Question

I need to develop a simple website to display some values that are inputted to a PLC connected to a hardware Gateway( HMS AnyBus AB7007) already installed that converts RS485 Modbus to Ethernet Modbus TCP/IP. I am developing my code using .Net (C Sharp)

As I am quite a novice in PLC interfacing, is there a component, AcitiveX control or dll etc (low cost or preferably free:) ) that I can use to communicate with this gateway and get the required values to display on my webpage. I am not aware if a webservice on this gateway already exists.

Any help is sincerely appreciated!

Answer 1

The HMS AnyBus has a built in web server. It has to be set up correctly (see the manual here : http://www.hms.se/upload/110-3445-ABC-EIP_2_04.pdf) but can be used to serve, among other things, data stored in the input and output data areas of the device.

Check out the section on SSI (Server Side Includes) on how to use those special tags for including dynamic content in a web page. You shouldn t need any third-party software, at least I don t think so.

Perhaps to elaborate a bit - what you would do is set up a simple html document (with the SSI tags) directly on the AnyBus which displayed a list of the relevant data points you were interested in. If you were writing a page to be served from a separate server, your code there would query the web page on the AnyBus, parse the data, and format it however you wanted for output to your new, more elaborate, web document to be served from your main server.

Answer 2

Reading data via built in Anybus web server is too slow if you want to read many tags. Anybus is a gateway, and your Anybus model is a gateway between MODBUS RTU and MODBUS TCP networks. This means that it is a MODBUS TCP server for the ethernet side of the gateway, and it is just a TCP server at port 502 which you can access from .NET with library like this: http://code.google.com/p/nmodbus. Modbus TCP standard allows concurrent access, so you will not have PLC problems if you read data this way.

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