If they are both connected to the same instance of ARC the variables are global to that instance of ARC.

Good,, thanks! One more question, if my computer is connecting to a Arduino Board via USB, how can I send data from arduino to ev4 then the ev4 can process the data then sends back the data to arduino?

To elaborate on to what rich said, If your using the same ARC file for both, you can write a script to communicate between the bots.

I.E. You have robot arrive at home base. You would have the robot trigger

$robot1ishome = 1

And the second robot would be using a script to say "ill be right there" like

:loop
IF ($robot1ishome = 1)
sayezb(1, "I'll be right there!")

ELSEIF 
sayezb(1, "Are you there yet?")
Sleep(5000)
ENDIF

Goto(loop)

I can't guarantee the script is totally correct, but it should be close. Use this as an example for writing your own.

As for your arduino question, you can use analog ports on the ez-b connected to data ports on the arduino, and have the arduino send info, or you could also use the i2c or UART ports on the ez-b connected to the corresponding arduino port. Then write a script to have the ez-b read the data.

If you don't want the boards connected but rather communicate over the pc, you could use the sendserial control to send info over the com port, if the arduino can except that.

I see, in the multiple robots, how can I run a specific robots. Like if I want first robot to do dance, second robot to say "hello", and the third robot to play music.

When you send a command you can specify which ezb board to send the command to with an optional parameter... I think below is the format...

servo(1.D0,90) #sends a servo move command to ezb board 1
servo(2.D0,90) #sends a servo move command to ezb board 2
#etc

but this servo() function only moves the servo position, right? How can I call a customized function for different robots.

You would need to configure all controls to use the relevant EZ-B. It's an option on all controls other than the Movement Panel (Unfortunately this is the downfall, you can only have 1 Movement Panel per project).

The other way is to run multiple instances of ARC. You would need to send all variables to each instance of ARC though which isn't an easy task (at the moment - the cloud should solve that soon)

Not quite sure I understand what you are saying... It's not just for servo commands, it's for all commands whether for scripts or controls (Board # options are also available) in most controls as well...)...

Robots are made up of a bunch of scripts and controls right? So build your ez robot project for the first (0) ebz board, then build another robot specifying board #1 then a third robot specifying board #2 and so on...

edit Rich is right, forgot about that... One Movement Panel per project and I think only one speech rec as well... (not quite sure)