Reading Tags from Siemens 15xx PLCs

[gharesh]

Hi
I am new to UA stack and want to explore it for developing solution for one of our client. They have Siemens 15xx series PLCs

I want to develop a .NET based web application to read tags and alarms from PLC. The PLC has OPC UA enabled. I have following questions

1. I will develop .NET web application using UA .NET Client SDK
2. Do I need to use UA's OPC/UA Server software to connect to the PLC? I do not have any other OPC UA Server product currently planned
3. What is advisable to use UA's OPC/UA Server or UA Gateway
4. How many tags I can read per second
5. Is there a documentation/recommended architecture diagram for connecting to Siemens PLCs?
regards

[Support Team]

Hello,

1. I will develop .NET web application using UA .NET Client SDK

We have no particular expertise with .NET web apps, but you should keep in mind that OPC UA is unlike plain HTTP not sessionless. So you probably want to setup one session between the PLC and your client (the web server) and store the interesting variable values and alarms in stock. The web request will than only be answered from the intermediate storage.

2. Do I need to use UA's OPC/UA Server software to connect to the PLC? I do not have any other OPC UA Server product currently planned

To connect to an OPC UA server (here shipped with the PLC) you only need the client SDK.

3. What is advisable to use UA's OPC/UA Server or UA Gateway

The Siemens PLC ships already an OPC UA server. The client SDK should be enough.

4. How many tags I can read per second

The limiting factor is usually the server. So it depends on the capabilites of the server/PLC you use. OPC UA supports subscriptions, where you can monitor variable values and get notifications on change. That way you do not need to cyclicly poll the variables.

5. Is there a documentation/recommended architecture diagram for connecting to Siemens PLCs?

There is no difference in that aspect between the Siemens OPC UA server and any other vendor. I'd start with the client tutorials: https://documentation.unified-automation.com/uasdknet/3.2.2/html/L1ClientTutorials.html