Is a reliable interaction between LabVIEW Client and GreenMode.Asyncio DS possible?

Development Labview
1

Hi everyone, I am wondering if it is possible to work from LabVIEW client with a GreenMode.Asyncio DS? I simply update a scalar double DS attribute from a VI. When DS Asyncio mode is used, after some times writing I get the error:

Error -1 occurred at tango.lvlib:_TangoExceptionToLabviewError.vi

Possible reason(s):

[TangoWriteAttributes.vi]  - ERROR - API_CorbaException - TRANSIENT CORBA system exception: TRANSIENT_CallTimedout - DeviceProxy:write_attributes - ERROR - API_DeviceTimedOut - Timeout (3000 mS) exceeded on device test/lvproxy/1 - DeviceProxy:write_attributes
Complete call chain:
     tango.lvlib:_TangoExceptionToLabviewError.vi
     tango.lvlib:_TangoWriteAttributes.vi
     tango.lvlib:_TangoWriteDoubleScalarAttribute.vi
     Sinus Generator.vi

No problem, if I don’t use Asyncio or hide it behind a synchronios interface.

2

Hi ALex,
Can you confirm that your pyTango device behaves properly with another client?
E.g. a simple pyTango one or even Jive.

3

Hello Nicolas,
No, i can not…
Here is the test DS:


class LVProxyAsync(Device):
    green_mode = GreenMode.Asyncio

    async def init_device(self):
        super().init_device()
        self._sinus_signal=float('nan')
        self._saw_signal = float('nan')
        self.set_change_event('sinus_signal', True, False)
        self.set_change_event('saw_signal', True, False)
        self.set_state(DevState.RUNNING)
        self._values={}

    @attribute(dtype=float)
    async def sinus_signal(self):
        return self._sinus_signal

    @sinus_signal.write
    async def set_sinus_signal(self, nValue):
        self.debug_stream(f"Write Sinus: {nValue}")
        self._sinus_signal = nValue
        self.push_change_event("sinus_signal", nValue, time.time() , q.ATTR_VALID)

    @attribute(dtype=float)
    async def saw_signal(self):
        return self._saw_signal

    @saw_signal.write
    async def set_saw_signal(self, nValue):
        self._saw_signal=nValue
        self.push_change_event("saw_signal", nValue, time.time() , q.ATTR_VALID)

Here is the test code:

from tango.asyncio import DeviceProxy as aDS
import numpy, asyncio, tango

lvproxy_async = await aDS("lvproxyasync/lvproxyasync/1")
for i in range(100):
    try:
        await lvproxy_async.write_attribute("sinus_signal", numpy.sin(i))
        await lvproxy_async.write_attribute("sinus_signal", numpy.sin(i))
        await asyncio.sleep(0.1)
    except:
        print(f"Error after {i} try")
        break

I think more easier is not possible… I will ask pyTango community.

4

Yes, please ask the pyTango experts what they think about the problem and let see what I could do to help.

5

OK, here come some confusing details…
I have assumed that my Windows setup is again the problem. So I have moved the DS to Ubuntu VM where my Tango config DB also lives.
But at the end Jive-ATK-monitor panels seems to be causing the problem. It’s like Schrödinger’s cat: alive as long as you don’t look at it. As soon as you start ATK Monitor, errors come up.

6

Ok. Can you please validate the implementation of your python device with the experts? Just to be sure that it’s not the root cause of your problem. The reported error is a timeout that tends to reveal a response time problem on server side. The fact that you also observe the problem with Jive reinforce the idea of a problem in the server behavior. You don’t think I can help you more. I simply invite you to post on the Python dev forum.