A few DataStore Plus questions

[JZerb]

I was just curious as to how the .csv file was going to come out when using DataStore plus on a PVP 7. When the "Trigger" transitions from a 0 to a 1 in the PLC the Float and/or String data that is defined in the DataStore plus setup is captured and put into a .csv file. But my questions are is if say the Float data changed while the "Trigger" is still 1 does that data all get recorded? or does the only data that gets recorded end up being what the Float had in it when the "Trigger" originally transitioned from a 0 to a 1? So say you wanted to record the starting and then stopping time of a cycle on a machine. Would you "Trigger" the datalog to start at the beginning of the cycle then keep it "on" until the end of the cycle, it will then record that end of cycle float data and one would turn the "Trigger" off in the PLC logic. Or would you setup the trigger so that at the beginning of the cycle it came on for a moment, recorded the data that it needed to, then cycled back off in the PLC logic waiting to be cycled on again for the next time it needs to log data, in this case the end of the cycle. Thanks to anyone that can hopefully clear this up for me!

 

[cwal61]

I would capture and store all the Data points in the PLC for the cycle and then trigger at the end of cycle. Each trigger will create a row of data so if you want beginning and end data in the same row then this would be my choice.

 

[JZerb]

ya know, after i typed this up last night and drifted off to sleep that method you mentioned above dawned on me. i think youre right and thats the way im going to set it up. if i were to use different triggers throughout the process the data would end up not being in the same row on the .csv file, which would get pretty messy.

 

[JZerb]

So I recall with setting up the DataStore plus you would have two Boolean tags, one for the trigger then another for the handshake. Once the trigger went from 0 to 1 and there was data being captured the handshake tag would go to 1. Then you would have to write your PLC logic to turn both of those bits back to 0 so the process could happen again when need be. Reading a tech connect article it seems to me that now you don’t need to do that? It reads that once the trigger goes from 0 to 1, the needed data is captured and then it resets itself back to 0, as well as doing the same for the handshake tag. Is this true now?

 

[cwal61]

What I have found, is if you assign a handshake tag it will reset the trigger once the data transfer is complete. I can't say for sure if it will reset if no handshake bit is assigned. I usually use a OTL trigger bit and one shot it. I also use a OTU after cycle complete. I will use no part present to trigger the OTU trigger bit. You can watch the logic and see the trigger unlatch even if the program OTU has not been activated. But I like to ensure that my trigger goes off between captures. I have also found that the trigger bit will even reset if you assign a memory bit in HMI to the handshake bit.


Just a note that you can assign multiple datastore objects to the same file and write multiple rows with different trigger bits. You can use Parameter files and use those to write different information to same file. I keep up with tool hits on machines that have 2000 or more tools. We display up to 40 tools at a time and use parameters to load the page. I use 40 datastore objects and parameters to capture any page that is loaded when tools are changed and the count is reset. I also use expressions to decide when to trigger. On my tool change page I use the expression to decide if the tool has been picked and the reset button has been pressed.

If {#1} and {#5} then 1 else 0


where {#1} = tool selected and {#5} = reset button

 

[JZerb]

Good information thanks! I’ll have to set it up and just see how it reacts. According to technote 520349 it says that once the trigger bit is set to 1 and this the handshake bit is set to 1 as well once the data is written both transition back to 0 now via the Active X control, versus you needing to do that all in the logic like I remember having to do with the earlier versions of FTVSME