The Interface Solution Experts
25
HIM
Smart HART
Loop
Interface and Monitor
Figure 19.
Installing a HIM with MODBUS output into the loop using the Transmitter Excitation (+TX) terminal
READY
INPUT
60.278
TRIP 2
TRIP 1
COM
DEG C
0
ADDR
COMMON
NC (normally closed)
NO (normally open)
4-20mA
DCS
Sensor
Input
NO
NC
–
+
24Vdc
Power
Source
R must be
>
250 ohms and
<
1100 ohms
R
HART
Field Instrument
(Temperature,
Pressure,
Level,
Flow Multivariable)
HART Communicator
can be connected
anywhere on the loop
COM
+IN
+TX
–IN
MODBUS output
(with MODBUS option)
A
B
S
RS485 / RS232
Converter
TO serial
(COM) port
of PC
MODBUS Host
(+) DC
GND
(-) DCC
MODBUS 0ffsets
(where applicable)
Table 3 contains (zero based) MODBUS addresses . Your MODBUS host may require you to enter the MODBUS
register. Often MODBUS registers have an offset of “1” from the MODBUS address. For example, a MODBUS ad-
dress listed below of 256 may have to be entered as 257 in your host. Please refer to your MODBUS host docu-
mentation for verification.
