socat pseudoterminals with ROS or rosbridge? [closed]

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EDIT: I am running linuxMint Lisa with ROS Groovy

I am trying to connect the output of the roomba driver in ROS to a software that can read a serial port. I created a pair of pseudoterminals that are nulled together. I then created some symbolic links to nonsense USB ports such as /dev/ttyUSB21, ttyUSB22. It is simple to test that these work correctly on their own by using the following code in two separate terminals:

cat /dev/ttyUSB22

Then in another terminal:

sudo echo "hello world..." > /dev/ttyUSB21

The message sent to ttyUSB21 prints from ttyUSB22 as I expect. Messages can be sent the other direction as well (from USB22 to USB21).

I am trying to connect the brown university roomba driver to one of these port, ttyUSB21 for instance. This way, I can attach my other custom software to ttyUSB22, and read in the messages sent by the roomba driver. This other software is a simple roomba simulator I am writing. You should be able to connect to it the same as you would a real roomba, through a serial port (in this case, the pseudoterminals).

I expect a ROS message to use the following path:
usercode-->ROScore-->brown roomba driver--> ttyUSB21 -->ttyUSB22 --> my Simulator.

To test this, I am replacing "my Simulator" in the above with a "cat /dev/ttyUSB22" just to see it print out the message. For some reason I am not able to get anything coming out the cat command when I run my simple usercode.

I can't seem to find any info on how I might get this to work otherwise, and there isn't a lot of data (that I can find at least) about ROS interacting with psedudoterms.

I have seen a little about rosbridge, but I'm not sure if it can do what I need and if so, how I might get it to work.

Any help would certainly be appreciated!