Experimental Physics and
Industrial Control System

"Peterson, Kevin M. via Tech-talk" <[email protected]> · Thu, 24 Oct 2019 17:07:58 +0000

Lee,

If the default asynMotorPoller() is used, the frequency at which the 
poll() methods get called can vary, since the idle poll period is not 
necessarily equal to the moving poll period.  It looks like the call to 
pcsControllerConfig sets both poll periods to the same value, so maybe 
that hasn't been a problem.

If you create a dedicated poller thread to read the UDP stream, that 
polling frequency can be independent of the pcsControllerConfig poll 
periods.  This is a common approach is used areaDetector drivers.  One 
example of these poller threads is pointGrey's imageGrabTask():

https://github.com/areaDetector/ADPointGrey/blob/9dda1cf68ec0757c64154144f197536d6a37622d/pointGreyApp/src/pointGrey.cpp#L880

It is likely you can make it work by reading the UDP stream in the poll 
function, but I think a dedicated poller thread is a better solution.

Kevin

On 10/24/19 5:19 AM, Lee Hudson via Tech-talk wrote:
> Hi,
> 
> I'm currently writing a motor driver and I'm not sure on the best way to 
> implement a particular aspect of it. The main control link to the 
> hardware is via TCP/IP, on startup the driver registers parameters of 
> interest on the controller and the controller then sends all subscribed 
> information out via UDP broadcasts. I think I need to create a udp 
> server on the IOC, so far I am doing the following:
> 
> *IOC boot script:*
> 
> #TCP port for control, this works
> 
> drvAsynIPPortConfigure("PCS1_CTRL", "192.168.113.10:51512", 100, 0, 0)
> asynOctetSetInputEos("PCS1_CTRL", 0, "\r\n")
> asynOctetSetOutputEos("PCS1_CTRL", 0, "\r\n")
> 
> # Configure UDP port for Walter and Bai streams
> drvAsynIPServerPortConfigure(PCS1_UDP,"192.168.113.12:51513 udp", 10, 0, 
> 0, 0)
> # Configure Walter and Bai PCS8000 controller
> pcsControllerConfig(PCS1, 0, 2, 20, 20)
> 
> # Configure Walter and Bai PCS8000 Axis
> pcsAxisConfig(PCS1, 1)
> 
> # Configure Walter and Bai PCS8000 Axis
> pcsAxisConfig(PCS1, 2)
> 
> 
> *Driver constructor(**class pcsController: public asynMotorController ):*
> 
>      /* Connect to pcsController controller TCP for control */
>      status = pasynOctetSyncIO->connect(lowLevelPortName, 0, 
> &pasynUserController_, NULL);*
> *
> 
> *
> *
> 
>      pasynUserUDPStream = pasynManager->createAsynUser(0,0);
>      status = pasynManager->connectDevice(pasynUserUDPStream, 
> streamPortName,0);
>      pasynInterface = pasynManager->findInterface(pasynUserUDPStream, 
> asynOctetType, 1);*
> *
> 
>      pasynOctet = (asynOctet *) pasynInterface->pinterface;
>      octetPvt=pasynInterface->drvPvt;
> 
> 
> *Driver poll():*
> 
> status = pasynOctet->read(octetPvt, pasynUserUDPStream, rxBuffer, 65535 - 1,
>                                &nBytesIn, &eomReason);
> 
> 
> In the poll() method or perhaps a separate thread elsewhere I know I 
> will have to update the asyn parameters manually and call 
> callParamCallbacks() to get the record to update. Am I going about this 
> the right way?
> 
> Thanks in advance
> 
> Lee
> 
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System