Thanks for the info.
What is your overall time frame: 2015, 2016 ?
And some more questions/comments inline.
On 2015-07-14 17.20, Mark Davis wrote:
> Hi Mark,
>
> As is probably true with most labs, we do indeed have some VME stuff, but for
> the main control system we have been slowly eliminating VME when we can. The
> hardware is just so much more expensive than using fairly generic rack-mount PCs
> running Linux and using Ethernet (directly or via
> Ethernet-to-serial/GPIB/whatever adapters) to talk to stand-alone devices.
>
> So far the list of requirements I have compiled from searching through the mass
> of documents regarding the new FRIB infrastructure has not turned up anything
> particularly demanding, but of course many details are still in flux so I am
> trying to be "generous" in terms of reading between the lines and extrapolating
> a bit regarding what is likely to be required once the details start firming
> up. As long as some particular feature doesn't result in a drastic increase in
> price, a solution that does a bit more than meet the minimum requirements will
> undoubtedly save us money in the long run.
>
> This is what I have come up with so far that is related to the choice of
> controller:
>
> - Complex coordinated motion (2 axes minimum for insuring smooth movement of
> things like pairs of jaws)
> - Fault outputs (so an external PLCs can manage the state of a group of
> related devices)
(I'm just curious to collect and steel ideas from other people),
What should the PLC do exactly?
Some kind of supervision, machine protection, personal protection ?
> - Support for 3 limit switches (min, max, and home/reference positions)
OK
> - Support for on-the-fly scans:
> - At minimum, the ability to generate pulses for each axis based on
> current position of each axis
> - Ability to capture/buffer the data itself would be a plus
> - Support for a variety of analog or digital encoders. Currently specified
> types include:
> - Linear motion potentiometers
Do you mean an "analog input", which is converted into a position ?
> - Rotary Sine/Cosine potentiometers
> - Digital (optical, rotary, relative, absolute?)
Any more ideas about the encoders as such ?
> - Support for local control box (i.e. continue to track/report position,
> disable movement if limit switch activated, etc)
What should the "control box" do ?
Is it an EPICS IOC ?
Doesn't the motion controller stop the motion, when a limit switch is hit ?
Do you want support for soft limits ?
> - Prefer models that do not require external motor drivers
> - Ethernet interface
> - Firmware version readable by control system
Which control system ?
EPICS ? Something else ?
> - Ability to update firmware remotely
That should be OK for all Ethernet based controllers
(Please correct me if that is wrong)
Do you have anything special in mind ?
>
> Regarding closed loop mode: While I can imagine circumstances where you might
> want to disable it, I would think that any controller that supports an encoder
> would also provide a closed loop mode. Is that not so? I would think there
> would be little advantage to supporting an encoder if it couldn't be used
> directly by the controller during movements (i.e. isn't this question the SAME
> as "Does it support a position encoder"?)
I think so.
Some controllers should be able to make "smooth movements" towards the
target position.
>
> Regarding price/axis: I haven been given a specific $ amount on this yet, but
> we have been using the Parker GT6K single-axis controllers which are around
> $3000 each, and I have been assuming that most newer multi-axis solutions will
> be significantly less expensive.
How many axes in total are you thinking of ?
How much man hours for SW development are you willing to spent ?
>
> Mark
Before going into too many details, what is your idea about controlling the
axes via EPICS ?
[snip]
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