Howdy

\r\n is ascii for 'carriage return' and 'new line' So it looks to me like '19\r\n20\r\n' is the equivalent of:

19
20

Doing a quick search it appears that the error 'invalid literal for int() with base 10' is when it is reading a float value as an integer, or the variable is an integer and the data is something else. It seems strange that you get a few lines OK and boom, it breaks. Is there any way you can test with a different TTL/USB adapter? I would take a stab that the data from the GC10 is somehow being corrupted or read wrong or something. What I mean is that pyradmon is looking for an integer i.e. '19' but is receiving something different. Either some ascii character or something else that is being received by pyradmon that it doesn't like. Oh, Base 10 simply means decimal, 0 - 9. Base 7 is Octal and base 16 is HEX etc to put it into comparison.

Edit; can you fire up a terminal on your Pi and just leave it printing the cpm for some time. Check for bad characters, carriage returns or new lines that are missing. What you want is a constant stream of the CPM being printed on a new line each time and only that. If you are receiving the odd character that isn't a number that could be your issue.

Hmm, actually I wonder if pyradmon is reading '19\r\n20\r\n' as one reading when in fact that string is actually two readings? As though it hasn't processed the carriage return and new line.

That's great news! I knew with a bit of perseverance you would get it sorted, well done!

Not being familiar with pyradmon I didn't know you could choose protocols. I'll remember for the future.