Hello,

I have a customer that wants to use the data logging function on a PV450. I believe the upper limit for the log memory is 32 MB.

Is there a way to estimate how much memory is used when logging data? e.g. I have 7 pieces of data that are 2 bytes each, plus 12 bit data entries. On top of this I want time stamps. And I assume that the names of variables will also be stored as headers.

So approximately 16 bytes of data plus the time stamp and header labels... Can I assume the headers only get recorded once? Will the 2-byte data only take up 2 bytes each or will it consume 4 bytes? How about the bit data, 1 bit each or more?

The customer wants to know how many hours he can record with data log rate at 1 second.

Thanks,
Phil

According to the developer, the Data Logger application stores the value of the variables in memory in a bit format. So, the size of each value will depend on the number of digits in the value including the number of decimal digits. Each digit is stored in 4 bits and values with fewer digits will use less space. It is an effective way to compress the log data in memory and makes it easy to convert into the CSV format when storing out to USB. But it makes it hard to calculate the size required because it is dependent on the data. Big numbers and numbers with a lot of decimal digits will use more space in the log file. For the best estimate a sample of the typical data could be recorded and then calculate an average sample size per time interval.

Thanks for your reply.

If I understand correctly, an INT16 would have a max of 5 digits at 4 bits per digit = 20 bits. Seems like a strange way to compress data. And if I understand then bit data will also take up 4 bits each.

What about the header data and time stamp?

The timestamp is saved like this YYYY-MM-DD 14:55:02. So the timestamp is 9.5 bytes. The headers are not saved in the internal log file.