Double Data logging?

Hi guys,

In our AB PLC, I have setup a counter to increment every time a particular event happens. In an Ignition project, I have setup a historical transaction group to log the counter on change as well as the serial number of the part at that time.

As you can see, data is being logged even though the counter is not changing… Any ideas?


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Looks like you’ve accidentally selected the serial number to monitor for changes.

Not true:

Since a trigger is not being used, it will log an entry whenever either of your values change.

I never found a solution to my problem and so found a work around (not using transaction groups). A colleague of mine is using transaction groups for another project and is seeing the same thing…

He has his PLC go through a sequence and on completion sets a boolean tag which triggers the transaction group to log a bunch of data about the sequence. Here are the trigger settings:

Interestingly, when we use a simple memory tag to trigger the transaction group it only logs 1 row of data as expected…

Consider using an integer for the trigger. Increment it once per cycle. Go as high as you feel comfortable for the value, then roll it back to zero.

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Can you verify that you do not have a copy of this transaction group somewhere else on your gateway writing to this same database table? Generally, when I see double logging like this, there is another transaction group either on the same project or on another project pointing to the same table. Can you confirm that this is not the case?

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Ahhhh, my colleague had 2 other previous version projects that may have been causing this. His understanding was that Transaction Groups only run in the client space which I looked up to be false. He already found a work around for this and deleted the other projects so I can’t verify this was the case but thank you very much, very reassuring to know we have a probable cause so that we can use Transaction Groups in the future.

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I have had this problem and it is the result of having two or more copies of the same project running.<Correction… there were two copies of the project in the gateway and they were both running see replies… transactions do run on gateway> It took awhile to figure out. I wish there were a way to have the transaction group run like a global script since I only want one instance of the transaction group to run but I need to have several copies of the project running on different monitors in different places.
I am using the transaction group to copy data sequentially from a log buffer in the PLC so I can see events that happen in the exact PLC scan order.

The obvious solution is to make a standalone project for running the transaction groups but this adds extra maintenance I want to avoid. Is there a way to do this in version 7.9.X ? What about newer versions ?

Transaction groups do run in the gateway, one only, no matter how many clients are open, even none. Are you sure you didn’t duplicate the project itself?

Now that you mention it… this was from awhile back and someone did duplicate my project.

But today I am having the same duplication issue and coincidentally duplicate logging went away when I closed multiple clients. I will look into it further. Probably a trigger problem.
I didn’t duplicate the project. I will look into it…

Thanks for reply. !

This might be a customized scripted logger? Look for tag change client events that should be gateway tag change events.