RS232 In and Out

I need to receive information from a COM port of a computer, process that information, a forward the processed information to another computer through the COM port too.
Is that possible with FEZ Mini? Does it as the 2 COM ports I need? Is any aditional material needed? What exactly?

Hey Pedro,
It’s pretty well documented, but if you plan to use a wired hookup, you’ll need to convert the TTL levels on the mini/domino to RS232 levels. I think there might be a shield for this, but at least there is are breakout boards available, google will find them :slight_smile:
If it helps though, you can see my project at: (link removed)
I use the xbee extension for my domino and the xbee explorer on the pc to make it a usb COM port. I see no reason why it can’t work on the mini. Works really well for me!


Do you only receive from one end and only transmit to the other end?

If that is the case then you only need one COM port. Each port has a pin for transmit and a pin for receive. Now, FEZ Mini also provides pins with RS232 level.
It should be pretty simple :wink: Take the 2 RS232 pin from FEZ Mini an connect one for the data coming in and one to the data going out.

If you have FEZ Mini starter kit. it would be much easier.

You can get this cable

or this(with internal USB to Serial chip)

attach it to the starter kit. and here we go you have the COM ready to connect to the PC.

Thanks for the help!

In fact I’ll need to respond to both PCs. It’s just an ACK or NAK. I’ve to acknoledge the command received and processed to source PC and receive from the destination PC and ACK or NAK too.

Because we are preparing a comercial solution, buing the starter kit will increse a lot the cost.

As I undstanded FEZ MINI already has a RS232 COM. But it as another COM. Is it possible to convert it to RS232? Maybe using the RS232 Shield for Domino.

I saw that FEZ Domino has shields for RS232 and Ethernet. Can I use both at the same time?
Another option is communicate using RS232 with one PC and Ethernet with the oter PC. Is FEZ Domino with RS232 and Ethernet Shileds a read to go solution?


If you are making a commercial product then you need to use USBizi chipset and make your own boards with what you need (2 RS232 ports)

Another option is to use the FEZ Mini and plug the Mini in your own circuit that has 2 RS232 ports.

A third option is to wire RS232 converter to the UART ports on FEZ Mini. Like this one

There are a lot of options. You just need to sturdy the options a little more.

I’m looking to use the FEZ Mini RS232 COM1 port but am trying to find a simple way to handle CTS and RTS from the external device. I note the COM2 port has CTS and RTS but not sure if some conversion is needed as this is not defined as an RS232 port so assuming this is TTL.

Any tips and advice on finding a way to handle CTS and RTS on FEZ mini gladly welcomed.


The are handled automatically by the firmware. Just enable hardware handshaking.

But be aware, the Mini has a pseudo-RS232 on RX/TX and I assume TTL only on any other pins…