Passing control to and regaining control from an SCPI/IEEE488.2 compliant instrument

[Sfiso Myeni]

Hi

May anyone please help me with this problem:-

I've got a GPIB card initialised to be the system controller and a
Rohde & Schwarz ESN Test Receiver that is a device in the ssytem.

I find that after passing control to this receiver using the following
commands, I fail to get it back to the GPIB card, as a result I end up
having to manually reset the receiver by turning power OFF/ON.

The commands that transfer control from the card to the receiver are:-
These commands are sent using a Send(int addr,char * cmd) library function.
Here I only give tou the command sent, but my program addresses the intended

instrument.
"*PCB 21" //tells the receiver where to return co
ntrol later
"*PCB 23" //23 is the receiver's address
"LISTEN 21" //21 is the address of the GPIB card
"TALK 23 TCT" //receiver takes control

My problem is how do we tell the receiver to return control OR how does the

receiver know when it is time to return control to the card and how does
the card
wait for this control to come back.

I feel I'm missing a concept regarding setting up these system players to
effect this.
Could any one please take me through the steps required...

Thanks in advance

[Kevin_work]

Sfiso Myeni wrote:

> Hi
>
> May anyone please help me with this problem:-
>
> I've got a GPIB card initialised to be the system controller and a
> Rohde & Schwarz ESN Test Receiver that is a device in the ssytem.
>
> I find that after passing control to this receiver using the following
> commands, I fail to get it back to the GPIB card, as a result I end up
> having to manually reset the receiver by turning power OFF/ON.
>
> The commands that transfer control from the card to the receiver are:-
> These commands are sent using a Send(int addr,char * cmd) library function.
> Here I only give tou the command sent, but my program addresses the intended
>
> instrument.
> "*PCB 21" //tells the receiver where to return control later
> "*PCB 23" //23 is the receiver'
s address
> "LISTEN 21" //21 is the address of the GPIB card
> "TALK 23 TCT" //receiver takes control
>
> My problem is how do we tell the receiver to return control OR how does the
>
> receiver know when it is time to return control to the card and how does
> the card
> wait for this control to come back.
>
> I feel I'm missing a concept regarding setting up these system players to
> effect this.
> Could any one please take me through the steps required...
>
> Thanks in advance

There should be a command for the receiver to return control to the
GPIB card. I can not tell you what it is since I have never tried this and
I have no knowledge of the R&S device. I believe that the GPIB card will
wait for the device to relinquish control.

The main question I have is why you need to turn control over to the
device? I can only think of a couple of reasons and I think there are
other ways to accomplish this.

I would suggest you spend some time with the manual that came with the
GPIB card.


Kevin Kent