VxWorks to XPE

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I am Interested for an answear to Andy Izsaks question on the real time performanse of XPe. I know XPe is not as real time as Windows CE and VxWorks, but to what extend. Can I use it for Industrial controls applications that needs a deterministic response within half a second (500 ms).
 
Come on, you call 500ms real time?

From user mode no one can give guaranties to you that this can be done. But
if you remove all services, don't have HDD, etc and you app is set for real
time priority.
Then you can confident that this will work (although no 100% guaranties).

If you write driver (program in kernel mode) then you can set your work
thread priority so high that is will preempt everything else in the system.
In this case is your system does not hang, and you don't have some other
unusual drivers, you probably can achieve response on system time tick
precision that is less than 20 ms.

And you always have option to use some hardware timer interrupt source for
absolute precision.

As with all other XPe projects you need to make sure that this is possible.

Regards,
Slobodan

JohnO said:
I am Interested for an answear to Andy Izsaks question on the real time
Click to expand...
performanse of XPe. I know XPe is not as real time as Windows CE and
VxWorks, but to what extend. Can I use it for Industrial controls
applications that needs a deterministic response within half a second (500
ms).
 
I suggest Windows CE for you project windows XPE will not cut it.
JohnO said:
I am Interested for an answear to Andy Izsaks question on the real time
Click to expand...
performanse of XPe. I know XPe is not as real time as Windows CE and
VxWorks, but to what extend. Can I use it for Industrial controls
applications that needs a deterministic response within half a second (500
ms).
 
JohnO said:
I am Interested for an answear to Andy Izsaks question on the real time
Click to expand...
performanse of XPe. I know XPe is not as real time as Windows CE and
VxWorks, but to what extend. Can I use it for Industrial controls
applications that needs a deterministic response within half a second (500
ms).


I am using XPE in an Industrial Control application with response times
required of much less than 500 msec. So far it has been highly successful.
Of course it always depends on what you mean by "deterministic", the amount
of variance you can tolerate, and what happens if you are late. In my case,
the workcell is pretty much in a lock-step sequence controlled by a PLC. If
our system is less responsive for some reason, the cycle time of the cell
increases. This would be a cause for great bitching (not uncommon in GM
plants), but would not be damaging or unsafe in any way. We are forced for
various reasons to poll for commands from the PLC on a DeviceNet interface
(and don't want to do this in a tight loop!), but are currently responding
to commands within 10 msec nominal.

Overall we are highly satisfied with the use of XPE, and especially how easy
it was to configure the system and port an existing application that
previously ran on DOS and Windows 95 to the XPE platform.

Doug G
 
I for one do not need actual hard real time performance.
I'm looking for 30ms system wide response (node to node) and that can be
done with standard xp.
I simply want to see who esle may have made the move and on what type of
projects.


A<.
 
Come on, you call 500ms real time?
Click to expand...

The classical definition of real time does not require a low response time,
only that responses to events are deterministically bounded in value.
Accordingly, a system with a 500ms response time can indeed be a real time
system.
 
I know exactly what real time means.
I have programmed devices that must process 32 inputs and outputs at 0.1 mS
(exactly at 1600 oscillator clocks ) without any jitter acceptable this is
what I call hard real time.

And if question was if this can be done in 50 ms on Windows XPE then I would
think about this before saying yes.
But since requirement is 500 ms only chance that XPe wont be able to handle
this (every time) is if you make extremely bad XPe configuration and real
time program on very low priority.

It is always up to you. But if you consider using program written at driver
level you can accomplish this without any worry.

On windows you will have time jitter that you can't predict but if it is
acceptable for you to respond to some event within 1ms time it is possible
is most of cases (depending on drivers you use in your image).

Regards,
Slobodan

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