Re: Advice on VME processor cards and OS for EPICS

[Michael Davidsaver <mdavidsaver@gmail.com>]

Hello David,

I'll echo Mark Rivers and encourage you to look at options other than VME.  IMO unless you're planning to deploy a number of crates I doubt VME will be the most cost effective solution (or anywhere close).  Hardware wise a decent crate + CPU card will be somewhere between 5-10k.  Software is similarly expensive, if not in monetary cost then in the time you'll invest.

My understanding of the present situation wrt. RTEMS vs. Linux is this.  RTEMS only supports a few VME CPU cards, all are powerpc.  While Linux will boot on many x86 based cpu cards the VME bus bridge driver situation is complicated.  There is an official linux vme driver, but it's interface design doesn't allow any existing epics drivers to use it (no mmio or interrupts in userspace).  There are a few bridge drivers floating around from various cpu card vendors which have been used, but since none are, to my knowledge, licensed for redistribution it's a bit difficult to know who is using what.

Of course this situation could be changed with some developer time, but I'm guessing this isn't what you're interested in :)

The closest I can point to for a "simple" solution is what I put together for NSLS2 (http://epics.nsls2.bnl.gov/debian/) which includes pre-built software support for RTEMS w/ mvme3100 cpu card (also mvme2100 and mvme5500).  That said I wouldn't recommend this for a new user as the mvme3100 is fairly old.  The newer mvme2700 isn't support for RTEMS (but is for Linux actually).

> https://www.acromag.com/catalog/840/embedded-computing-sbcs-fpgas/vme-sbc/intel-cpu

I hadn't realized that acromag sold vme cpu cards.  The xvme-6410 appears to have a common intel chipset and the tsi148 pci-to-vme bus bridge which is supported by the official linux driver.  RTEMS supports this bridge chip as well (it's also in the mvme3100), but getting RTEMS to work on a new board would require some developer effort.

Hope this helps,
Michael


On 11/05/2015 08:00 PM, David Vine wrote:
> Hi all,
> 
> I am looking to setup a VME crate and processor to run EPICS and synApps to control a STXM and handle data acquisition. Specifically I anticipate using a Struck multichannel scaler card (SIS3820) for data acquisition and OMS MAXv card for stepper motor control.
> 
> vxWorks is not an option due to price. Since I will be maintaining the OS myself and I am no expert I am looking for the simplest OS to set up and maintain and ideally with existing support for the abovementioned cards. I am comortable building EPICS and synApps on linux but I have no experience setting up a VME.
> 
> From my research I found two options and I'm hoping to get some advice on which option might be best:
> 
>  1. RTEMS. The RTEMS source builder seems straight forward to use but I'd appreciate if someone can recommend a processor, or advice on how to choose one?
>  2. RT linux. I don't really know if this would work but I could use an Intel processor from acromag (link below) and install linux and run EPICS on it. Is there a VME bus driver and would it support the cards I mentioned above?
> 
> https://www.acromag.com/catalog/840/embedded-computing-sbcs-fpgas/vme-sbc/intel-cpu
> 
> Thanks for your time!
> David