Command to sent out digital signal to a connected Arduino board
cmd_digital_out(h,pin_no,val)
Board number, reserved for future use. For this version, any number would do
Digital pin to sent the signal
The value of 0 or 1 to be sent to the digital pins with. It is correspond to 0 and 5V
The Arduino board has a set of logical ports (digital) that are used for writing or reading data from a component.
To map a UNO, ports 2-13 are available (0 and 1 are used for serial transmission). For MEGA board, ports 2-53 are available. The port takes the low logic level (0) or logic high (1) which corresponds to the reference voltage.