serial OS X

[powmri_stu]

I am trying to control a stepper motor controller via a serial line. I have connected the board to a USB port on my Macbook Pro via a GoldX USB-Seial adaptor (which uses the Prolific chip). I am able to connect to the board using Zterm where I can issue commands such as '@00 RMOV 1000' to get the motor to trun through 1000 steps.

I am having some difficulty getting any joy from Labview to control the motor. I have tried pretty much all of the example serial vi's. I can usually find at least one port number that doesn't crap out on me but there is no motion of the motor.  If I do a 'ls /dev/tty*' I get /dev/tty.PL2303-0000201A returned which indicates that OS X has recognised the existence of the USB-serial device.

I see from the discussion board that there have been a few questions about serial port connectivity in OS X with Labview. Does anyone have any clues for me?

Thanks in advance. I am running OS X 10.4.10

Stu

[johnsold]

Stu,

I think all serial ports are black magic (mostly because RS-232 is only an electrical standard and not an operating protocol).

I have run into a situation where a USB to RS-232 adapter was basically shutting down after each character. This was particularly problematic for a port-powered device conected to the RS-232 port. To overcome this I used a property node to assert the handshaking lines used to power the remote devices so that they did not deactivate after each character (or pause between characters). This worked the same way on the Mac and Windows, but even the manufacturer's tech support people had no clue. It took me several days to find this and figure out a work around.

Sometimes a breakout box and a scope can do wonders.

Lynn