VB - PLC Comms??????

Hi,
I need to communicate between an S7200 and visual basic running on a PC. I have come up with two options.

OPC - I know I can get an opc client and server. There is an active x control which acts as an OPC clien which can sit in my VB. This option is expensive.

Modbus - This is cheaper but i dont know if there is an activex object/ simple source code which can handle this.

Anybody done this? or know of any solutions?
The OPC server/client I was looking at was Kepware but I need to know about the modbus.

Thanks

Please elaborate on the requirements/scope of your project. What are you trying to do? How strong is your programming background?

Kepserver EX with the Siemens Suite is $795. Since you're using VB you can write your own OPC client application for free. Alternatively, Software Toolbox sells OPC Client ActiveX controls.

My advice - if you want to play programmer and roll your own custom app, use Kepserver EX and go to town. If you want to get even more hard core you can purchase native .NET runtime drivers. If you're looking for a simple way to present data on a PC, that's what an HMI is designed for. If your requirements are beyond small and modest you won't save your company money or time reinventing the wheel, especially over the lifecycle of the project. Besides that, you won't be doing the "next guy" any favors.

CyrusTheVirus said:

Hi,
I need to communicate between an S7200 and visual basic running on a PC. I have come up with two options.

OPC - I know I can get an opc client and server. There is an active x control which acts as an OPC clien which can sit in my VB. This option is expensive.

Modbus - This is cheaper but i dont know if there is an activex object/ simple source code which can handle this.

Anybody done this? or know of any solutions?
The OPC server/client I was looking at was Kepware but I need to know about the modbus.

Thanks

Click to expand...

I have to use vb since I am using a camera control active x package. Basically I need the PLC to command the camera to take a picture. I then need to log the picture to HD. I am all for the easy route. I dont want to create my own code.

There is libnodave, which is a free open source driver to communicate with S7, S5 and S7 200.

http://libnodave.sourceforge.net/index.php

You're using a webcam? Does it have a built in web server? What's the model? You may be able to achieve this without writing any software code.

CyrusTheVirus said:

I have to use vb since I am using a camera control active x package. Basically I need the PLC to command the camera to take a picture. I then need to log the picture to HD. I am all for the easy route. I dont want to create my own code.

Click to expand...

Its a standard snapshot camera with a pc controll utility. I mean to control the camera via vb. I need to rename the picure with a set of data from a barcode. Thats why i need vb