RS485 Positive Displacement Flowmeter

Overview

Accurate liquid flow measurement is important for production control and energy management in modern industrial automation systems. RS485 positive displacement flow meter (or we call PD flow meter), as an advanced liquid measurement instrument that integrates high-precision measurement, intelligent data processing, and remote communication transfer, is becoming the preferred measurement equipment in industries such as petrochemicals, food and pharmaceuticals, and water treatment. This article will delve into the technical characteristics, communication protocols, and practical applications of this RS485 Modbus flowmeter.

Digital RS485 Positive Displacement flow meter with Electronic Display

The core of RS485 PD flow meters is advanced digital flow counters. This series of digital PD flow meter adopts advanced technology design, with high reliability characteristics, and can be combined with various positive displacement flow sensors (such as oval gear flow meter, roots flow meter or helical gear flow meter), to form a complete digital volumetric flow measurement system. Users can directly read total and instantaneous flow data on the flowmeter.

Display and measurement capabilities

The BELZ series digital display adopts a dual row LED display screen with a wide display range: the single cumulative amount ranges from 0.000 liters to 99999999 liters, and the total cumulative amount can reach 99999999999 liters. The instantaneous flow display range is from 0.000 to 999999 liters/hour. This large-scale measurement capability enables it to adapt to various industrial application scenarios ranging from small to large flow rates.

Why we prefer to use RS485 Positive Displacement Flowmeter ?

• The RS485 communication protocol is one of the most mature and reliable communication standards in the field of industrial automation,silverinstruments.com use MODBUS RTU. Compared to traditional 4-20mA analog flow meter, RS485 has the following significant advantages:
• Digital transmission: RS485 uses digital signal transmission to avoid the problems of analog current signal interference and accuracy loss. When transmitting over long distances (up to 1200 meters), the signal quality is stable and reliable, while for 4-20mA transmitter, maybe 50meters is long enough .
• Multi device networking: One RS485 bus can connect up to 255 devices (such as flow meter, pressure transmitter, level transmitter and so on), greatly reducing wiring costs and system complexity. In large factories, it is easy to build a traffic monitoring network.
• Bidirectional communication: MODBUS RS485 not only can it read traffic data, but it can also perform parameter settings and device status queries, achieving true intelligent management.

Implementation of MODBUS RTU Protocol

The RS485 PD flowmeter adopts the standard MODBUS RTU protocol, with communication parameters including baud rate of 9600 bps, 8-bit data bits, no checksum (configurable), and 1-bit stop bit. The device address range is 1-255, which can be set through menu F08.
The protocol supports function code 0x03 (read hold register), which can read 7 sets of key data:

Total cumulative traffic (high 6 digits, low 6 digits, decimal 6 digits)
instantaneous flow rate
Single cumulative traffic (4 digits high, 6 digits low, 6 decimal places)

For example, when reading the current display value of the device with address 01, the host sends: 01 03 00 01 00 08 15 CC, and the slave returns 16 bytes of data containing complete traffic information.Clik here for more setting :RS485 MODBUS RTU PD flow meter setting

Technical specifications of MODBUS Digital Positive Displacement Flowmeter

Explosion proof and protective performance
This series of products has excellent environmental adaptability:
Explosion proof rating: Exd II BT5/Exd II CT5, suitable for use in flammable and explosive environments
Protection level: IP65, dustproof and waterproof
Working temperature: -25 ° C to+55 ° C, suitable for harsh working conditions

Intelligent functions

• The flowmeter is equipped with multiple intelligent functions:
• Damping coefficient adjustment (F03 menu): effectively eliminates instantaneous flow fluctuations, can be set to levels 1-99
• Multi point linearization (F61-F65): improves full range accuracy through segmented coefficient correction
• Current output calibration (F05/F06): Fine adjustment of 4mA and 20mA to ensure output accuracy
• Communication parameter configuration: supports three modes: no verification, odd verification, and even verification

Application value for RS485 Positive Displacement Flowmeter

In practical industrial applications, RS485 volumetric flow meters demonstrate unique advantages:
Centralized monitoring: Through RS485 networking, real-time flow data from multiple measurement points can be monitored in the central control room without the need for on-site meter reading.
Data traceability: Digital data is easy to store and analyze, and the total cumulative amount cannot be reset to ensure measurement fairness.
Reduce maintenance costs: Remote diagnosis and parameter adjustment functions reduce on-site maintenance workload.

Conclusion

The RS485 PD flowmeter represents the development direction of flow measurement technology, which perfectly combines precise mechanical measurement with advanced digital communication technology. With the advancement of Industry 4.0 and intelligent manufacturing, this networked and intelligent measuring instrument will undoubtedly have a wider range of applications. Choosing the appropriate RS485 flowmeter is not only about choosing a measuring device, but also laying the foundation for the digital transformation of the enterprise.