[etherlab-users] Distributed Clock with Yaskawa SGDV drives

[Henry Bausley]

The kernel module does contain the cyclic loop and it is always running.
The kernel module also has an ioctl interface so when the user space app
tells it to activate, the kernel module calls activate then sets some
flags so that the cyclic loop starts sending and receiving at its next
cycle.  In my case within 125usec - 500sec depending on the users setup.

On Fri, 2012-03-09 at 10:40 +1300, Graeme Foot wrote:
> Hi,
> 
> I'm not using any kernel side modules.  It sounds like what I'm doing is
> effectively the same, where there are two threads, one (hard rt) for the
> data cycle and the other to call ecrt_master_activate().  The cycle
> thread signals the ecrt_master_activate() thread when the master should
> be activated (on the very first cycle), whereas in your case your cycle
> thread is signalling to a kernel module instead.
> 
> Or is your kernel module doing the data cycle and the
> ecrt_master_activate() in one?
> 
> I'm being very conservative with my soft to hard transition delay
> (~50ms) to ensure I don't miss the first wakeup.
> 
> I also only enable the drive once in cyclic mode (and the drive has
> reached OP mode).
> 
> I've also replied to Florian with a bit more info.
> 
> Graeme.
> 
> 
> -----Original Message-----
> From: Henry Bausley [mailto:hbausley at deltatau.com] 
> Sent: Friday, 9 March 2012 08:58
> To: Graeme Foot
> Cc: etherlab-users at etherlab.org
> Subject: Re: [etherlab-users] Distributed Clock with Yaskawa SGDV drives
> 
> Graeme,
> 
>   I have always called ecrt_master_activate in my xenomai kernel driver.
> That same xenomai kernel driver has its cyclic loop running all the time
> but waits for a flag indicating whether to start ethercat activity.
> 
>   I trigger the kernel driver call to ecrt_master_activate with a user
> space application that makes an ioctl call to the xenomai kernel
> driver. 
> 
>   Using this methodology I don't have the "soft" to "hard" delay you
> describe and have not ever seen the errors you described with the SGDV.
> Also I always enable the drive when in cyclic mode ie. index 6040  =
> 0x80 -> 6 -> 7 -> 15 . 
> 
>  
>   
> 
> 
> On Thu, 2012-03-08 at 17:01 +0100, Florian Pose wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > 
> > Hi,
> > 
> > Am 23.02.2012 23:58, schrieb Graeme Foot:
> > > I configure my amps to use cyclic position mode which requires the
> > > pdo data to arrive consistently.  In the time it takes to go from
> > > soft to hard rt the amps often miss too many pdo datagrams and they
> > > were raising the alarm A12 (Sync Error).
> > 
> > ecrt_master_activate() is intended to be called when no slaves are
> > operational and there is no necessarity to have any meaningful
> > operation anyway. Why are your slaves complaining when they are not in
> > operation yet? They should checks for sync errors earliest when in
> > SAFEOP state.
> > 
> > - --
> > Regards,
> > Florian
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> 
> 
> 
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