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Topic starter
Hi all,
I have a customer that has a specific request. He has some PLCs that have flash memory. In the flash memory, he needs to archive the data from the PLC when the comunication with PcVue is down. The file format used is .csv. This file can be generated with wathever structure is required.
The customer wants to use the proprietary unit from PcVue. SQL is not an option.
How can he import this archived data in the PLC, when the communication with PcVue goes on again. How can he import this .csv file in a propietary unit in PcVue.
Is this possible?
What is the best solution that we can offer?
Thanks in advance for your help. Feel free to ask me any question.
BR,
Enzo.
Posted : 09/06/2020 6:14 pm
Hi,
If the prerequisite is proprietary archives then you could use SCADA Basic HISTORY
History("IMPORTTREND", FileName);
You will need to configure a read only archive unit.
BR
Edouard
Posted : 09/06/2020 6:33 pm
exactly! And that's a problem as it means you must import ONLY.
A better way is to create a basic program using Manager Toolkit that reads a csv file and set each record with the timestamp. It will be recorded as usual.
This program could be quite generic to be re-usable...
Nico
Posted : 10/06/2020 9:01 am
Eventually, "this program could be quite generic to be re-usable", and we can add "but it would not work" 😉
Why: Because when reading proprietary archives (via a log or trend viewer), the storage timestamp is used as the index for querying. And thus, after importing such historical data that are not 'close to real time' in term of storage timestamp, the PLC source timestamp and the storage timestamp can be very different (a gap of a few hours to a few days or weeks), and lead to failures to read recorded data. And by failure, I mean data that will never show up in viewers.
If I am not mistaken, for Proprietary archives, there is no silver bullet. That's why they are said to proprietary, they are not easy to interface with the outside world. And it is both a matter of format (some of you know the fact that index files cannot be tricked with a reasonable level of effort), and a matter of behavior (such as how the storage timestamp is used as an index for querying).
For HDS, you could give a try to the DBImport, some people here may have some experience ?
Regards
Posted : 10/06/2020 1:46 pm
Hehe, OK Benoit but in your sentence : "...the PLC source timestamp and the storage timestamp can be very different (a gap of a few hours to a few days or weeks)" there is the word CAN.
Having such a gap is really not the standard situation and, by the way, it is possible to set this statement as a condition "the PLC time must be synchronized with the Scada time"... 😉
Nico
Posted : 10/06/2020 4:09 pm
If you wish, just note that clock synch between PLC and SCADA server is not the point here.
For the rest, I can only say that by experience, that kind of data retrieval and import to proprietary archives can be designed and operated in some edge use cases only (if any).
Good luck 😉
Posted : 10/06/2020 4:56 pm
Topic starter
Thank you everyone for your answers!
I have enough elements to build up a proper response for the customer.
BR,
Enzo.
Posted : 10/06/2020 7:53 pm