Modbus RTU Energy Meter
The METZ CONNECT MR-(F-)SM4i and MR-(F-)SM4u energy meters enable the precise measurement of energy data for up to 3 phases plus neutral (L1, L2, L3, N) using transformers.
Data is transmitted via the standardized Modbus RTU protocol. When used in conjunction with the METZ CONNECT Modbus RTU Gateway MR-(F-)GW or the METZ CONNECT EWIO2-M(-BM) data loggers, the recorded measurement data is seamlessly integrated into IP-based network infrastructures. Alternatively, data transmission is also possible via Modbus gateways from third-party manufacturers. The advantage of the METZ CONNECT system solution lies in the pre-integrated templates for convenient commissioning and operation of the energy meters.
The meters measure current, voltage, active power, reactive power, apparent power, and other relevant energy parameters.
The compact DIN-rail modules offer Class B measurement accuracy and can be integrated into existing systems without tools thanks to the proven METZ CONNECT bridge connector
technology.
Customized solutions: Two variants, endless flexibility
Both meters are available with either screw terminals or springloaded terminals (push-in technology). The spring-loaded terminal version allows for quick, tool-free wiring and significantly
reduces installation time.
MR-SM4u / MR-F-SM4u: Designed for current transformers with a 333 mV voltage output and Rogowski coils with a 50 mV output signal
Features
Application Example
The Challenge
In Germany and Europe, numerous companies are legally required to systematically track and optimize their energy consumption. In addition, some consumers rely on professionalenergy management even without legal requirements—to reduce energy costs, identify savings potential, and actively contribute to climate protection. Precise energy measurement
is the foundation for legally compliant documentation and successful optimization.
The Solution
This is where the system solution from METZ CONNECT comes into play. With a smart combination of the NG4 power supply unit, the web-based EWIO2-M data logger, and the
MR-(F-)SM4x energy meter with current transformers, energy data can be recorded with precision. The stored energy data can be analyzed and visualized directly using the EWIO2-M(-BM)’s integrated Node-RED. Integration into higher-level systems is achieved either via
Modbus TCP using the Modbus gateway or via Modbus RTU with third-party systems.
The Scenario
A manufacturing company operates multiple machines and production lines. To meet legal requirements, make energy costs transparent, and identify potential savings (e.g., energy
management according to ISO 50001 or energy audits according to DIN EN 16247), an intelligent energy measurement system is required.
- Compatible with MR-(F-)GW, EWIO2-M(-BM), and third-party systems via Modbus RTU
- Measurement accuracy according to Class B
- Seamless energy data acquisition from machines and systems through to central evaluation
- Flexible thanks to various transformer types and current ranges
- Retrofittable without downtime thanks to Rogowski coils
- Measurement of up to 3 phases plus neutral conductor
- Recording of current, voltage, active power, reactive power, apparent power, and other relevant energy parameters
System Overview
Energy meters can be accessed via the IP network using the integrated web server of the MR-(F-)GW Modbus gateways and the EWIO2-M(-BM) data logger.
The energy meters are conveniently configured via a user-friendly web interface. Preconfigured templates for the energy meters in the MR-(F-)GW and EWIO2-M(-BM) enable quick and easy commissioning.
When integrating into third-party Modbus systems, configuration is performed directly via standardized Modbus registers.
Integrated Node-RED environment
The EWIO2-M(-BM) data logger features an integrated Node-RED environment. Node-RED is a graphical development environment that allows the collected energy data to be processed, analyzed, and visualized directly – simply via drag-and-drop in a web browser.
The energy measurement values from the connected energy meters are available in Node-RED. For example, you can detect load peaks, calculate energy costs, or perform efficiency analyses. If power limits are exceeded, email notifications can be sent automatically. Custom energy dashboards with real-time displays, consumption charts, and historical evaluations can be created.
The flow example demonstrates energy monitoring: Measurement values are retrieved, checked against power limits, and an alarm is sent if limits are exceeded; simultaneously, the data is visualized in the dashboard.
The energy dashboard displays all key metrics: current power, energy consumption, and historical trends.
Ordering Information
Brochure