Re: USBTMC, Can't get device capability and Can't clear buffers

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Hi,

You are first getting the "Can't get device capabilities"  message, and then later the "Can't clear buffers" message. That is interesting because the code is this:

         if (getCapabilities(pdpvt, pasynUser) != asynSuccess) {
            libusb_close(pdpvt->handle);
            epicsSnprintf(pasynUser->errorMessage, pasynUser->errorMessageSize,
                    "Can't get device capabilities: %s", pasynUser->errorMessage);
            return asynError;
        }
         if (clearBuffers(pdpvt, pasynUser) != asynSuccess) {
            libusb_close(pdpvt->handle);
            epicsSnprintf(pasynUser->errorMessage, pasynUser->errorMessageSize,
                            "Can't clear buffers: %s", pasynUser->errorMessage);
            return asynError;
        }

Because it prints the "Can't clear buffers" message that means that getCapabilities() actually did succeed at least one time that it tried.  I suggest that you add some debugging printf() statements in getCapabilities() and clearBuffers() to see what arguments are being passed and what the error is.

The error messages also appear garbled or duplicated which may be a clue as to what is wrong.

Mark


From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of (대학원생) 문석호 (물리학과) via Tech-talk <tech-talk at aps.anl.gov>
Sent: Sunday, October 17, 2021 3:35 AM
To: tech-talk at aps.anl.gov
Subject: USBTMC, Can't get device capability and Can't clear buffers
  

Hello, 



I try to make epics control system for dg812(Rf signal generator of RIGOL).
The dg812 supported usb commuincation but the protocol is usbtmc so I used drvAsynusbtmc module of asyn. 
However, I faced  some error like below. 





I did the test in centos7 enviroment and the version of asyn is 4-26 and the version of base is 3.14.12.5 .
I also did the test with rasberrypi3 enviroment with same asyn and base version but it shows same error message. 

'Can clear buffer ~' and 'Can't get device capabilities ~'

The most strange thing is about usb mount. When I plug in the usb cable and check the usb mount at /dev, I can check that the usb is succesfully mounted with name 'usbtmc0'. 
However, after I run epics and see the above error, the usb is diconnected so I can't see the 'usbtmc0' at /dev directory.

 That thing happens at centos 7 environment and also in rasberrypi enviroment. 
Can you give me some advice about this error?

Best Regards 

SeokHoMoon




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Intense Beam and Accelerator Laboratory
Department of Physics
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50, UNIST-gil, Ulsan 44919, Republic of Korea


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Phone: +82-10-2767-9398

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