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Subject: Re: Multiple IOC's in a crate?
From: Andrew Johnson <[email protected]>
To: W T Meyer <[email protected]>
Cc: [email protected]
Date: Tue, 09 Nov 2004 18:38:41 -0600
W T Meyer wrote:
Is it possible to run two or more IOCs in a single VME crate? At present we're running MVV-177 IOCs running VxWorks, but are considering upgrading.

It is, providing you're careful.


If you have any device or driver support that does autodiscovery you need to make sure that only one IOC loads this code - you don't want both CPUs trying to control the same hardware. Many of the older support routines look at specific addresses for their hardware, and these are the ones you'd probably need to restrict to just one IOC.

As Larry mentioned, you also need to partition the VME interrupt levels between the CPUs so there's no overlap - each interrupt level must be enabled [by calling sysIntEnable()] on at most one CPU. Again, some of the older standard device support routines may enable specific levels without being explicitly initialised, so you can't load these on more than one IOC.

I'm not sure whether the one dual-IOC crate we had here at APS is still in that state, but we certainly have used that approach here in the past.

- Andrew
--
Dear God, I didn't think orange went with purple until I saw
the sunset you made last night.  That was really cool. - Caro


Replies:
Re: Multiple IOC's in a crate? Maren Purves
References:
Multiple IOC's in a crate? W T Meyer

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