modpoll
-b 4800 #          Baudrate
-p none #          No parity
-a 1 #          Slave address (1-255 for serial, 0-255 for TCP, 1 is default

-r 13 #          Start reference (1-65536, 1 is default)
-c 1 #          Number of values to read (1-125, 1 is default), optional for writ
ing (use -c 1 to force FC5 or FC6)
/dev/ttyUSB0