CONTROL:
Control command

Power_on/standby/toggle
 D Pulse to turn the power on and standby.  
when a pulse signal is given, the power will be turn on/off(standby)

Input_auto/1/2/3/4/5/6
 D Pulse to select the input or auto mode. 
when a pulse signal is given, the input terminal or auto mode will be selected

Output_1/2
 D Pulse to select the onput. 
when a pulse signal is given, the output terminal will be selected

Emphasis_on/off
 D Pulse to turn the emphasis on and off.  
when a pulse signal is given, the empasis will turn on/off

Front_key_lock/unlock
 D Pulse to turn the front key lock and unlock.  
when a pulse signal is given, the operation by front panel button will be enable/disable

Direct_select_**(in*_to_out*)
 D Pulse to select the input and output directly. 
when a pulse signal is given, the input/output will be selected at the same time

rx$
 S Serial signal to be routed from a 2-way serial com port.
It's a serial communication port for receiving the signal


FEEDBACK:
Status feedback

Power_on/standby_fb
 D High to indicate the current power state.  
This mentions the power status

Input_auto/1/2/3/4/5/6_fb
 D High to indicate the current input and auto mode state.
This mentions the input which is selected and status of auto mode

Output_1/2_fb
 D High to indicate the current output state.
This mentions the status of output which is selected

Emphasis_on/off_fb
 D High to indicate the current emphasis state on and off.  
This mentions the status of emphasis on/off

Front_key_lock/unlock
 D High to indicate the front key lock state lock and unlock.  
This mentions the enable/disable status of front key operation

Direct_select_**_fb
 D High to indicate the current input and output state. 
This mentions the status of input/output which is selected

Tx$
 S Serial signal to be routed to a 2-way serial com port.
It's a serial communication port for transmitting the signal
