USB to 422 Converter Woes

[Swamp Thing]

Brian

...now I get it...the "VISA Write.vi" always returns an error ("Could not perform operation because of I/O error"), even if the command executes properly...when I ignore the error it works...any idea what's throwing that error and how to get rid of it? It's a bit kludgey to just ignore it in the code.

Thanks again,

Chip

[Brian_Beal]

First, make sure that there isn't an error being generated from the configure serial port VI.  Probe the error cluster coming out of that.  Next, check all of the com port settings to make sure they match what you are using.  Can you verify that the write is actually happening?

[Jim_Flip]

Brian,
I have always received the same error message. It issues a “Could Not Perform operation because of an I/O error" . This was my original problem and it still issues the error, but for some reason your example gets past the problem where I could not. In your example you have not wired the write error out to the read error in and it continues past without stopping. If I use anything but your code copied and pasted, it fails.

I don't completely care because it now works, but any errors are a source of concern in the long run.

James

[Brian_Beal]

Jim-

Could you post your VI, and I will try it?

Brian

[Jim_Flip]

Brian,
I am at home so I will send it Monday! I would really like to know if it is my system or if it is the controller. I have tried it on two different computers, but haven't tried it compiled at 8.0 yet or altered the default converter settings. After I got your example I went ahead and integrated it into my app and haven't tried anything more on the problem. It works, but it is a concern.
Thanks,

Jim

[Swamp Thing]

Brian and Jim,
I am seeing the exact same thing as Jim...as lonk as I don't wire out of the Error cluster on the Visa Write VI everything seems OK...I see this in LV 7.1 and 8.20.
Chip

[Jim_Flip]

Brian,
Here is the code that previously stopped on the write. Now it continues but still produces the error:

Error -1073807298 occurred at VISA Write in read write 2 serial port 2.vi

Possible reason(s):

VISA:  (Hex 0xBFFF003E) Could not perform operation because of I/O error.

Jim

[Brian_Beal]

I would try using the Configure Serial Port VI instead of the VISA open and property node selection.  See if that makes a difference.

[Jim_Flip]

I get the same errors with either method. It is surprising that my method now works as that was the reason for the start of this thread.

[RavensFan]

I see that you concatenate a end of line constant to your write string.  What happens if you eliminate that?

I was just working with a device where I tried using the Instrument I/O assistant express VI to get a quick start.  On every request that began with a CTRL-B to the instrument, the instrument display showed an error.  I turned the express VI into a front panel.  I found that it automatically put a CR/LF at the end of the outgoing line.  When I eliminated that, everything worked fine.