Tag write time

Is there any way to improve the time to write the tag and update the screen controls? for example, I have a multi-state button to select a system mode. When I click on the button I get the dotted lines around the control for about a second and then the state switches. I am using the internal OPC-UA server and have the scan class set for 100ms. I also set the client polling rate to 100ms but it doesn’t seem to effect the timing at all. An HMI screen should feel “snappy” and the state should change almost instantly when you press the button.

The scan class dictates how fast you can read/write. What version of Ignition are you using and what driver are you using?

I am using the MicroLogix 1100/1400 driver and I am using Ignition 7.1.5.

How many SQLTags do you have? How many in the 100ms scan class? I did a few tests of my own with a MicroLogix and mine seems quite snappy. However, I only have around 100 tags or so.

Right now I only have 6 tags set up. I just started creating the tags and linking them to the objects on my screen and I went into test mode and noticed the “write pending” dotted lines staying on for quite a while (about a second it seemed). With this few tags I would expect the object to change state almost instantly.

What kind of scan class is it?

Leased mode with 0 slow rate and 100 fast rate. I had the fast rate at 250 and then changed it to 100 trying to get things to go faster. It didn’t seem to make a difference. I will probably go back to 250.

What I have noticed is that the actual write does happen quickly, but the dotted lines then stay on the control for another second before it changes state.

On other thing I noticed is that the dotted lines stay on the control for a really long time if I press the same state that is already selected on the multi-state button.

Just for testing can you switch one to a direct mode scan class to see if reacts faster. I think we may have an issue with the leased scan class right now.

I already tried that. It did not make a difference. I also tested momentary and toggle buttons. I see the same behavior. The actual write to the PLC is fast but the screen is slow to update. This happens in preview mode in the designer and when I launch the client (same PC).