I have a PSR 600 and I am using Win 500 software to program the scanner. I noticed that the program lets me select multiple priority channels. How many priority channels can I have
Any conventional channel or talkgroup object can be set for "priority", so the limit is how many of those objects you have programmed.
and in what order do they go to the priority channel?
They're all "peers", with equal priority.
Does one priority channel have priority over another?
No. An object flagged as "priority" will never be interrupted by any other "priority" object.
How does it know which one to go to?
Once per <priority check interval>, and only if no "priority" object is currently active, the scanner checks up to <priority channels to check> conventional channels flagged as "priority".
Also how often does it check for an active channel that is a priority, is there a way to change that to make it seek an active channel faster?
PGM GLOB
"Pri Channels:" = <priority channels to check>, the number of CONV objects flagged as "priority" that the scanner will check each <priority check interval>. 0 = "all"
"Pri Interval:" = <priority check interval>, the time (in deciseconds) between each priority check
(Edit: In Win500, the above two items are on the "General Settings" tab and are named "CONV to check each pass" and "Priority check interval", respectively.)