The Interface Solution Experts
21
HIM
Smart HART
Loop
Interface and Monitor
Appendix A: HIM MODBUS
Feature
The HIM PC program allows you to configure the
HART monitor. A HART Monitor with the MODBUS
option provides a digital MODBUS output to a con-
nected MODBUS-based controller. Selecting the
MODBUS tab allows you to set the MODSBUS com-
munications parameters. Notice that the
MODBUS tab
will only be available in units with the MODBUS option.
Figure A-1.
MODBUS Tab
Comms Settings
The Comms Settings include the following:
MODBUS Address
The
MODBUS Address is the number that the HIM
monitor uses to identify itself on the MODBUS net-
work. The MODBUS address is configurable from 1 to
247. By default, it will assume a MODBUS address of
01.
Baud Rate
The
Baud Rate is the speed of data transmission. It
should be set to match the baud rate of the attached
controller. The interface supports the following baud
rates: 300, 600, 1200, 2400, 4800, 9600 and 19200.
Parity
The HART monitor supports even, odd and no
Parity.
The data format is one start bit, 8 data bits and one
stop bit.
Floating Point Word Order
By default, the HART monitor will use the
Standard
LSW (least significant word) floating point word order
format. This stores the most significant bits in the
second register and the least significant bits in the first
register. Selecting
Swapped MSW (most significant
word) will reverse the order, storing the most signifi-
cant bits in the first register and the least significant
bits in the second register.
MODBUS Registers
The HART Monitor outputs a MODBUS signal to the
attached controller. To access the MODBUS registers
for variable, input/output or error information, refer to
Table A-1 (MODBUS Register Definitons table) and/or
Table A-2 (System Status Registers table).
