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Brill

It is good practise to not to daisy chain the 70V across each drive ie. use separate power leads from each drive to a common block and then connect the PS to the block. This ensures you are not getting a volt drop to each drive from the first one.

I'm going to engage pedant mode for a moment.
It's not to do with volt drop, it's mostly to do with the risk of harmonics.
Stepper drivers are essentially a complex switched mode power supply, which means they don't draw a constant current, they're constantly switching at high speed. If you place multiple of these on the same wire, then you risk harmonics, which is where multiple spikes at the same time lead to high voltage spikes, which can destroy electronics very quickly, and in extreme cases will burn out the wiring, even though the total current may be well within the current limit of the wiring.

Off course the latest drivers are far more likely to contain some internal filtering to help avoid noise being propagated into the supply, as part of them meeting various approvals, which should avoid any harmonic problems.

Avoiding daisy chaining also helps minimise any potential damage from a failed connection, as a connection failure during deceleration is very likely to result in an overvoltage failure, with resultant smoke release from drives. By having them wired direct, the worst case is one drive fails, but if daisy chained, you risk every drive after the bad connection failing.


Personally, I always wire drives directly to the main smoothing capacitor, as it avoids having any more connections in the wiring than needed.