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Hi All,


Im having a bit of difficulty finding/understanding some of the help information on usage of the SD card and was hoping someone can point me in the right direction.

I believe what im wanting to do is relatively simple, however i cant seem to find any straight forward information on the forums/help files to do quite what im wanting.

I work with heating vessels, using a V700, and when an over-temp event happens would like to log the date/time, current temperature at each probe, Tank level and which HMI screen is currently loaded. (i have different HMI screens set up for a user to select what product they are using with preset temperature set values and overtemp values.)

Currently an over-temp event is triggered by a compare function switching a MB.  If MB is active then 2 contactors will drop out and a shunt trip will activate on the circuit breakers.

can i link the data to log each time this MB is active?

Note temperature probes are PT100 type and the tank level is indicated with a 4-20mA loop.


Thanks in advance


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  • MVP 2023

Hi T.

I'd think along the lines of using a data table that initially only resides in the plc memory.  You would write all your "failure" parameters into the dedicated table on a row designated by a counter that increases each time the table write is initiated.  You would have the MB activation initiate the write before doing the shutdown processes later in the ladder. 

For ease of getting this onto the SD have a look at the post linked below, with a screenshot of how a daily write to SD works.   Help shows data table creation and and how to use them very well.

Alternatively, you could have a manual activation of the same SD write, so that you could do the write whenever you want.  But note that the method in the link relies on it only happening once a day so that file names are not the same.  I have large logging tables that I routinely use the shown method for, and I then periodically download the tables for storage and delete the old ones, never allowing the 64 limit to be reached.

Hopefully I've given you enough outline to have a go yourself.  If you are having trouble interpreting the flow of the link, it is triggered at 23:57 each day, and the trigger effectively latches and only functions once for the minute.

edit PS.......you can break the SI30-38 up into various separate entities if you want, that are then recorded as MIs into the table.

cheers, Aus




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  • MVP 2023

And another PS on the SI30-38.  You can  use the SIs directly, but I do some operations on them, to change them to numbers that are much easier to use when viewing things in Excel.  Simpler to do it in the record itself, than mucking about with Excel.

See the screenshots and it might explain it better.  The MIs are derived from the various SIs.  The trigger is when the seconds in the RTC roll over to 1, and in this case it enables the writing of 2 logs.

cheers, Aus


and the table that results is:



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  • 1 month later...

Hi Ausman,

Thanks for the replies, sorry about the delay, havnt spent much time at work due to the current global situation.

I watched the Webinar on youtube about data tables, with that and your info i have managed to figure it out and get everything working (Attached image of ladder).

I have also just set up copying the DT to an sd card for backup.

I do have a question though,

Are you able to live view the data table through the HMI somehow?




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