GPIB comunication

[Falc0n]

Hello,

I have a problem with the remote control of an old multiplexer. I found a driver written in turbo paskal 5.0, which was saved on a 5'25 floppy disk. Now I am trying to interpret this driver in LabVIEW. I use GPIB-USB-HS to connect to the multiplexer.
For testing, I am using NI MAX “Communicate with Instrument”.
I found that when I send the command “%”, it switches the first channel to the multiplexer. But after that, I can't send anything else to the device. I realized that after the command, I have to open “Interctive Control” in NI MAX and send “ibsic” to GPIB. After that, I can send a new character to the multiplexer and it will work.
For the next step, I wanted to create a small test program in LabVIEW, send a command to the multiplexer for it, and then send “ibsic” in the next frame, but I got the error “Hex 0xBFFF0015”. I am sure that the problem is in the second frame because the multiplexer opens the first channel.

So the problem is, why can't I send this command? What is wrong?

[GerdW]

Hi Falcon,

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@Falc0n wrote:

I have a problem with the remote control of an old multiplexer. 

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Which brand/type of multiplexer?

Do you have a manual, that describes the supported commands?

[Falc0n]

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@GerdW wrote:

Hi Falcon,

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@Falc0n wrote:

I have a problem with the remote control of an old multiplexer. 

---

Which brand/type of multiplexer?

Do you have a manual, that describes the supported commands?

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IPACO, I have an old manual and found commands in the old driver. But the problem is that I can send commands from NI MAX Interactive control, but can not send from LabVIEW?

[Falc0n]

I mean commands to GPIB 

[NIquist]

You should always check the error codes to see what they are telling you.  In this case it's a simple timeout.  Almost surely since you didn't add a proper termination character to the string you sent and the device is still waiting on you to complete the message.

Error -1073807339 Timeout Expired Before Operation Completed - NI

Check your manual and see if it tells you what the TermChar should be.  You can also just try RETURN, LINEFEED or both.  They are VERY common.

I also suggest you look at an example like GPIB with VISA functions (Search GPIB in Find Examples...).  Use VISA Open, Close, Write and Read instead of the low level functions.

Here is the example:

See how the error wires maintain dataflow and the reference is closed at the end.  These advanced functions will prevent tricky bugs down the road. 🤗

You STILL may need to append a TermChar to the command you send.  Especially if the instrument is an old one.

They're in the String palette:

Add them to the commands you send like this (Note that this example:

BTW, the reason your NI-MAX session works is that it's smart enough to turn on the TermChar by default. (EOI -- Default GPIB termination character - NI Community)