In conjunction with writing to RcWare DB, IPLC5xx can temporarily store values in the event of a database connection failure. a common question is, how many values will fit in the buffer? Empirically, this is based on 20,000 values per 1 MB buffer. The buffer size is configurable, the recommended values are up to 10 MB, which means around 200,000 samples.
Just to give you an idea - when sampling every minute, you can buffer 130 data points for 24 hours.