Magnetrol Jupiter JM4, Operating Manual

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41-621.1 HART ® to Modbus ® Adaptor Operating Manual
14.
Auto Switching Between LevelMaster and HART over RS-485 Communication
14.1.
Purpose
This procedure instructs how to configure the HART to Modbus Adaptor (HMA) to automatically switch
between Modbus and HART over RS-485 communication when it receives the appropriate commands.
This procedure uses a Model 706 as the attached device as an example; other Magnetrol HART devices
can also be used with this procedure.
14.2.
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
PACTware PACTware Consortium Version 4.1 or higher
HART Modem MacTek Viator
Level transmitter MII Model 706
Probe MII Model 706 compatible
14.3.
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. Connect a Model 706 transmitter and probe,
or other supported Magnetrol HART transmitter, to the HART loop terminal block of the HMA. The
device’s Poll Address can be set to any value between 1 and 62.
14.4.
Procedure
14.4.1
Using Procedure 1, ensure that registers 3000 through 3007 of the HMA match the values
shown for the Modbus LevelMaster protocol default settings. The address shown in
register 3001 can be between 1 and 62. Refer to Appendix H for the HMA Communication
settings. If the settings do not match, double-click on a value that needs to be changed to
open the Write Single Register dialog, enter the new value, and then click on Send.
14.4.2
Change DIP switch 1 to ON.
14.4.3
Ensure that the Modbus Poll application is not communicating with the HMA.
14.4.4
Select Connection\Disconnect from the Modbus Poll menu bar.
14.4.5
Start the Terminal v1.9b application.
14.4.6
Set the COM Port to match the COM port used for the communication cable (the same
number as with the Modbus Poll application).