Weight measurement through serial port

[Will_Crowe]

Dear all,

I have a weighing device (Sartorius ED 2245) which connects to the serial port of my computer. I wish to use labview to read from this. However, the serial read VI is returning errors (Timeout expired before operation completed), and I don't know how many bytes to enter as an input into this VI.

Is it possible to read straight from the serial port in this way, or do you have to know what format to expect the string from the serial port to be, in order to decode it? More simply, does anyone have a Labview driver for the Sartorius ED 2245 device?

Regards,

Will Crowe

[chilly_charly]

Don't remember where I got the attached library.

Hope you'll find something usefull there.

Ask again if you are still in trouble 😉

[Will_Crowe]

Dear CC,

Thank you for sending me this. However, I think this is the one that we pulled off the NI website, and we still couldn't get it to read from the particular device, although I have no idea why.. as it looks like it should. Have you any suggestions of what to try?

Thanks,

Will

[Dennis_Knutson]

The first thing I would recomend is that you try to talk to the scale with Hyperterminal. If you can get that to work, you know your serial cable and com settings are correct. The other thing that using Hyperterminal does is give you something to talk about with the vendor if it doesn't work. Most, if not all, vendors will understand Hyperterminal and what to do to get that to work. A log will just scratch their heads when you mention LabVIEW.

Once you get Hyperterminal to work, then you have to look at the driver and see what type of termination character is being sent (i.e. CR, LF, etc)and the format of the data (hex or text). This should all be explained in the manual and if you have an electronic version or a link to one, you can post that.

[chilly_charly]

The first step is to verify that everything is working (balance, cable, computer). Use HyperTerminal to see if the PC receive something when the balance is sending data. You need to know the balance serial port settings (baud rate, number of data bits, parity...). This can be tricky if you have never used the low level commands of Sartorius balances ;). You could start using the default factory settings (although they may have been changed by a previous user)

Use HyperTerminal (the basic utility program shipped with every PC) and see if something is received when the balance Print button is pressed. If something is received, even garbage, you are very close to the solution since you just need to find the proper serial port settings :). If nothing is received, you'll have to find the origin of the problem. And that can be even more tricky than reading the balance settings !

- Check the cable : there are two types of cables according to the wiring of pins 2 and 3. Are you using the right cable ?

- Check the PC serial port : use another port and don't hesitate to try with another computer.

- Check the balance serial port (some years ago, I spent days trying to communicate with a series of damaged balances...). Use an oscilloscope to check the signal on the TxD pin.

Ask again if still in trouble