Dear experts,

I'm learning about OPC communications and reading Tags from PLC as part of student project. I hope you'll be able to help me by answering these questions in order to save time because this is very broad topic.

1. OPC server can be found in SIMATIC NET tools. What type of licence it require in order to be used, or can I test with trial?

2. Is it possible for training purpose to use PLCSIM instead of real HW PLC to test OPC?

My intention is to try to make simple application as OPC client to read some variables in DB in PLC program. When I learned STEP 7 basics, I used PLCSM a lot.

Hello Aden,

ad 1: the OPC server feature is nowadays in every S7 1500 CPU. It is possible to activate it in the settings of CPU and then select appropriate licence version. The size of the OPC license depend on the type of PLC used (details you can find in industry mall or in the TIA selection tool). Of course legaly it is mandatory to buy the OPC license, if you are going to use it, anyway for test purposes ...

ad. 2: I personally didn't try it in the PLC sim, but in details of PLCSIM advance you can find, that OPC UA functionality is supported, so I suppose, it is functional.

Regarding the PC application... I did the similar application last year and I can recommend the application example from Siemens - see this sample.

Regards Josef

Hello JBee and thank you for the answer.

I have heard that S7-1200 and S7-1500 have some very cool features like web and OPC servers,

However I have access to more than 10 years old S7-315 2 DP PLC. So my idea was to play and test with PLCSIM and then later try with real world PLC controller.

Is OPC UA now a "standard" OPC? I know about DA for real time data and  HDA with historical values.

I'll look into UA. What confuses me is the fact that WinCC installation also contains OPC server, when as far as I know OPC can se used to get data from PLC and to build some kind monitoring application in third party programming software such as C#.

I'm not sure what is the purpose of OPC with WinCC when WinCC is already for monitoring and controlling the process.

As far as I understand the OPC problematic (I'm definitely not an expert !), originally the OPC standard (OPC classic) contained various variants (Data access, Alarms and Errors and Historical Data Access) and this every variant was designed for special purpose. The newer version of OPC standard (OPC UA) should now cover all of the classic functions and should be also backward compatible.

Regarding of OPC UA server in HMI panels - my understanding of this functions is following:

Sometimes any part of information from the process could be out of the PLC (only in HMI panel). For example you have number of named component, which are inputted by the operator. In PLC however you don't want to work with the names and works only with component number in order to save the PLC resources. Anyway if you want to get the names of the components (for example for the data logging), which are stored only in the internal HMI tags, you are not able to read out this from PLC's OPC server. Therefore you are able to run the OPC server on both sides - PLC and HMI panels.

Hello,

I have made a simple test. I have used Matrikon free OPC explorer. I have created a simple wincc application and I changed different values of a DB in PLC program that was downloaded to PLCSIM.

Matrikon OPC explorer sees WinCC OPC server and its Tags without any problem. Now, I'm not able to find an application example how to create an OPC client with WinCC OPC server. I have found client in C# but for Simatic NET OPC.

But since Matrikon (third party client) can connect and explore Tags on WinCC OPC, I assume it is possible to write customized OPC client to read and represent data in appropriate form. I hope someone here has done this before.

Thank you! 

Hello Aden,

definitelly it is possible. I did it. See the sample project from my first answer -

https://support.industry.siemens.com/cs/lt/en/view/42014088 

I used this example and rework it in order to meet our requirements. I tested it only with Simatic PLC and we use it more than year for data logging. And again if I understand it correctly, this app should run with all OPC UA servers, since the standard should be the same. Anyway bugs could be everywhere :)

Regards

Josef

Hello Aden

I think you are mixing informations...

first of all, your S7300 PLC cannot do  OPC Server or Client for its own. SO you need an OPC Server that can connect to the PLC with S7Communicatn channel.

you can use any OPC Server software that can do this like Comfort Panel, WinCC Advanced RT, WinCC Flexible RT, WinCC Professional RT, WInCC V7.X, Simatic NEt OPC Server, and a huge amount of 3rd Party Software.

This is the Server Side, some of them can do OPC DA (DCOM) and also the newer Specification OPC UA.

On the Client Side you are free to use every Client that supports OPC Data Access (binary) and OPC DA(DCOM) or OPC UA.

If you only can use a Simulation of PLC Sim then you need a OPC Server that you can also simulate with a connection to PLC Sim, like a Siemens HMI.

I Think a Simatic Net OPC Server can only connect to real PLC because it runs in a PC Station and not in a Simulation mode on the Engineering Station.

With a S71500 PLC you can simulate only with PLC Sim Advanced the OPC UA Server (only with none Security).

Its here always much easier to use a hardware PLC.

Bye Murof

JBee and Murof, thank you for your support. Yes, I did mix some information. Since I don't have hw Plc to test, the best solution for me is to use plcsim. That is why I made setup with PLCSIM and WinCC. I used wincc runtime just to show three variables in a shared DB. I used OPC matrikon explorer and found that WinCC OPC sever is active, so I,successfully connected to it and saw tags. Now I will use this OPC server to make opc client to connect and to log data. 

JBee, did you use HDA OPC server to log data? If I understood correctly, historical DA is for past data.

Hello Aden,

no, PLC S71500 are now using OPC UA server - the newer standard of OPC, so I use this one. With older OPC HDA standard I have unfortunately no experiences.