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Together with an industrial RS232-to-RS485 converter (Westermo MDW-45). There are direct USB-to-RS485 converters, but I use a USB-to-RS232 converter To connect your computer to the RS485 bus, a serial port is required. The serial bus RS485, which is described at. Only the master can initiate communication. There can be several instruments (slaves, nodes) on a single bus,Īnd the slaves have addresses in the range 1 to 247. Also a driver for Omega CN7500 is included.įor hardware details on these process controllers, see It uses the MinimalModbus Python moduleįor its communication. (using a serial link), so there should be lots of applications.Īs an example on the usage of MinimialModbus, the driver I use for anĮurotherm 3504 process controller is included. MinimalModbus is intended for general communication using the Modbus RTU protocol These come with different types of communication protocols,īut the controllers I prefer use the Modbus RTU protocol. The application for which I wrote this software is to read and write data

Note that the computer (master) actually is a client, and the instruments (slaves) are servers. Modbus over serial line specification and implementation guide V1.02

Not supported by this software, consider donating some Modbus TCP equipment.įor full documentation on the Modbus protocol, see Two important documents are: Modbus TCP, and variantsĪ protocol for communication over TCP/IP networks. Modbus ASCIIĪ serial protocol that uses ASCII representation of the data. There are several types of Modbus protocols: Modbus RTUĪ serial protocol that uses binary representation of the data. It is often used to communicate with industrial electronic devices. Modbus is a serial communications protocol published by Modicon in 1979, The download section is at the end of the page. Python package index (PyPI) with download Home page Home page with full API documentation It is open source, and has the Apache License, Version 2.0. This software supports the ‘Modbus RTU’ and ‘Modbus ASCII’ serial communication versions of the protocol,Īnd is intended for use on Linux, OS X and Windows platforms. The only dependence is the pySerial module (also pure Python). MinimalModbus is an easy-to-use Python module for talking to instruments (slaves)įrom a computer (master) using the Modbus protocol, and is intended to be running on the master.Įxample code includes drivers for Eurotherm and Omega process controllers. INA226 High-Side or Low-Side Measurement, Bi-Directional Current and Power Monitor with I2C Compatible Interface (datasheet). ADS1100: Self-Calibrating, 16-Bit Analog-to-Digital Converter (datasheet). Texas Instruments (formally Burr-Brown) (2003). Two-wire bus-system comprising a clock wire and a data wire for interconnecting a number of stations. Reading a VGA monitor’s configuration data with I2C and a PocketBeagle.