USB & RS232 is full or half duplex.

tpny

Joined May 6, 2012
216
I believe RS232 is. There's tx and rx buffer. The other serial RS485 is half duplex, although u can run longer wires with it.
 

Papabravo

Joined Feb 24, 2006
12,847
USB is most definitely NOT full duplex. There is one signal pair and one power pair in a USB cable. Read Axelson, J.,USB Complete for more info on USB.
 

HDowns

Joined Nov 24, 2010
5
Virtually yes, the program will think that works with a full duplex connection, because each USB-to-RS232 converter has buffers. But if you'll send large data blocks fast you'll see difference.
 

Papabravo

Joined Feb 24, 2006
12,847
Virtually yes, the program will think that works with a full duplex connection, because each USB-to-RS232 converter has buffers. But if you'll send large data blocks fast you'll see difference.
That was not the original question. USB in and of itself is not inherently full duplex. The UART with an RS-232 physical layer is inherently full duplex. A UART with an RS-485 physical layer is inherently half-duplex.

The typical USB to RS-232 converter actually bridges the two network topologies by means of buffers. There may be conditions under which those buffers can overflow.
 
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