Type 2530H1
7
Figure 10. End View of HART Interchange Multiplexer
Showing RS485 Connector
, Power Connector, and Ground Stud
RS-485 CONNECTOR
GROUNDING
STUD
POWER CONNECTOR
W6488*/IL
Connecting Multiplexer Power
CAUTION
When applying power to the multiplexer,
do not exceed 36 volt dc. Exceeding 36
volt dc will blow the fuse. Although the
fuse automatically resets, constant ex-
posure to high voltages may damage
the unit.
The multiplexer requires 24 volt dc at 300 mA. Con-
nect the power supply using the 2-terminal removable
terminal block that is plugged into the multiplexer pow-
er connector. See figures 4 and 10 for the power con-
nector location. The power connector is polarized so
that it cannot be inserted incorrectly. The polarity of
the terminal block is marked on the multiplexer.
To connect the metalwork of the multiplexer to chassis
ground, use either of the studs provided on the unit.
See figure 10.
Note
The HART interchange multiplexer con-
tains a DC-to-DC converter so ground
loop problems will not occur.
No external power is required for the filters, they draw
their power from the 4 to 20 mA loop current.
Connecting Multiple HART Interchange
Multiplexers
Figure 11 shows the connection between multiplexers.
To connect multiple HART interchange multiplexers:
1. Connect the A and B terminals of each multiplexer
on the RS485 network to the A and B terminal of the
next unit (i.e., A to A and B to B).
2. Place a 100-ohm resistor between the A and B ter-
minals on the last multiplexer in the arrangement.
Note
The following step is optional.
3. Connect the shield of the RS485 twisted pair wire
to the 0V terminal on the multiplexer RS485 connector
to reduce interference with the RS485 line.
Connecting Multiplexers to the
RS232-to-RS485 Converter
CAUTION
Do not connect 24 volt dc power to the
RS485 connection. Power applied to the
RS485 connection can damage the
RS485 circuitry and cause HART inter-
change multiplexer failure.
The RS485 connector is a 3-pin removable terminal
block located just above the power connector. The
three RS485 connections are labeled as shown in fig-
ures 4 and 10.
Connect the first multiplexer to the RS232-to-RS485
converter. Refer to figure 11.
Note
The first HART interchange multiplexer
A and B terminals must be correctly
connected to the RS232-to-RS485 con-
verter to enable the host PC to commu-
nicate with all of the multiplexers on the
network.
1. Connect terminal A of the first multiplexer to termi-
nal G (DATA–) of the converter RS485 OUT connec-
tor.
2. Connect terminal B of the first multiplexer to termi-
nal Y (DATA+) of the converter RS485 OUT connec-
tor.
Converter DIP Switches
Both the RS232-to-RS485 Converter and the HART
interchange multiplexer have user selectable DIP
switches. As shown in figure 12, the converter has
three sets of switches on the back panel.
The set of three switches adjacent to the RS485
IN connector determine the termination and biasing of
