I am in EU, and I am quite interested in your kit!
(late edit: I shall read the links in your above post #17)
what I have to decide - I hope with your help - is, if there is and what would be a configuration suitable for my case!
perhaps you can provide me with an contact address/link, for posting some more details, as I am afraid my request does not fit your firmware... perhaps I don't even need the firmware...
however, trying to be short:
it is about a modified Strega: I use a PID for controlling group temperature (effective mostly in idle), a pressure gauge conveniently connected after the check valve and the ULKA EX5 pump, and a standard light/fan switchable dimmer to control the average flowrate of the pump;
you know, the Strega is using the pump for filling the cylinder chamber via an heat exchanger: with a stock machine, there are 5 sec of 0 bar chamber filling (at maximum pump flow rate of more than 10 ml/sec), then the pressure starts to build up, the flowrate is diminishing and somewhere on the pressure ramp (to 10 bar) the puck will became saturated and the extraction will start to flow into the cup;
at this very moment of the preinfusion ending, the lever is usually raised, manually, 'on the springs' and the extraction continues under the pressure of the springs;
as soon as the lever is leaving its lower resting position (piston is coming down), a microswitch disconnects the pump and from now on the process is fully manual/mechanical;
the preinfusion lasts usually during the pump run, and it is this phase of the shot only, when I need the right control of the pump flow; it could be a manual control, with a knob, or also a programmatic one;
for using this phase of the process to profile the preinfusion, your way of controlling the pump seems the best!
however, I wonder if you have any pressure-flowrate chart for different settings in controlling the pump?
would it be possible with a vibratory pump to have a complete pressure ramp up to 10 bar (the pressure exerted by the springs after), but with a slower flow, which would make this ramp much longer?
with a standard dimmer in its lower setting, in my case, the pump runs slowly, reaching a maximum of 1-1,5 bar in the chamber, in more then 25 sec; and the pump 'dies' - zero flow;
this means a lower volume of water into the chamber and a lower starting pressure for the springs; it would be better of course to be able to experiment further...
also I would like to use both PID functions, for the group and for the boiler too; and the better sensor and sampling provided;
I wouldn't like to use a dedicated screen if all display functionality could be transferred remotely to a laptop; but I presume it is possible to record all the real time charts, having kind of a data logger functionality?
I saw you have a deadline on Dec 7, so I would like to make an order before...
thank you sandc, for all the information!