Application scenarios of converting HART to MODBUS protocol
In industrial settings, flow meters serve as essential instruments for measuring fluid flow. With industrial advancements and the growing demand for smart manufacturing in factories, market requirements for communication capabilities in flow meters have been increasing steadily, necessitating higher precision in data collection. Traditional manual meter reading in water treatment plants has evolved into automated meter reading, which has now progressed to highly accurate automated meter reading systems.
Traditionally, we used two methods to read the cumulative flow of flow meters:
-by counting pulses from the meter itself, for example, accumulating one cubic meter;
-by dividing instantaneous flow by 3600 seconds to obtain the cumulative instantaneous value per second.
Over time, both methods may develop issues like pulse leakage and inaccurate calculations. Prolonged operation will cause errors to accumulate, leading to a growing discrepancy between the upper computer's cumulative flow data and the flow meter's display. This makes instrument communication particularly crucial.
Instrument communication enables real-time transmission of flow data, diagnostic information, and status monitoring to the host computer control system, facilitating information exchange and enhancing factory automation. Once established, the data is real-time. The most commonly used communication protocols for flow meters are HART and Modbus 485.
The following will introduce the main communication of flowmeter in practical application.
I.Cologne IFC110 Flowmeter
As a legacy model, the Cologne IFC110 requires custom converter commands based on the communication protocol to convert measured data into standard MODBUS protocol output.
II.E+H Proline 400 Flowmeter:
Most E+H flowmeters support the HART protocol. Our company's HART protocol conversion module also natively supports multiple instrument protocols, making conversions highly convenient.
First, configure the module to operate in transparent mode. Then, use the configuration software to retrieve the flowmeter parameters and verify communication compatibility. If the parameters are successfully retrieved, switch the module to MODBUS mode to enable PLC-based flowmeter data reading.
Finally, using modscan software or the modbus-poll tool, we can now directly read both instantaneous and cumulative flow rates.
III.Siemens MAG5000 and MAG6000 flowmeters
1、MAG5000 read and write mode
First, the MAG5000 incorporates a built-in HART module. As specified in the manual, terminals 31 and 91 are shorted together, and terminals 32 and 92 are also shorted, as shown in the figure below:
2、MAG6000 read and write mode
The MAG6000 and MAG5000 share nearly identical designs, distinguishable by their serial numbers or nameplates, as shown in the figure below.
The above example lacks detailed operational instructions. In the future, industrial automation will increasingly integrate with the Internet of Things, such as communication with instruments, PLCs, and remote stations.