[mvoltin]

Hi,
I am building the first CNC with a BOB found here: http://wiki.midsouthmakers.org/image...axisManual.pdf and have a general question to better understand the principle for operation:

BOB basically allows to connect to motor drivers via step/dir/enable pins (along with limits, etc.). Why are there additional pins to stepper controllers (white connectors behind the green step/dir/enable bins)? what the purpose of these?

Also, why is there a 24V power supply connection (in addition to 5v)? 5v should be sufficient for step/dir/enable signals and the 24v should connect directly to stepper controllers, right? Same question about the relay: what does it do since there is no power output to stepper motor drivers (assuming the relay controls the power to the drivers).

and what is the output to the frequency converter for?

I know these are very newbe questions but I have been researching this for a while and still came up empty handed. Here is related posts but they do not provide response to my questions:

http://www.cnczone.com/forums/mach-s...l-mach-v1.html

Thanks.

[ger21]

BOB basically allows to connect to motor drivers via step/dir/enable pins (along with limits, etc.). Why are there additional pins to stepper controllers (white connectors behind the green step/dir/enable bins)? what the purpose of these?

The white connectors are the same as the screw terminals, and allow you to use plugs instead of the screws. You'd use either the white plugs or the green screw terminals, but not both.

Also, why is there a 24V power supply connection (in addition to 5v)? 5v should be sufficient for step/dir/enable signals and the 24v should connect directly to stepper controllers, right?

The board designer probably chose 24V to allow the use of the motor power supply to power the breakout board. It's actually 12V-24V.


The relay can be used to turn the spindle on and off, or turn some other device on/off.

and what is the output to the frequency converter for?

You can use it to control the spindle speed, if your spindle speed controller supports it.

[mvoltin]

thank you, Garry. Really appreciate