You should probably test if your radio does respond. Let's say your FT-450 is connected to ttyS0:

rigctl -vvvvv -r /dev/ttyS0 -m 127

The -vvvvv is very important since this will increase verbosity, and give
precious traces to developers if something goes wrong. At this level,
the protocol data exchanged will also be dumped to the screen.

Unless some problem shows up, you should be presented with a menu
like "Rig command: ". Enter "?" followed by return to have the list
of available commands. 'Q' or 'q' quits rigctl immediately.

Most wanted functions to be tested are:
'_' get misc information on the rig
'f' get frequency
'F' set frequency, in Hz
'm' get mode
'M' set mode (AM,FM,CW,USB,etc. and passband width in Hz)
'v' get vfo
'V' set vfo (VFOA, VFOB, etc.)

f,F get_freq/set_freq try various (<1MHz, <30Mhz and >1GHz)
v,V get_vfo/set_vfo VFOA, VFOB
m,M get_mode/set_mode FM, USB, LSB, CW, WFM, etc.
passband is in Hz (pass 0 for default)
G vfo_op UP, DOWN
_ get_info should give remote Id and firmware version

I hope it helps. Let us know how it works.

73 Martin, OK1RR