How do I communicate with a Sartorius balance in LabVIEW 8 via a serial port?

[LaRosa]

I am trying to collect data from a Sartorius scale at about 20 samples per second and record each measurement to a file.  I have made a simple program using the VI's from the Sartorius drivers library present on ni.com.  Basically, I use the Sartorius_Initialize vi to initialize the scale (i.e. find appropriate serial COM port, appropriate data interface settings, etc).  Then within a while loop I use the Sartorius_Print vi to get the measurement from the scale and save the data to a file.  Finally outside the loop I use Sartorius_Close vi to close the COM port connection.  Also, I use a wait 50 milliseconds inside the loop to achieve my 20 Hz sampling rate.

The problem is when I open my file, I find that the data has only saved 10 times per second, not 20.  I've tried bypassing the use of the Sartorius_Print vi, but I can't seem to establish a working communication with the scale.  I've tried using Instrument I/O (express VI) to query and parse, but it works only sporadically.  I should be able to just send it the print command ("P") but it's not working.

My 2 questions are:

1.  Does anyone have any idea why the data would be saving only 10 times per second and not any faster?

2.  How can I communicate with the Sartorius scale (either Instrument I/O or VISA read/write)?  The manual says to use the command "Esc P CR (carriage return) LF (line feed)"  How do I write an the escape, CR, and LF commands?

If it helps, I can attach some VI's I've been working on once I'm at work tomorrow.  Any help is greatly appreciated.

Thank you.

[Albert.Geven]

Maybe the balance only measures 10 times a second.
The 50ms delay can be removed in that case because the delay in the while is already sufficient due to the balance

[LaRosa]

Albert

I suppose that could be, although there is nothing stating this in the scale manual, and there is no option to change the rate at which it can spit out data, other than the controlling software (i.e. LabVIEW).

Any other suggestions?

[AnalogKid2DigitalMan]

Contact Sartorius Tech Support directly to find out the max rate the scale can send out readings.

I can't image it would too high a rate since scales are typically used to measure static loads and the device needs time to settle down before an accurate reading can be obtained.

[Wayne.C]

Try this link for info on hex characters.

http://digital.ni.com/public.nsf/allkb/77C8F61D36F5A23086256634005ACB38