visa read

[huskerli]

Hi all,

I am having a visa read issue now and wondering anyone can help.

I wrote my own Agilent driver and now looks like anything is fine and I can get the right value which is around 1.7 from the instrument itself. Now I wanna the right value been read from the visa. It always give back to me 9.91E+37 and I am not quite sure why

Thanks

[JÞB]

9.91E+37

is "Agilient -Speak" for Overrange.

[Dennis_Knutson]

What is the instrument? What is the exact string you get from the VISA Read?

[huskerli]

Thanks

But I was wondering why the instrument itself can read the right value but the visa can not?

The instrument read 1.7 which is in the range from the Agilent range table, do you know what is the overrange for?

[huskerli]

Agilent B2901A is the instrument I am using

The exact string I get from the VISA READ is (see the png file)

Thanks

[Dennis_Knutson]

We don't know what VISA can or cannot read since you did not provide that information. Since you did not provide the model number either, no one can tell whether you have used the correct commands.

[Dennis_Knutson]

So, the B2901A has a real driver from NI. What do you get with that?

[billko]

Maybe it's something to do with auto-ranging?  Like maybe you have to wait until it's done auto-ranging before reading the value?  Maybe you have to make the autoranging command into a *OPC? query so that the VI won't try to read until it's done autoranging?

[Dennis_Knutson · Accepted solution]

I would also hope that you are doing the majority of your debug in MAX. I would also recommend you do an ERR? query to see if the instrument will tell you anything.

[huskerli]

It seems like as longas I have a "INIT" in the SCPI code, I can not get the right value from the VISA read. If I get rid of the "INIT", it will be read the right value.

I do need the "INIT" because I wanna it performance like a pulse. I think the reason why I can not read the right values becasue I am currently using "MEAS;VOLT?" command which is suppose read one value only. But with "INIT", I am going to read five values because I am set up count 5 times.

I think if I change the command to "MEASure:ARRay:VOLTage"it may work.

I just wondering is there anyway I can read a array from the VISA read?

- i tried "string to byte array" but did not get it

Thanks