How can i control my siemens s7 plc via excel/visual basic


Thread Starter

Arjen den Hartog

I want to control my plc with visual basic / labview.

I have a computer with the cp5511MPI/Profibus communication card and the 318 PLC from siemens.
I d'like to make a testprogram in visual basic/labview with which i can read and write to DB's in my plc.

I heard that such things are possible with an OPC server.

- Is this possible?
- How can i install the opc server?
- How can i talk with the opc server in visual basic.

In fact, there is an OPC server from Simatic Net.

I´ve made several app´s in VB with this one, and the results are more than feasible.

The goal is to develope your own OPC client to suit yor needs.

I have some VB Samples Using OPC Servers which I can share.

You can contact me directly at:


The Siemens OPC-Server for S7 plc's has one great disadvantage: your 318 plc is not equipped with an ethernet interface, so you need to retrofit it, and both hard- and software a very expensive.

it's much easier if you access the plc through the mpi port. i've done this with labview, where i implemented a third party DLL. It works great.


Max Penninger

If you are already using ProTool/Pro RT for testing OP-projects or PC670-Projets, you can also use this ProTool-Runtime as an OPC-Server.
For small programs that are not using lots of tags this method is very useful. You only have to add the needed tags to your Protool-Project, start the runtime and then connect your vb-program to this OPC-Server.

The big disadvantage of this method is, that you need more expensive ProTool-RT-licenses, if you need more than 128 tags.

I normally use this method, if there is already a PC670 built in for Operating.