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Forum Topic - ClockAdjust effect on timer: (1 Item)
   
ClockAdjust effect on timer  
Hi there,

I'm trying to compensate the clockdrift between two PCs (VxWorks and QNX) with ClockAdjust. On the QNX site I use a 
timer to let the system do something every 4 ms. Those 4 ms have to be exactly the 4 ms I measure on VxWorks site. So in
 my system I adjust the clock under QNX with ClockAdjust().

What I experienced is that ClockAdjust seem to have no effect an the time. I wrote a small test program (without the 
VxWorks site) that gets a time-event every 0.5 s. And after the timer-event I adjust the clock in 2000 ticks by 12500 
nsec every tick (CLOCK_RESOLUTION = 125000 nsecs). So in the the end on the console I get the expected 525000000 nsecs 
as the interval. But when I measure the real time by signaling the parallel port and using an oscilloscope I only get 
the exact 500 ms between timer events.

What exactly happens when I create a timer and when does it run out? By what I am experiencing I guess, on creation the 
number of ticks until end of time is calulated and then a counter is increased every tick until number of ticks. If this
 is so... How can I adjust the time and also affect the timer. So what I want is 475 ms in real time every timer-event.

cheers,
  Alex