Method to check if UDT data has changed ?

Jimbojones

Member
Join Date
Mar 2015
Location
NC
Posts
15
Hello!

I need some advice on how to check if the data in a UDT has changed, without going through each of the tags in the UDT. I use an array of my type UDT for recipe storage.

What I am trying to replicate is a simple checksum ... if the checksum is different for the UDT then what was stored, then flag the need to save the recipe.

Thank you!
 
You'll have to compare each element of the UDT. If it's all INTs, DINTS, or Reals, and if you trust a check sum, then add them up and compare.
 
If you're using Logix5K or Studio5K, you may be able to use FSC or FBC depending on the complexity of your UDT.
 
Within the UDT I do not know of any easy method

However you can use COP to put the data into an DINT (or INT) array and then loop through the DINT array performing your checksum or comparison
the loop can be FSC, FBC or your code
 

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