Many, many moons ago (early 90s)I had reason to collect data from a PBX system that was sent out over an RS232 connection. I found that I had to read a line at a time instead of a fixed block in order to get reasonable data chunks to work with. It looks like you have a similar situation to that.

I haven't had a chance to grok Device::SerialPort yet, but I would suspect it has some kind of input function that is similar to readln that would be suitable.

Assuming that is the case, then it should be relatively simple to bring in a line at a time for parsing/storing and then processing the collected data whenever the closing "Checksum" entry is detected. Doing a split /\s+/ might come in handy for that. (I tend to be partial to dispatch tables for working with record types.)