Slitherine

local myunit =  ScenEdit_GetUnit( {name='SAM Bn (SA-21a/b Growler [S-400 Triumf])', guid='9c291657-7c61-4935-a6d3-25face9f7897'} );
--example adding 20 extra channels for sa21\25 missile links, change for what your unit needs. 
ScenEdit_UpdateUnit( {guid=tostring(myunit.guid),mode='add_comms',dbid='267'} );  

--If you want to check a units comms list before or after you can run this to dump output just make sure it comes after the 'local myunit' line above so that 'myunit' exists for this part of the code:
print('--comms list---');
for i, v in ipairs(myunit.components) do
   if v.comp_type=='CommDevice' then
   print(v);
   end
end
print('--end comms list---');

quote:

ORIGINAL: KnightHawk75

Another option is just pop into the LUA console in the editor and run the following AFTER Changing the name= and guid = parts to match your unit (which you can get from right clicking the unit and selecting scenario editor\copy id to clipboard and then pasting into console script:

local myunit =  ScenEdit_GetUnit( {name='SAM Bn (SA-21a/b Growler [S-400 Triumf])', guid='9c291657-7c61-4935-a6d3-25face9f7897'} );
--example adding 20 extra channels for sa21\25 missile links, change for what your unit needs. 
ScenEdit_UpdateUnit( {guid=tostring(myunit.guid),mode='add_comms',dbid='267'} );  

Then press Run.

--If you want to check a units comms list before or after you can run this to dump output just make sure it comes after the 'local myunit' line above so that 'myunit' exists for this part of the code:
print('--comms list---');
for i, v in ipairs(myunit.components) do
   if v.comp_type=='CommDevice' then
   print(v);
   end
end
print('--end comms list---');

Also in some cases extra 'Comms' will get added automatically if adding certain Mounts, usually it's a vehicle component for SAM sites that do that, but not always, just saying. For example on the s400 if you add a Vehicle GraveStone 92N2 as Mount it will also add comms links that come with it. Note if you remove the mount though the comms entry that was added will get removed (most of the time anyway). Just wanted to mention it as another round about way to do this without code or ini files, but it will not apply to all things, like if you wanted to add milstar comms to said unit you must do it via LUA or ini's.