Re: EPICS support for Fastech motors

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Hi Rea,

•  I see that driver developers prefer to use octet-based communication rather than use the manufacturer-provided libraries. Is there a reason why that is the case, or is it simply that octet-based communicaton is more universal?

Manufacturer libraries will be provided for specific operating system and specific versions of those OS. That can restrict where they can be deployed.  They may restrict redistribution, which prevents including them in the motor Github repository.  They almost certainly won't be supported on real-time OS like RTEMS or vxWorks.

• Further, the Fastech controller allows both octet-based communication and library-based communication, but octet-based communication requires the master to send a one-byte "sync number" which serves as an idempotence token. I assume it would be necessary to implement that myself; could I be using some sort of global variable, and how do I make sure that I never land on the same number twice in a row?

Many protocols have something like that.  You just have a member variable in your driver class that increments by 1 on each message it sends, and wraps back to 0 after 255.

Mark

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From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Rea Domitrović via Tech-talk <tech-talk at aps.anl.gov>
Sent: Wednesday, June 17, 2026 8:34 AM
To: Torsten Bögershausen <tboegi at edom.se>; tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Re: EPICS support for Fastech motors

Hi Torsten,

thanks for pointing me in the right direction. I'm looking at the manual and the source for other submodules now (motorSmarAct and motorAcs); I see that driver developers prefer to use octet-based communication rather than use the manufacturer-provided libraries. Is there a reason why that is the case, or is it simply that octet-based communicaton is more universal?

Further, the Fastech controller allows both octet-based communication and library-based communication, but octet-based communication requires the master to send a one-byte "sync number" which serves as an idempotence token. I assume it would be necessary to implement that myself; could I be using some sort of global variable, and how do I make sure that I never land on the same number twice in a row? Kind regards,

Rea

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From: Torsten Bögershausen <tboegi at edom.se>
Sent: Wednesday, June 10, 2026 1:49:41 PM
To: Rea Domitrović; tech-talk at aps.anl.gov
Subject: Re: EPICS support for Fastech motors

 

Hej Rea,

I haven't worked with them, no.
If you have Ethernet (not to be confused with EtherCAT),
I read the manual as if they use UDP for communication,
and knowing that you can write a simple model 3 driver, I think.
(Other suggestions are welcome of course)
/Torsten


On 2026-06-10 12:52, Rea Domitrović via Tech-talk wrote:
> Hi all,
>
>
> I'm working with some Fastech Ezi-Servo II Plus-E motors, and I was
> wondering if someone had already worked with them and/or made an EPICS
> driver or Motor submodule? This particular line of motors and
> drives uses an Ethernet interface. Kind regards,
>
>
> Rea Domitrović
>
> Institut Ruđer Bošković
>
> Zagreb, Croatia
>

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