Breakout Board Speed Control

I would think something like this would work, right? It has a PC817C, so I figure it is used to optically isolate the two circuits. What has me slightly concerned is that the listing (and many others) don't mention the fact that they are optically isolated (does this mean that it isn't?).

Logthor wrote:

this would work, right? 

Yes, this is a very similar circuit to the one used in BOB and will work identically.
The difference is that the power supply for this circuit should be not used for anything else, that BOB does not provide.
Voltage is a potential difference and is measured between two points.
The same wire, it may be 12V to the second pole of the power supply, but hundreds of volts to machine chassis.

Makes sense. So I need a separate power supply for this converter? Here is the documentation for my KDIC unit. I'm still a little unsure of what the danger is. I still would like an explanation as to why my HAL file isn't working.

Logthor wrote:

So I need a separate power supply for this converter? 

If a device is not isolated from the power grid, it may cause fatal shock, damage to the electronics or its incorrect operation.
What's worse, it all depends on which wire you connect where.
The machine can operate safely and without failure for years, and when connected to another wall socket, it may burn itself or kill the operator.
To prevent this from happening, all you need to do is spend a few dollars more on an already expensive machine.
I really don't know what to discuss here...

Alright, fair enough. I've already purchased a separate supply and a PWM to analog converter. I'll just use the pot on the board to make it send out a max of 7 volts and use the basic stepconf to set up the spindle RPM.

I am doing this like I said, but I am still quite confused on how this could pose a shock hazard. It doesn't matter if the e-stop, homing switches, etc. are connected to the spindle control circuit if it is optically isolated between the KBIC and break out board. I just don't see how buying a separate supply and separate PWM to 0-10V analog unit is going to make it any safer.

Logthor wrote:

I am doing this like I said, but I am still quite confused on how this could pose a shock hazard. It doesn't matter if the e-stop, homing switches, etc. are connected to the spindle control circuit if it is optically isolated between the KBIC and break out board. I just don't see how buying a separate supply and separate PWM to 0-10V analog unit is going to make it any safer.
 

For electric current to flow, two conditions must be met - there must be a potential difference (voltage) and a closed circuit. Until you close the circuit (e.g. by touching the controller and some ground with your body at the same time) you will not be aware that there is dangerous voltage there. Current may flow, for example, from the controller terminal's power grid, through the controller input to the 0-10V board, from there to the 12V power supply, through the power supply to the homing limit switch, through the limit switch and your body to the housing of the device grounded to the other pole of the power grid. Believe me, there will be voltage and a closed circuit...

Current may flow, for example, from the controller terminal's power grid, through the controller input to the 0-10V board, from there to the 12V power supply, through the power supply to the homing limit switch, through the limit switch and your body to the housing of the device grounded to the other pole of the power grid. Believe me, there will be voltage and a closed circuit...

Yes, but there is an optocoupler between the KBIC and BoB I'm not sure where the danger is. Assuming that the optocoupler is functioning as it should mains shouldn't even reach the BoB.

For posterity's sake, I ended up buying an SI-5 isolator board for my KBIC-240ds. I bought two PWM-to-analog converters, and both featured no optical isolation between all grounds. If you want true isolation (which you need for the KBIC-240ds), it seems that you need to buy this separate component or some sort of dedicated device that gives you galvanic isolation. My spindle seems to be working quite well currently.