malequardos Posted December 1, 2016 Report Share Posted December 1, 2016 Does anybody know if Vision controllers (ie V130) support Modbus TCP or do they support the Modbus RTU over TCP implementation. The difference is that the first follows the original Modbus TCP frames (ie no CRC) while the latter encapsulates the serial RTU framing sent over TCP media. Which one is supported by Vision and the other Unitronics controllers? Quote Link to comment Share on other sites More sharing options...
Gabriel Franco Posted December 1, 2016 Report Share Posted December 1, 2016 Vision Enhanced such as V130 does support both Modbus TCP and Modbus RTU Quote Link to comment Share on other sites More sharing options...
Paul Rylatt Posted December 13, 2016 Report Share Posted December 13, 2016 Modbus RTU is not a TCP protocol. Modbus TCP/IP is designed for sending over an Ethernet network (Vision optional) while Modbus RTU is designed to be sent over a serial network such as RS-485 (Vision standard). It is common to confuse the data layer with the transport protocol. Modbus TCP/IP = data layer; Ethernet = transport protocol. Modbus RTU = data layer; RS-485 = transport protocol. Modbus TCP/IP can be simplified as Modbus RTU with additional information in the data packet for sending over an Ethernet network. Quote Link to comment Share on other sites More sharing options...
stembera Posted December 30, 2016 Report Share Posted December 30, 2016 I am afraid the answers above are still confusing. Malequardos asked if there is a support for Modbus TCP or for Modbus RTU over TCP. I think the correct answer is: The Vision controllers support Modbus TCP, not Modbus RTU over TCP. Modbus TCP has its own specification by Schneider. Modbus RTU over TCP is what you get if you use serial / Ethernet converters for Modbus RTU communication. For better understanding, read e.g. this: http://www.simplymodbus.ca/TCP.htm 1 Quote Link to comment Share on other sites More sharing options...
Ofer Posted April 28, 2019 Report Share Posted April 28, 2019 could anyone supply a full example of using modbus on the plc side AND on the pc side? I would prefer a python example but a .NET is good too. Quote Link to comment Share on other sites More sharing options...
MVP 2021 Joe Tauser Posted April 29, 2019 MVP 2021 Report Share Posted April 29, 2019 Look in the Visilogic Examples for Modbus on the PLC side. This forum isn't about programming PC applications, but someone may speak up and help. Your best bet for figuring out Modbus in python is your friend Dr. Google. The PC will most probably be the Master, and the PLC will most probably be the Slave (or Server in today's politically correct IT-speak). Like this- https://stackoverflow.com/questions/17081442/python-modbus-library Joe T. Quote Link to comment Share on other sites More sharing options...
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