6
41-621.1 HART
®
to Modbus
®
Adaptor Operating Manual
Operating Modes
Modbus RTU and Modbus ASCII
When using the Modbus RTU and ASCII protocols, the HMA can be used in several ways:
1.
HMA with a single transmitter (HMA mode)
–
The Modbus host addresses the HMA directly,
using the address of the HMA. The registers in the HMA for the attached device follow the
numbers listed for Slave 1 in the device register appendices L through S. In this mode, the
allowable Modbus addresses are in the range of 1 through 247.
This is the default
configuration for the HMA.
2.
HMA with multiple transmitters and one Modbus address (HMA mode)
–
The Modbus host
addresses the HMA directly, using only the address of the HMA. The registers in the HMA for
each attached device depend on the slave number of the attached devices as listed in
Appendices L through S. The HMA will appear to be a Modbus device capable of providing
multiple level measurements. In this mode, the allowable Modbus addresses are in the range
of 1 through 247.
3.
HMA with multiple transmitters and multiple Modbus addresses (Device mode)
–
The Modbus
host addresses the HART devices directly, using the HART Poll Address of each device as the
Modbus address. (The HMA is essentially transparent.) The HART devices will appear to be
native Modbus devices to the Modbus host. The registers for each attached device type are the
same regardless of the poll address. The registers in the HMA for each attached device follow
the numbers listed for Slave 1 in the device register appendices L through S. In this mode, the
allowable Modbus/HART addresses are limited to the range of 1 through 62.
4.
Single Modbus Device
–
The HMA is connected to only the HART device present in the same
transmitter housing. The HART poll address of the HART device and the Modbus poll address of
the HMA are the same. Changing the HART poll address of the attached transmitter will
automatically change the Modbus poll address of the HMA to match. Essentially, they appear
to a Modbus master as a single native Modbus device. The registers in the HMA for the
attached device follow the numbers listed for Slave 1 in the device register appendices L
through S. In this mode, the allowable Modbus/HART addresses are limited to the range of 1
through 62.
LevelMaster
When using the
LevelMaster
protocol, the HMA will appear to be invisible to the LevelMaster host.
This is due to the limited command set available with LevelMaster. Instead, the attached HART devices
will appear to be native LevelMaster devices. They will respond to the Modbus poll address equivalent
to their HART poll address. In this mode, the allowable Modbus/HART addresses are limited to the
range of 1 through 62.
Summary of Contents for Jupiter JM4
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