# Missing signals or delay in reading them

**URL:** <https://forum.inductiveautomation.com/t/missing-signals-or-delay-in-reading-them/70278>\
**Category:** Ignition\
**Created:** [February 24, 2023, 12:51pm UTC](https://forum.inductiveautomation.com/t/missing-signals-or-delay-in-reading-them/70278 "2023-02-24T12:51:39Z")\
**Posts on this page:** 1\
**Showing post:** 16

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [April 7, 2023, 12:41pm UTC](https://forum.inductiveautomation.com/t/missing-signals-or-delay-in-reading-them/70278/16 "2023-04-07T12:41:08Z")

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See Nick's topic this morning that I just replied to:

> [@Are tagBlocking reads affected by TagGroup updates?](https://forum.inductiveautomation.com/t/are-tagblocking-reads-affected-by-taggroup-updates/72175):
>
> I'm having some issues with synchronising tag reads. The PLC has a number of arrays that store parts information, most importantly the part id. There are 4 arrays, each for different queues the parts are in. These queues have lengths of 50, 20, 20, and 2 parts. Parts move in and out of arrays all the time. I need to read all part ids from these array tags in one hit and combine them together to produce a complete list of parts. I add a column to show each part's location, based on the array. I…

Your simplest solution is to monitor the trigger tag with a tag change event then use `system.opc.read*()` to get the actual data. Subscribed tags cannot and do not guarantee order of delivery.

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