9
HS RS-232
↔
60 MA CURRENT LOOP CONVERTER
4. Installation
The Converter is simple to install. After configuring the DTE/DCE switch,
connect the two twisted pairs using one of three methods: terminal blocks
with strain relief, RJ-11 jack, or RJ-45 jack. The method you use will depend
on the specific model you have.
4.1 Twisted-Pair Wiring Overview
Only one Converter is needed for each RS-232 to 60-mA current-loop circuit.
The Converter is connected to the current-loop device using two twisted pairs.
The pairs must be “dry” (unconditioned) metallic wire, 19 to 26 AWG. Best
distance is achieved with larger gauges. When you have completed wiring for
your data circuit, the pin connections should be as shown below:
XMT+ -------------------------------------------------------------------RCV+
XMT- --------------------------------------------------------------------RCV-
G -----------------------To Shield (Optional)------------- G
RCV+ --------------------------------------------------------------------XMT+
RCV - ---------------------------------------------------------------------XMT -
4.1.1 T
WISTED
-P
AIR
C
ONNECTION
U
SING
T
ERMINAL
B
LOCKS
The terminal-block/strain-relief version of the Converter allows you to hook
up the line-side interface using bare wires. The following instructions will tell
you how to open the case, connect the bare wires, and fasten the strain-relief
collar in place.
1. Open the unit by gently inserting a screwdriver between the DB25
connector and the lip of the plastic case (see
Figure 4-2
). You don’t have
to worry about breaking the plastic, but be careful not to bend the D-sub
connector.
