I want my new control panel to be tidy and neat and for that reason I'm using DIN rails and cable ducts.

In addition, to bring the limits into the panel I plan to use one DB9 connector where all limits and home switches will be wired. So for a 4 axes machine I will have 2 pins for all limits, 2 pins for the Y Home, 2 pins for the A Home and 2 pins for a Touch Probe. Is this a good idea or it will be better to use separate DB9 connectors to avoid interference?

For the 4 stepper motors I can not decide if I will use 1 DB9 per 2 motors or 1 DB9 for each motor (my motors have 4 wires each). What is your suggestion?

Use 1 connector per motor, print your wiring convention, laminate it and stick it under the box.
If you ever have a motor, driver or other axis fault you'll bless yourself for giving you the opportunity to easily swap X, Y, Z or A  to Y, Z, A or X to identify the fault,  using 2 pins per motor connection will halve the connection resistance and halve the current through each pin which can never be a bad thing,
ATB,
Nick

I agree that you'll want to keep the wiring separate for each motor and each encoder. Those terminals you have are really to eliminate the need for plugging stuff in, and most commercial CNC machines just bring the cable right to the terminals. You then wire from the terminals to the various other internal destinations. I can say that I don't have a single connector for encoders or motors on my machine and it originally cost around $150k, so it wasn't to save money.

The cables just go through a strain relief into the controller cabinet (often in a bundle of cables), run through the cable ducts, then you pull the individual wires out through the sides of the ducts and connect them to terminals. That's how they are typically done for commercial applications.

I doubt the DB 9 connectors will be rated for the current the motors will pull. Might want to look at these.

http://www.pmdx.com/ConnectorsMisc

As mmoe said, any added connector is an added point for failure/problems.

May want to cut a big hole in your cabinet and maxke up a couple if wire tie strips. Put 2 pieces of foam in the middle and run the wires between the 2 pieces of foam. Something like the attached picture. Bend oin the red line, bolt to the cabinet in the large slots. Can use zip ties in the small slots........

Brett

Thank you all, very good info

What mmoe said sound the best and much easier for me and I do have strain relief connectors to get the cables thru the cabinet wall.

I noticed some companies selling pre wired control boxes for cnc and the limits / motors entering the box thru XLR connectors; I thought to do the same but since I have to order XLR's and I do have DB9, I thought it will be the same.

Anyway going straight to the DIN terminals will make for a nice control panel and avoid weak soldering joints