- the solenoids, each with its oun preset metering valve, are simply switched on and off via a relay card in a scanner controlled via GPIB
- the adjustable metering valve is the other way to do the same thing but using the 4-20mA output of a flow meter and a PID controller set up in software (LabVIEW) to then adjust the valve to the particular setpoint, in terms of flow
- there are numerous scanner cards, which can be for current, voltage, TCs, RTDs, AC for the solenoids, etc.; each of which is connected to the appropriate instrument, which provides the datum back via GPIB to LabVIEW
I'm not so concerned about input and output types, unless something requires a variable resistance input
-> for this Groth is building me a 'digital pot' with a LabVIEW vi, a bit of a chore but coming along
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