I need to send this command= 3! to a device connected to arduino with Tx and Rx.
device connected to arduino with Tx and Rx
Do you know what is it wrong?
the connections are right
The device that I use is an Extron switcher, one of its command is 2! , this command select the input 2 in the switcher through RS232.
Then if this device is RS232 you need to change the TTL voltages into RS232 voltages with a converter or a chip like the MAX202.
Do I need another TTL voltage converter?