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Main modwrt.png

A new version of the MODWRT is under development. See more here MODWRT2.

Modbus RTU to Emoncms Influxdb Thingspeak

Modbus to Emoncms. The ModWRT is a Modbus RTU unit to interface with one or several RS485 RTU devices. The ModWRT sends a predefined set of registers value to a server for data logging and display.
The end server can be either of type Emoncms, Influxdb or Thingspeak.

All communication and dataflow parameters are configured using a web interface.

Technical Specifications

  • RS485 port
  • Ethernet port
  • Integrated Wifi
  • Micro-usb Power supply
  • Operating system: OpenWRT 14.07
  • Flash Memory: 64MB
  • Dimensions: 90x60x30mm
  • Enclosure: Aluminium case
  • Optional Wifi antenna


The ModWRT web interface is build within the OpenWRT web interface.

There are three main functional area which are:
1/ RTU's definitions
2/ Servers definitions
3/ Dataflow configuration (ie which data goes where).

The web interface is briefly described below. See more details in the user manual.

1. RTU definition

All Modbus RTU devices can be configured on one single page using Slave ID and communication parameters (baud rate etc).

Web 001.png

2. Stream to Emoncms, Influxdb, Thingspeak definition

Internet of Thing (iot) servers can be configured on this page.

Modwrt streams 01.png

3. Dataflow Configuration

This page will configure all dataflow combination.

A single dataflow can query different RTU unit to send combined data onto a single export.

Modwrt dtfl 01.png

As an example the above example will display the following data on Emoncms.

Web 004.png

User Manual

Modwrt First use

Modwrt Web Interface

Modwrt on Command Line

Emonwrt3 Network Configuration (same applies for EMonwrt3 and Modwrt).

Modwrt Update New Software

Related Articles

Use PZEM-016 with MODWRT