Instrument I/O Assistant RS232 communication problem

[ikletti]

Hello!

I am currently trying to create an instrument driver for a Ballard "Nexa" fuel cell with the Instrument I/O Assistant.

The fuel cell data is 43 byte sent every 200 ms at 9600 Baud (8N1). I do have a working communication, because I can see the data coming in when I´m using an ordinary terminal program. The Instrument I/O Assistant however does not seem to receiver anything.
Here´s what I do / what I see:

1. Create an empty VI


2. Place an "Instrument I/O Assistant" block on the block diagram, the Instrument I/O Assistant windows pops open.


3. Choose device: COM1 or COM2, depending on where the Nexa is connected (Choosing different devices has no influence on my problem)



4. Add step "read and analyze"


5. Click "Run this step" to read the data coming in from the serial port, but nothing happens until the the timeout set on the choose device tab has expired, then I get a timeout message (see attached picture).

I added a RS232 diagnostics plug that has blinking LEDs while data is flowing to make sure there is data coming in while the assistant is running.

I a previous thread, I read that the Instrument I/O Assistant has a bug concerning the locale settings of windows:
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=5065000000080000002DBF0000&UCATEGORY_0=_49_%24_6_&UCATEGORY_S=0&USEARCHCONTEXT_TIER_0=0&USEARCHCONTEXT_TIER_S=0&USEARCHCONTEXT_QUESTION_0=Instrument+I%2FO+Assistant+is+not+communicating&USEARCHCONTEXT_QUESTION_S=0

So I tried the same after switching my locale settings from german to english, but with no success, the I/O Assistant still seems to see not input.

Does somebody have another s
uggestion? Has anybody written a serial read/parse VI from scratch that he/she might share so I can use that as a starting point, if the assistant keeps failing for me?

Thank you,

Ingo.

[ikletti]

Hello again.

I did some further testing and switched from no flow control to RTS/CTS flow control. What I observe is that the terminal program only starts transmitting when I hit the "Run this step" button in the I/O Assistant. This must mean that the serial communication itself is working, but I don´t get any data displayed.

Does someone have a suggestions to this one?

Ingo.

[TN]

Hello Ingo,

may be it helps you to develope a labview instrument driver. Else I don't have any idea for your application.

http://zone.ni.com/devzone/conceptd.nsf/webmain/6100BC4CA014910786256E4A006FE675

Best Regards
TN

[ikletti]

Hi TN,

As I just started using LabVIEW, developing an instrument driver seems like some pretty heavy stuff. For now, I´ve managed to have someone else write the communications backend, I´ll only do the data conversion and display. But I´ll for sure take a closer look at that communications VI so I ´ll get it done myself next time...

Anyway, thank you for your reply, I appreciated it.

Ingo.