@sparkfun regarding GT-521Fxx… specifically regarding change baud rate cmd… can someone explain how one is suppose to fit a check sum that exceeds uint16 (word) range into a word? This is not possible. Was this cmd ever tested? Try 115200 bps… 
Hi Spud.
Sadly SparkFun doesn’t manufacture this part and we’re not aware of a way to change the baud rate on these. You might try contacting the manufacturer to see if they have a more comprehensive data sheet or instructions on how to change the baud rate. The email address I have for them is: