The jModbus Project


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What is it?

The jModbus project aims to provide Java libraries to allow java based devices to comminciate as either master or slave devices via ModbusRTU (Modbus), ModbusASCII (ModbusA) or ModbusTCP (Modnet). The code is open source and designed to run on devices with a small footprint, such as the Dallas Semiconductor TINI.

The class structure is OO by deisgn, hopefully allowing for extensions such as SEMI over ModbusTCP to be written easily.

For more information relating to Modbus and Modbus TCP please refer to Open Modbus and the Modicon Modbus site. The modbus protocol was orignally designed by Schneider Electric (makers of Modicon PLCs) for communication with Modicon PLCs.


This site shows a number of examples for the use of the jModbus code.
A sample of a Citect project using the jModbus code to communicate with a network of TINIs over ModbusTCP (Modnet) for taking temperature measurments using DS18S20 chips is shown here.


8-November-2001: Version 0.1.1 released. This new release has a working ASCII transport module and includes some bug fixes to the Master and Slave code relating to bit manipulation routines. This is likley to be the last release before the code from Dieter Wimberger is integrated.

10-October-2001: Dieter Wimberger from the Institute for Automation, University of Leoben, Austria has decided to open source a Modbus/TCP implementation he has written and we will begin to merge the coed base shortly.

16-September-2001: First release, version 0.1.0 released. Please download the full tar ball or just get the jar for library use.

10-August-2001: First versions of the code have now been uploaded into the CVS archive.

3-August-2001: jModbus web site goes live for the first time. Code to follow shortly.

This site is in no way connected to or endorsed by either Open Modbus, Modicon or Schneider Electric

Java is a trandmark of Sun Microsystems. This site is in no way connected to or endorsed by Sun Microsystems,

The style of this site has been stolen from the XML 1-Wire Tagging Project who I hope will not mind this incursion.