Best practice reading tags in a loop

Ignition
1

Hi!

I have a script similar to this (don't take literally the script is just an example):

objects = []  # list of objects
for obj in objects:
    tag = system.tag.readBlocking([obj.get("fullPath")])

    # do something

    results.append()

return results

However, I'm wondering if it would be better to read all tags at the same time and then process them.

objects = []  # list of objects
paths = []

for obj in objects:
    paths.append(obj.get("fullPath"))

tags = system.tag.readBlocking(paths)

for t in tags:

    # do something

    results.append()

return results

Note that the object list could be about 1000+ items long depending on the plant.
What do you think?

2

Yes! Bulk reading the tags is much better than reading single tag at a time.

3

This is an understatement! You should never read individual tag paths in a loop. It can and will significantly slow down your script, particularly with higher tag counts, not to mention put additional load on the gateway

4

Yup. And if you're doing it because you need to read a couple different tags from different areas over and over, learn about zip() and how you can use it with multiple lists generated from bulk reads.