From PLC load memory to SD Card (once a day)

Which PLC are you using?  S7-1500 has the option to copy files.

The PLC manages the SD card writing for you.  You can enable SD card longevity option so the PLC writes to the same memory less often so it can evenly "wear out" the SD card.  It's in the hardware configuration for the PLC.

S7-1200 provides less options, so it matters.

Tedy

Hi all,

I have never used SD card for expansion of the memory before. Probably about to.

So, here is my question. How can I set the system to transfer DataLog file from internal memory to SD card? I don't want to write to card every time system makes a log entry. Just want to transfer the file when it's closed so I can delete it later.

Thanks

Take a look at the industry mall, https://mall.industry.siemens.com and input your favorite memory card (for ex: 6ES79548LF030AA0 24MB MMC)

You can find the datasheet where it lists the minimum life expectancy. 

For 8000 log entries per day, you need an external device to accept data from the PLC and store it.  A PC with simple VB.net application (I think I've seen source code posted in these forums for it) to accept data from a PLC would work.

There is also snap7 open source S7 communications library of software.  Snap7 has a pre-compiled "server", and a "client" that might work for data capture immediately, and use a simple append new data to end of existing data.

There are lots of better solutions than writing to a memory card for that amount of data.  If you were to say 24 writes per day, memory card is probably better.

Tedy

In addition to first thread. What if I don't do anything and PLC takes care of everything. Do you have any experience how long the SD card would last before breaking down? I expect aprox 8000 datalog entries per day. The size of .csv file with 5000 logs is around 3MB.

My understanding is the s7-1500's offer more details on memory card management, including an options to produce an alert @ when 80% of the service life is used.

My understanding is that in general, Siemens memory cards have an IC managing the storage, leveling out the writes for you automatically. I may be incorrect since nobody at Siemens told me this.

Tedy

Hi Again,

I have found a solution not to write each log directly to DataLog but make a long array[200] of logs and when full transmit the data to DataLog. That would reduce the amount of writing to SD card a lot. However. I still can't find any information how the PLC manages data writing to SD card.
Depending on this I will decide if I will make a very long string for one time write to DataLog or the loop which writes complete array to DataLog but one idx at a time.