Virtual Null Modem Cable with Linux !!!

After wasting about an 45 minutes on looking for and unsuccessfully running virtual null modem software packages, I gave up and looked for how to do it on Linux.  I knew it had to do with pty (psuedo terminals) and socat .. but I did not know the correct setup.

1 minute of searching and I found this http://blog.avangardo.com/2012/12/null-modem-under-linux-wine/ . Yay ! 

The setup is to get stuff working on Wine which I did not need - I just needed Linux's version of a virtual null modem cable ... Tada !

One socat command with the correct parameters, a chmod and minicom later ... and I got a virtual null modem cable.  Typing in one terminal displays in the other ... Shweet.. now to attempt to test MRL's new Serial service on it.  Which will be a bit challenging, since the Linux machine I'm using doesn't have a monitor !   Woohoo..  we love a good challenge !

But first, rxtx will only get certain devices - some of the filtering is done on device names.. such as ttyUSB or ttyACM - and right now we have a virtual serial port on /dev/pts/2  .. so we make a symbolic link with

 sudo ln -s /dev/pts/2 /dev/ttyUSB77

Now I make a quick script to start MRL with a RemoteAdapter so I can connect to it from a computer which has a screen.

Connected !  And there is a Python service on the remote system .. So we use that to start an Arduino to make sure serial ports are there.

What do I get ?  NO SERIAL PORTS... 
Checking the myrobotlab.log .. I see the following errors

186589 [arduino1] INFO  org.myrobotlab.serial.SerialDeviceFactory  - Got method: public java.util.ArrayList org.myrobotlab.serial.gnu.SerialDeviceFactoryGNU.getSerialDeviceNames()
check_group_uucp(): error testing lock file creation Error details:Permission deniedcheck_lock_status: No permission to create lock file.
please see: How can I use Lock Files with rxtx? in INSTALL
 
GAH ! ... even though I gave permissions to open the file - I don't have permissions to remove or create a lock file which is necessary for rxtx :(
 
Alright, tired of this .. I run the script as root...
 
 
WOOHOO ! and there is ttyUSB77 !!!   But I'm not going to connect with the Arduino..  because we want to test the new Serial Service !!
 
So I start a Serial Service.
 
WooHoo !  It appears to be connected !
 
Now to send some data ...  I don't want to connect again so I don't want to run that part of the script, so I simply comment it out (however, this really should be fixed so that connecting a second time does nothing instead of messing up the connection - which I think will happen)
 
 
Next I try a series of write commands .... guess what the ascii values are for these integers !!!