Compare Dint to Obtain a Bool Indicating a Change on value

[waterbottle]

Hello guys hope y’all healthy during this time,

Im looking for help in a project im trying to finish. I need to get a bool (ote) when a dint value has change from previous value.

I have a counter for rejection from one machine to the other. The machine dont share anything other than the total number of rejects. Im looking to add a bit of logic for my project but need an idea how to accomplish the OTE every time the Dint value increases.


Rslogix 5000

 

[OkiePC]

Does RSLogix 5000 support the DTR (data transition instruction)?

If not, you can make the same thing with a NEQ comparing the new data to the old data, and then MOV the new data to the old data immediately afterward, setting your OTE bit true along the way.

The DTR is one of the only instructions I know of that has a rung out condition AND modifies one of its data sources. If available, it can save you a branch and a MOV.

 

[Phrog30]

Use a NEQ comparing current value to previous value. Then MOV current value to previous value. Then place an OTE directly after. This output will only be high for once scan.

 

[5618]

NEQ DINT StorageDINT OTE ChangedBit
MOV DINT StorageDINT
ChangedBit will be true for one program scan

Edit - Beat me to it…

 

[Operaghost]

The DTR does exist in the 5000. But I still use the methods above.

OG

 

[waterbottle]

Use a NEQ comparing current value to previous value. Then MOV current value to previous value. Then place an OTE directly after. This output will only be high for once scan.

Brilliant!!!

Worked flawlessly

Appreciate the quick response

God bless

 

[waterbottle]

Appreciate y’all!!

God bless