So, the text you've provided looks like some corrupted JSON to me, in which case you could simply accomplish your parsing task using JSON. CPAN is an amazing resource, and your exploration of Perl would be well served by learning its ways.

The issue with a simple split that you propose is that, in the general case, the quoted elements of a JSON string can contain your delimiters (, and :). You could do this using a regular expression or splits, but it's much easier to do this sort of thing with a state machine and character-wise parsing. And beyond that, it's much easier to use freely available, well-tested code someone else wrote.

And having said all that, with the given example, you can do what you want with (undef, $temp, undef,$tmode, undef,$fmode, undef,$override,) = map split (":"), split (",");, which outputs

Temperature:  70.00
Tmode:    2
Fmode:    0
Override:    0
________
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