EPICS is fast, but 0.1 second is perhaps too demanding. Try increasing the
time interval to 1.0 and see if that fixes the problem, and then reduce it
to see how fast you can go. If you want to write the fastest possible
program, you will need to use the callback style. In any case, don't
use too small a time value in send() or you risk failure (unless you
put the pend into a loop).
The sys.pend(fd) style of call is mostly intended for internal use, and should
not generally be used by application programmers, so make sure
you always pass a float, not an int. (This ambiguity may be removed
in a future version of CDEV).
Chip
Miroslaw Dach wrote:
> Hi,
>
> I am just a beginner in CDEV. I wrote my first program in C++
> using CDVE to communicate with the EPICS server. When I use synchronous
> send command to read one datum from the EPICS server using Channel Access
> service all was fine. Unfortunately I do not know why it does not work
> for asynchronous send (i.e. sendNoBlock ). Actually when I use
> sys.pend(fd) ( to flush all pending output )
> with the "fd" argument set to any number it does work. If the
> argument fd is not specified it does not work.
>
> Does anyone have an idea what could be wrong?
>
> Bellow there is a source of my small program:
> //-------------------------------------------------------
> /* $Id$ */
>
> #include "cdevSystem.h"
> #include "cdevDevice.h"
> #include "cdevData.h"
> #include <sys/types.h>
> #include <sys/timeb.h>
> #include <stdio.h>
> #include <stdlib.h>
>
> void main(int argc, char **argv) {
>
> cdevData result;
>
> cdevSystem &sys = cdevSystem::defaultSystem();
> cdevDevice &mydev = cdevDevice::attachRef("magnet13");
>
> if(mydev.sendNoBlock("get VAL",NULL,result)!=CDEV_SUCCESS){
> puts("sendNoBlock failed");
> exit(0);
> }
>
> sys.pend(0.1);
>
> result.asciiDump();
>
> }
>
> //--------------------------------------------------------------
>
> Regards
>
> Miroslaw Dach