Hi there,
For a future project we are making a first study, and as I'm not really familiar with NI solutions, I hope some of you can share some thoughts.
For this project, we will have to control the following hardware:
- 28 cryogenic stepper motors in open loop (no encoder feedback possible) and very simple motions ("move x degrees") just a few times per hour max.
- 2 cryogenic stepper motors in open loop, but with a constantly changing position setpoint (>50Hz should be fine)
- 50-100 I/O temperature and pressure readings (sampling in de range of a few Hz maximum)
How would a possible "NI solution" look?
Our systems engineering guidelines say that it is highly preferrably to move the "control unit" away from the instrument (say 50 meters apart, in a computer room), and that all fieldbuses should be ethernet based. In that case I was thinking to have:
- a PXI chassis in the computer room
- an EtherCAT connection from the PXI chassis to a daisy chain of 4 NI-9144 expansion chassis, all equipped with the 28+2 NI 9512 stepper controllers, connected to 28+2 stepper drivers
- an extra NI-9144 (or compactFieldpoint chassis) for the DAQ
It seems quite rediculous to have so many NI-9144 expansion chassis, so another solution is to ignore the "control unit near instrument" rule and to have a single PXI controller with 4 8-axis stepper controller boards and a few DAQ boards inside.
Another solution would be to have 28+2 standalone third-party stepper "controller and drivers" inside the instrument, connected with an ethernet fieldbus to a labview target in the computer room. But I'm having troubles of finding suitable stepper controllers+drivers (maybe because stepper motors and ethernet motion control are not so commonly found in industry?)
Thanks for any thoughts on this,
Wim
