Converter
TXA/TDA/TX-
TXB/TDB/TX+
RXA/RDA/RX-
RXB/RDB/RX+
RXA 25
RXB 23
TXA 26
TXB 24
RXA 25
RXB 23
TXA 26
TXB 24
Do not
A
B
A
B
connect
shield to
CAS200
First CAS200 Last CAS200
JU1 JU1
Personal
Computer