Modbus

Modbus is a communication protocol, designed by Modicon for use with its programmable logic controllers (PLC)s. It is almost a de facto standard communications protocol in industry since it represents the most commonly available means of connecting almost any industrial electronic devices, which permits great savings in wiring costs. A lot of the reason for the extensive use of Modbus instead of other communications buses is the fact that it is openly published. It allows for administration of a net of devices, for instance a system that records temperature and humidity and stores results in a computer. Versions for serial port and ethernet were created.

External links:

• protocol description (http://www.modicon.com/techpubs/toc7.html)
• Modbus-IDA site (http://www.modbus.org)
• Schneider Automation site (http://www.modicon.com/Default.htm)

Free software exists for modbus:

• search freshmeat (http://freshmeat.net/search/?q=modbus&section=projects&Go.x=0&Go.y=0)
• search sourceforge (http://sourceforge.net/search/?words=modbus)

pl:modbus