41-621.1 HART
®
to Modbus
®
Adaptor Operating Manual
5
INTRODUCTION
This document is intended to provide a guide for utilizing the various features of the Magnetrol HART
to Modbus Adaptor (HMA). For each feature, a step-by-step procedure is provided to demonstrate
how to set up the HMA and attached HART devices for a particular configuration. Other configurations
are possible with various combinations of the number of HART to Modbus Adapters on a single RS-485
line and the number and type of Magnetrol HART devices attached to those HMAs. The operations in
those configurations can be accomplished by extending the procedures provided in this document.
Additionally, it is not required to use the Modbus RTUs or host applications shown in this document.
Any RTU or host application that allows for reading and writing Modbus registers to a slave device can
be used.
The HART to Modbus Adaptor (HMA) is designed to allow Magnetrol HART transmitters to be utilized
in a Modbus®
1
system. The following Modbus protocols are supported:
•
Modbus RTU
–
Function codes 3, 4, 6, and 16
•
Modbus ASCII
–
Function codes 3, 4, 6, and 16
•
Levelmaster
–
Commands
Uxx?
,
UxxF?
,
UxxOL?
, and
UxxOLxxxx?
A unique feature of the HMA is that it will support up to five attached HART devices; one in the same
housing as the HMA, and up to four external devices attached through a 4-20 mA loop.
•
The attached devices do not have to all the same type transmitter.
•
The HMA provides power for all attached HART units.
•
The attached units should be set to a fixed 4 mA loop current.
Communication
Within the above protocols, it is possible to
configure communications parameters
such as baud rate,
parity, stop bits, etc. to match the settings for a particular Modbus Remote Terminal Unit (RTU) or
host.
To ensure a standard method to communicate with the HMA, setting DIP switch positions 1
–
3 to OFF,
and 4 to ON, (see Appendix A) will configure the HMA to communicate via Modbus RTU with the
default communications settings shown in Appendix F.
1
Modbus
®
is a registered trademark of Schneider Electric, licensed to the Modbus Organization, Inc.
Summary of Contents for Jupiter JM4
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