41-621.1 HART
®
to Modbus
®
Adaptor Operating Manual
29
10.
Modbus RTU Communication in Single Modbus Device Mode
10.1.
Purpose
This procedure instructs how to configure the HART to Modbus Adaptor (HMA), when in the Single
Modbus Device mode, to support the various parameter registers defined for the attached device.
In the Single Modbus Device mode (register 3012 set to 2), the HMA and attached HART device will
appear to be a single native Modbus device to the Modbus RTU/master. This mode is for instances
where an HMA is used with a single HART device and is designed to simplify the commissioning
process. When the HART poll address of the device is changed, the HMA will automatically change its
Modbus address to match the HART address when it starts up. Note that the range of Modbus/HART
addresses is limited to 1 through 62.
10.2.
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
Power Supply
-
20-24V, 0.5A
Level transmitter
MII
Model 706
Probe
MII
Model 706 compatible
10.3.
Setup
Connect the HMA (mounted in a housing with a HART device) 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.
10.4.
Procedure
10.4.1
Using Procedure 1 (with position 1 of the DIP switch set to OFF), configure the
communication settings HMA to match the settings for the Modbus host.
10.4.2
Using Procedure 2 (with position 1 of the DIP switch set to OFF), verify that register 3012
on the HMA is set to a value of 2
–
Single Device.
10.4.3
Using the device’s local display, change the HART Poll Address to t
he desired Modbus
address (within the range of 1 to 62). On 4-button, multi-line displays, the Poll Address
parameter can be found by navigating to the Device Setup\Advanced Config\Analog
Output menu. On 3-button, 2-line displays, the Poll Address parameter can be found by
repeatedly pressing the Up or Down arrow button.
10.4.4
Set position 1 of the DIP switch to ON.
10.4.5
The HMA will search through the 1 to 62 poll range for the attached HART device. Once
the device is found, the HMA will automatically change its Modbus address to match, and
then restart itself to use the new Modbus address.
Содержание Jupiter JM4
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