After line: p openPort: '/dev/cu.usbmodem1a21'., p in Cog is:
	SerialPort(closed, 115200 baud, 8 bits, 1 stopbits, no parity)
is closed because port is nil, in Squeak 4.2.5beta1U is:
	SerialPort(#'/dev/cu.usbmodem1a21', 115200 baud, 8 bits, 1 stopbits, no parity)
port is: '/dev/cu.usbmodem1a21'.

I repeated my test with a virgin copy of Squeak4.4-12327 (before I was using 4.1 and 4.3), also with other macbook pro, the same error.

On 02/04/2013, at 19:00, Eliot Miranda <eliot.miranda at gmail.com> wrote:

> On Tue, Apr 2, 2013 at 4:27 PM, Javier Diaz-Reinoso
> <javier_diaz_r at mac.com>wrote:
> 
>> This example don't work with Cog 4.0.2701 in a iMac OSX 10.8.3:
>> 
>> |p s|
>> p := SerialPort new.
>> p baudRate: 115200.
>> p openPort: '/dev/cu.usbmodem1a21'.
>> 
>> 1 to: 5 do:[:i|
>>        s := p readString.
>>        Transcript show: 'i=', i asString, '=>', s, '<=';cr.
>>        (Delay forSeconds: 1) wait.
>>        i=1 ifTrue:[p nextPutAll: 'M105', String lf.]
>> ].
>> p close.
>> 
>> the same code works ok with the Squeak 4.2.5beta1U, this is connected to
>> an Arduino Mega using only a USB cable.
>> 
> 
> and how does it fail?
>