How big is the message queue in GPIB?

[MimiKLM]

Hi,

I'm wondering how big is the message queue in devices woking with GPIB interface?

Can I for example ask the device to deliver some results from the SpecAn first and put them to the output queue for example:

(pseudocode)

Put Marker 1 value to the message queue

Put Marker 1 value to the message queue

Put Marker 1 value to the message queue

Put Marker 1 value to the message queue

Put Marker 1 value to the message queue

then read them back to the computer.

Get Marker 1 value from the message queue

Get Marker 1 value from the message queue

Get Marker 1 value from the message queue

Get Marker 1 value from the message queue

Get Marker 1 value from the message queue

Instead of doing like below:

Put Marker 1 value to the message queue

Get Marker 1 value from the message queue

Put Marker 1 value to the message queue

Get Marker 1 value from the message queue

Put Marker 1 value to the message queue

Get Marker 1 value from the message queue

Put Marker 1 value to the message queue

Get Marker 1 value from the message queue

Put Marker 1 value to the message queue

Get Marker 1 value from the message queue

?

Can the queue holds a lot of results coming from a few measurement requests to be read back as the block?

Is it vary from one device to another or is itdefinied by the GPIB standard?

[Makoto]

This is depending on device's design and, whether if the Put and Get action is forming a pair (such as Query and Response) or not.

If the device is compliant with IEEE488.2 or SCPI standard, and if the Put and Get are a pair of query/response, there is an obvious rule.

IEEE4882 and SCPI specifies a rule that a command resets the pending response cue that was generated by the previous query.  

Example:

MARKER:VALUE 1

MARKER:VALUE?

(you can read an answer --- 1)

But,

MARKER:VALUE 1

MARKER:VALUE?

MARKER:VALUE 2

(you can not read any answer  because the old query was cancelled)

[MimiKLM]

Makoto,

Many thanks for the info. t was very helpful. Especially this statement:

---

(...) IEEE4882 and SCPI specifies a rule that a command resets the pending response cue that was generated by the previous query. (...)

---

Any chance you can reference the document in which these feature is described?

Cheers.