Magnetrol Jupiter JM4, Operating Manual

Page: 31 / 124

41-621.1 HART ® to Modbus ® Adaptor Operating Manual
31
11.
Basic LevelMaster Communication
11.1.
Purpose
This procedure instructs how to configure the HART to Modbus Adaptor (HMA) to support the Modbus
LevelMaster protocol.
In the LevelMaster configuration, 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. The devices will return the HART PV and SV as the two D (float) values in the
Uxx? command response. The F value corresponds to the Echo Signal strength. The E and W values
correspond to the highest active Error and Warning diagnostic in each category.
11.2.
Equipment
Item Manufacturer Model
HART to Modbus Adaptor MII 031-2859-001
RS485 Communications cable FDTIchip USB-RS485-WE
Termination resistor - 120

Modbus host application www.modbustools.com Modbus Poll
Terminal v1.9b application hw-server.com Version 1.9b - 20040204
Power Supply - 20-24V, 0.5A
Level transmitter MII Model 706
Probe MII Model 706 compatible
11.3.
Setup
Connect the HMA to a power supply via the power terminal block. Connect an RS-485 communications
cable to the RS-485 terminal block of the HMA, with the Receive/Transmit Data+ A lead (orange) on
the positive terminal and the Receive/Transmit Data
– B lead (yellow) on the negative terminal.
Connect a 120

resistor between the two RS-485 terminal block positions. Connect the other end of
the cable to a PC which has a Modbus host application. Besides the Model 706 in the housing, connect
any additional HART devices to the HART loop terminal block of the HMA. Set the HART Poll Address of
the internal Model 706 device to 2. Set the HART Poll Address of the other attached devices to
different, unique values. Note that other Magnetrol HART transmitters and HART poll addresses can
be used.