It was 255 because the buffer size was stored in 8 bits but it now should be any size, limited by the available space. It is alloceated at run time and also when using the comopen command from the spare heap, when you do 'sys' it gives the space available, the current release is by defult 920 bytes.
You have to specify a buffer size anyway when using the comopen command, the default 84 bytes is freed up and the new value specified in that command is used.
