7i76E Power Source & Estop

I am planning to rewire my machine from parallel ports/BOBs to a 7i76E. It is a simple 3 axis 4 joint gantry with a router as the spindle.
My current machine uses the 5V and 12V from the PC for logic and field power. The Estop button NC contact interrupts power to the stepper supply and the router speed controller. The NO contact is connected to estop-ext. The logic and field I/O are powered whenever the PC is on.

Based on the wiring diagram I found on the forum (7i76_Anschluss_2017-01-02) I was planning to use a single 24V 5A supply for board and field I/O power. Then I read some posts about EMI and other subjects that mentioned using a separate 5V supply for the board. I found no discussion about the pros and cons of the two approaches.

I am also planning to continue my current approach of interrupting the spindle and stepper AC power via the Estop button independent of LinuxCNC and leaving the board and field power source(s) enabled. The LinuxCNC Estop configuration is a question for another day.

What are the advantages or disadvantages of the options for powering the Mesa board and field I/O? Is there a significant advantage in using separate 5V and field power supplies and separating their grounds?

John

You probably only need the 5 volt power supply if you have additional boards connected to the expansion connectors and you need more current than the 7i76e can supply.

24 volt field power is recommended for best noise immunity but 12 volt will work. You probably only need a 2 amp power supply.

You need the 7i76e to be powered up or you cannot connect via ethernet so Linuxcnc will not start.

Estop just needs to disable all motion so your approach is fine and how I did my 7i76e. One side of the switch is mains power, the other side switches field power to an input on the 7i76e.

Also search the forum for "My 7i76e Connection shet" to find Norberts amazing siring diagram for the 7i76e.

If you do use the MPG inputs, you need to tie the 12v and 24v grounds together so there is probably no point worrying about keeping the grounds isolated.