Serial Communication

[K C]

Strange that there is a difference between LV and MAX. What version MAX you are using. If it's 3.0 it should be OK that is the version shipped with LV7

[JohnGalt]

It's version 3.0.2. I haven't been able to run my tests yet, as the instruments are still in use. I will let you know when I get the needed results.

[JohnGalt]

Ok, so I still have not been able to play with the Omega, but I ran your program, and instead used it for the Dressler RF Power Supply (with the appropriate commands, of course) and nothing happened. I seem to get a VISA read error. I will try it with the Omega as soon as possible to see if there s a difference.

[JohnGalt]

Ok. I just realized something that may be useful. The error seems to be from the read, rather than the write. This is odd because even the basic write commands don't perform as intended because, on the Dressler at least, I cannot even turn it off remotely. I think perhaps the error does not come on the write because it just needs to send the data and not recieve. I don't know where this is going, but I'm just specuating as I have no idea of what to do. I am also getting the aforementioned error again. I begin to wonder if it has anything to do with the problems. It does appear when the VISA names are loading. Perhaps the computer is not being told where to send the data due to this? If this is helpful, use it. If not, ignore it.

Thanks again,
JohnGalt

[K C]

Hi,

The  Dressler 'thing' is new for me    so I leave that to you.

The VISA read error you get; can you tell me the number of it.

When you say: ' It does appear when the VISA names are loading'  what do you mean ?

[JohnGalt]

Ok. The VISA read error is: 1073676294 in decimal and 3FFF0006 in Hex.
About the other error message. It's the one from earlier in the forum. When I load a VI with any VISA name functions it it, this error window pops up that says [ The instruction at "0x1ca12b95" referenced memory at "0x00000000". The memory could not be "read". Click on OK to terminate the program.] I have no idea what it means, but it is definitely related to the VISA name functions, whether constant or control.It is odd, however, that it continues to let me run the program and even loads the Visa functions properly. Perhaps this is behind the issues with communication? I have posted this in this forum before, but people seem to ignore that part. It might be unimportant becaus of that, but asking you about it can't hurt.

Thanks,
JohnGalt


OK. New question. I was talking to someone about this the other day, and they recomended trying A/D communication with the devices that are having issues.  I have some things on this program running through A/D and it works well. But none of these others have analog outputs. Can you perform A/D communication without analog outputs, like through the serial port pins or something? If so, that would be amazingly useful, then I could make the whole thing really simply.

Thanks again,
JohnGalt

Message Edited by JohnGalt on 12-02-2005 12:38 PM

Message Edited by JohnGalt on 12-02-2005 12:38 PM

[K C]

Hi,

The error you get is not an error but a warning. It is telling you that it is possible that there are more bytes available than you red. See attachment.

I really don't know what you mean with A/D communication.  Can you explain this further?

[JohnGalt]

How do I get it to stop showing the warnign and actually read the data?

I was just wondering if there was a way to do A/D communication without an Analog output. I can get the A/D working.

[K C]

To get rid of the warning just delete it from the error cluster or ignore it. LV will not come up with a error popup because it's just a warning.

When you say A/D comm.  I read Analog / Digital comm. Still don't know what you mean.

We are talking different languages and I am not talking about English and Dutch.

Give it another try to explain the A/D comm. thing.

[JohnGalt]

The problem with the warning is that Labview does make an error pop up for it and ceases execution once this happens, so I don't get any data out of it. I don't think that is normal.

By A/D I mean to say that I am trying to do analog communication with some instruments. It has the little analog out port on the back which I conncet to a digital port card with a simple piece of wire. The wire doesn't have any ends on it. It's just a piece of wire. What it does is that the temperature controllers put out a certain voltage per degree celsius, and the computer reads that voltage and tells me what the temperature is from that. This works quite well within a tolerance and therefore would be quite excellent for this program, but most of the instruments do not have analog ports, so I wondered if it was possible to communicate with them like this, but without the analog port.

Might there be something wrong with the way Labview is communicating this data to the devices which makes them unable to read it? Because the loopback tests work, but the communication with the instruments does not. I wonder if maybe it is trying it in some sort of code or language the devices don't recognize? Just thinking, if it has any possible validity, let me know.