Re: Same device on multiple IOCs

[Ralph Lange via Tech-talk <tech-talk at aps.anl.gov>]

On Mon, 5 Oct 2026 at 12:56, Rea Domitrović <rea.domitrovic at irb.hr> wrote:

The multiplexer is a piece of hardware, using StreamDevice support over TCP for control.

> Why do you want to multiplex in the first place, instead of having a separate Asyn port for each accelerator?

Because on each accelerator we have two Faraday cups (4 total) whose signals are multiplexed into one picometer per accelerator. This is a limitation of the fact we have one physical multiplexer (with two multiplex cards) and only two picometers. To avoid multiplexing we would need to have four picometers.

Ok, that makes a lot of sense now.

Here's a general design idea - one of many possibilities, just to show how a typical EPICS database design could look like

Two low level records for controlling the two mux channels (probably mbbo = enum type).

Two low-level input records (ai) that read the picometer data.

Two dfanout records (one for each low-level input) to demultiplex the data inside the EPICS database into...

Four high-level input records (ai), one for each accelerator.

Two combinations of calcout and seq record that automate the setup: The calcout is creating bit patterns for the seq, and the seq (in bitset mode) does the sequencing: put the dfanout in idle, switch the mux box, wait a bit, put the dfanout to the right high-level input.

If you want automation, have the calcout flip back and forth.

Like Lego pieces that can do interesting things when put together correctly.

Cheers,
~Ralph