If you are using the console you may set up first on all three or four points the right numbers;
On your appliance (in the BIOS)
Serial/COM Port of your PC (if available)
Putty (on Windows)
pfSense (no need because its the default setting)
The default serial console settings in pfSense 2.2 and later are 115200/8/N/1, meaning:
Speed: 115200
Data Bits: 8
Parity Bits: None
Stop Bits: 1
The you could be sure to get out the right output in the console (read able)!