[PD] problem with arduino digital ins - Pduino-0.5beta8 / Firmata 2.1

[Ingo Scherzinger]

Hi,

I'm having a problem with the arduino digital ins.
According to the arduino website there are pull up resistors inside the
ATmega that get activated automatically when the digital ins are turned on.
This is not the case here with the Pduino-0.5beta8.
When I connect ground to the pin it switches to 0 as expected. When I
disconnect the wire it starts switching randomly between 0 and 1. If I use
an "external" pullup resistor everything works as expected again.
I just read the help file from the pduino and it states that this is the
normal behaviour which shouldn't be the case with the internal pullup
resistors activated.
What's the problem with these internal pullup resistor not getting turned
on?
Is there a command I can (or have to) send to the arduino?

I've tested this with a diecimila and duemilanove and Ubuntu 10.4 and
Windows XP.
Maybe there is a problem with Pduino or Firmata 2.1?

Any ideas appreciated!
Cheers, Ingo