Can not communicate with the equipment

[jli]

Thanks for your post. What is "command-execution-complete byte"? Where can I find information about it??

[dong8]

hi,

In certain status byte specific to each instrument, there is one bit signifying if the command execution is completed. you need to poll this bit to insure no command sets in jam.

Perhaps in that LCR meter, RQS query is necessary before reading any data output. I would like to read those relevant pages in the manual. Scan it into files and post here.

But at first you need go thru the Write steps without error.

[jli]

Hi, Dong, Thank you so much. The write function now works well. The problem is in RQS. I am searching the operating manual to see if there is any help of the RQS. Thank you so much. BTW, are you in Europe?? I am in USA. Thanks

[jli]

The contents of RQS in Operating Manual are:

[dong8]

hi,

I read the document. Normally the bits in the status byte are noted as bit 0-7, but not definitely so.

So after receiving the commands, the LCR meter will process them and prepare the data for output, if no other error occurs. Meanwhile, it sets the status byte according to the actual situation. It is by analysing these enabled specific bits (i.e. bit 1,2,3,4) that you can understand the response of the meter to your command.

As you read, the state of RQS (bit 7) results from the OR operation on those four bits. So when RQS is set to ON, it signals that the meter is waiting for your intervention:

1. if data ready, you read out;
2. if error occurred, you need correct something;
or you can continue the next communication if the self test is completed.

see, RQS can be OFF when none of the four cases appears, so how can you wait for it? understand? only wait for RQS when be sure it can be set.

Even without RQS, you can always read the byte by serial polling it, using VISA "STB?" function. Normally you can set a loop to serial poll continuely the byte, like in waiting for the data or the completion of test. In every cycle, the useful bits should be analysed to determine if you can stop polling, and read the data or start to do other things.

Now the meter is under control if you can read its status. This is the whole of information.

After serial polled, the RQS bit may be reset by the meter. If not, you need reset it to OFF. The following service request will be initiated only when last one is cleared.

[jli]

Thank you so much for your help. I just replace the VISA RQS with 2 second time delay. And it works. No more errors. Thanks a lot.

[jli]

Thank you everybody who helped me. It is really a warm place to discuss with professional people. Thank you so much.

Have a nice weekend