Siemens Enhanced driver, slow browsing and slow update rate

Ignition
1

We are running Ignition 8.3.3 with Siemens Enhanced Driver 1.3.3, and we are having some issues with it. I would like to understand what we can do to make it easier to manage.

This is what we have done so far:

We added the Siemens S7-1500 to the gateway using the enhanced driver. In the project, we added the complete set of tags from the PLC, about 37,000 in total, to the default tag group.

At first, everything worked fine. Later, when we needed to update the PLC with new tags, I thought the simplest approach would be to remove the PLC tags from the default group, refresh the PLC, and then add the complete set of tags back to the default tag group. However, this was not nearly as fast as it was the first time. It took a long time to browse the tag tree, and adding the complete set of tags again failed.

After some trial and error, and by duplicating the device, it worked.

We also noticed that the update rate is slower than expected. It can take several seconds to get a response, and it may have been slow from the beginning.

Since we do not need all of those tags in the project, I thought it might be a better idea to only add the tags we actually use. However, I struggled with the slow browsing of tags on the PLC. I then decided to add a new device to a new tag group, and that worked very well at first — it was fast again to add all tags.

But that did not last. After changing and removing some tags in the Tag Browser, when I wanted to add them back again, it became very slow to update the tree.

So my questions are:

How do we make sure the update rate is fast?

What is the correct way to solve the slow browsing issue?

2

Never add all the tags in the PLC to your project. This is never necessary, always causes issues.
Add tags only when you need them, deliberately and in a structure that makes sense in the gateway, tags are a gateway level resource, so you shouldn't think of them as a project resource. The way you arrange them, name them and put them in folders will be how every project on the server will see them from that point on.

In reality, it is not Ignition or the server that will struggle with tags, it is the PLC. PLCs are not designed to share their entire memory contents constantly, only to share select parts as needed. As a result, the PLC is designed to accurately control a machine, not to send tags to SCADA. I would guarantee that if you look at the diagnostics on the PLC, it will show you that it is struggling to deal with all the tag subscriptions.

3 Likes
3

This.

Dragging all of the browsable OPC Items into the Ignition tag browser is a newbie mistake. Common with Rockwell, as that has been browsable in Ignition from day one, with similar results. Browsability with Siemens is new in v8.3, and the Siemens users are now falling into the same trap.

OPC Items visible in the OPC browser create zero load on the PLC. Dragging them to make Ignition tags is where the load starts.

1 Like
4

David and Phil have offered good advice, but the behavior you describe still seems a bit weird. After you remove all of the tags, I would expect that browsing should behave as it did before. I'll try to look into it soon. I suspect maybe there were a few lingering read calls to the PLC that were still being processed after deleting your tags. I'll try to look into this a bit.

Determining how many tags you can read and how quickly you can read them will be a bit difficult until we add some metrics for this driver. It's on my backlog.