Tag Change Scripts

Ignition
1

Hello All,

I want to log data in my SQLite database on particular Tag Change status bit. This memory will be Bit memory from PLC and will be on for at least few Milliseconds. I am concerned that I may log multiple readings in database due to this. Can I detect Pulse on PLC memory bit in Ignition Scripting.
I am generating this signal on Positive Edge Detection in my PLC logic. So I think there is very rare possibility of that scenario.
But if any body has come across same situation. Please guide me.

I am gng to write SQL Insert code using this memory bit in tag change script.

Thanks
Ashish

2

If the PLC bit that you’re looking at is only on for a few milliseconds then you probably won’t see it at all! It should be on for at least the time you have set in your scan class that tag is in. The best thing to do would be to have a bit that gets set ON in the PLC that will trigger a transaction group to run in Ignition and then have Ignition set the trigger bit in the PLC back OFF as a handshake. Then you know that you have actually collected the data you wanted.