Protocol/Codes for Programming PRO-64 and PRO-2041

These radios follow a simplified one-way version of GRE's "GRIP" (GRE
Radio Interface Protocol).  While GRIP has a lot of features, the
following is all that is implemented for the 64/2041.

Serial parameters are 2400,n,8,2.  The two stop bits are important.  It
almost works with one, but certain frequencies don't load unless it's two.
Cable design is described in the software packages on this site.

Programming is via lines of ASCII data.  Each line must be terminated by a
carriage return and line feed.

Transfer begins by sending the line

$999*F9

Then, for each channel you want to program, send the line

$902,cccc,ffff.ffff,1*xx

where cccc is the channel number, ffff.ffff is the frequency, and xx is a
checksum.  The checksum is the hex representation of the sum of all the
individual digits in the line.  For example,

$902,0202,0859.0375,1*35

puts 859.0375 MHz into channel 202.

The checksum is

9+0+2+0+2+0+1+0+8+5+9+0+3+7+5+1 = 53 = 35 hex.

To end the transfer (after you've sent all the channels you want), send

$904*EB

400 frequencies load in 45 seconds.  You don't have to load all channels;
just the ones you need.  Channels you do not upload will remain as they
were.