Connecting a Siemens S7-300 PLC to NI OPC Server


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As a part of the final year Bachelor Thesis project I and two others are involved with, I have been tasked with setting up an HMI/SCADA system to control level and flow in several water storage tanks. This is to be done locally via a "Operator Panel" and also remotely over the Internet via webbrowser. These storagetanks and control system is placed on a wheeled demonstration model so that it can be used in classrooms and auditoriums. As such, I have a Siemens S7-300 PLC and the latest edition of LabVIEW (2009 Professional Ed.) available to me. In order to create a HMI system, we will also acquire the NI DSC module as it should have everything we need (NI OPC is included?.

Since this is a bachelor project provided by the school and the school is basically paying for everything, we are on a rather strict budget. This means that we currently haven't settled on a solution for the "Operator Panel" since this would be dependent on how the PLC and panel interfaces. What we would like to do for simplicity's sake is to use a commercial laptop computer with touchscreen capability thus having a low cost "all-in-one" solution, both for local input & control and web publishing capability. Now, most computers today doesn't have serial comports anymore, but rather USB ports.

On the OPC server webpage under the OPC Device Connectivity heading, it is specifically stated "Siemens HMI Adapter for S7-300/400 via Serial with HMI adapter". I assume this refers to the following Siemens product: https://support.automation.siemens....apter_x.pdf?func=cslib.csFetch&nodeid=8773922 (6ES7 972-0CA1X-0XA0).

Does this mean that the OCP server can only use a Serial connection via the HMI adapter for the S7-300 directly? Would it be possible to use a driverless Serial to USB adapter with the HMI adapter, or for example the Siemens CP5711 MPI to USB adapter? If it is not possible to use a USB based solution, We would have to use an older desktop PC with an serial comport or an additional PCI card and that is something we would like to avoid.

Any help on this matter would be highly appreciated.

-- DanJack, NUC Norway
Dan Jack,

Allen Bradley makes an HMI called PanelView Plus, in various models with a basic part number of 2711, and uses a Windows operating system and supports application in C++. The 1200 model, I believe, has both USB and Serial Port connections. In the applications I have seen it is relatively co-operative when using a serial converter into the USB port as well. It also has an expandable RAM device and supports two Compact Flash cards, one internally mounted and the other is insertable/retractable from the outside.

This is about as far as I can take you with any degree of certainty. Good luck.

Hmm. Basically the entire setup hinges on whether or not the Siemens drivers that come with the NI OPC server program allows for communication over USB. If they do, so much the better, then I can basically go with any type of PC I'd like. If not however, I would have to buy some sort of industrial PC or a "all-in-one" operator panel.

I have posted the same question on the NI forums, but there is no answer as of yet. I'd hoped to run into someone here who might have dealt with this kind of specific problem before. If it wasn't for the rather high cost of operator panels in general, I'd go that route. However, I'm on a tight budget.

Unfortunately, I don't even know if the NI OPC program supports virtual COM-ports, so that there perhaps might be third-party cables USB adapters with such drivers, and also support Siemens PLCs.

Fred Loveless

The S7-300 MPI driver in the NI OPC Server does not support the USB to MPI adapter at this time. It only supports the legacy RS232 to MPI adapter or an RS485 connection. You can communicate to the MPI port and program through it if you use the Hilscher netLink 50-MPI adapter.
Thank you for your help. So USB communication is not possible at this time. Then it's off to buy a Panel PC and the MPI-RS232 adapter.

-- DanJack, NUC Norway
So i was just in the same situation, also need to connect the S7-300 PLC to LabView through PC Adapter(MPI--USB).I solved it with the siemens soft--Prodave(.dll/.lib) include several fuctions as load/unload/read/write...
But so... slowly