int eth32_readback(eth32 handle, int port, int *value);
This function retrieves (reads back) the current output value for the specified port. This is the value that was last written by calling eth32_output_byte or one or more calls to eth32_output_bit.
handle - The value returned by the eth32_open function.
port - The port number to read back (0-5)
value - Pointer to a variable which will receive the port's output value.
This function returns zero on success and a negative error code on failure. Please see the Error Codes section for possible error codes.