[fastbike]

I'm looking for confirmation that my understand of the ALM output in the CL86T driver from OMC Stepper Online is correct.

The documentation states that the ALM signal

Fault Signal: An OC output signal which is active when one of the following error protection is
activated: over-voltage, over-current, and position following error. This port can sink or
source 20mA current at 5-24V. The resistance between ALM+ and ALM- is low impedance in
normal operation, and will change to high when the drive goes into error protection. The
voltage active level of this fault output signal can be configured by configuration software.

Given my CNC controller (Eding CNC720) has a a motor fault input with an internal 2k7 pullup resistor, do I run the ALM outputs from the X-Y-Z drivers in series, so that normally all 3 driver open collector outputs will be closed. So the CNC controller will normally see 0v (i.e. GND) and if any of the drivers fault, then the series circuit will be broken, and the pull up resistor will take the signal high.

I'll try to post a schematic later.

[dazp1976]

I'm looking for confirmation that my understand of the ALM output in the CL86T driver from OMC Stepper Online is correct.
The documentation states that the ALM signal
Given my CNC controller (Eding CNC720) has a a motor fault input with an internal 2k7 pullup resistor, do I run the ALM outputs from the X-Y-Z drivers in series, so that normally all 3 driver open collector outputs will be closed. So the CNC controller will normally see 0v (i.e. GND) and if any of the drivers fault, then the series circuit will be broken, and the pull up resistor will take the signal high.
I'll try to post a schematic later.

Almost. Depends how the drive or controller in question works. Not all are the same.
Normally:
1. If your drives are closed when there's no alarm condition then yes you would wire them in series.
There should be voltage running permanently through this circuit under normal condition.
When alarm opens one of them, the circuit is broken, voltage is dropped to 0v, controller then triggered.


2. If your drives are open when there's no alarm condition then you would wire them in parallel.
This time there should be 0v running permanently through this circuit under normal condition.
When alarm closes one of them, the circuit is made, voltage is applied, controller then triggered.


Joining of limit switches works in exactly the same way.
NC , Statement 1.
NO , Statement 2.


Not familiar with your controller type though. Are you using a breakout board or connecting direct?.
Directly. Your controller looks to be designed for NO switches. NO can't be wired in series.
Drives need ALM to be NO and parallel wired.
If drives are NO then pages 17-19 of your manual applies.

If drives are NC (or even limits are NC) I would use a breakout board with this controller so polarities can be swapped to suit each component with ease.

[fastbike]

Thanks for the feedback. I think I've got this correct and have attached a sketch to show how I will be connecting the drives to the controller.

The drives are on the left. Their manual shows an opt isolator output for the alarm and states that in normal operation the impedance across the ALM+ and ALM- is low so that sounds like the opto output transistor is saturated and therefore conducting.

I've wired these in series.

On the right is a schematic from the controller manual, the input has a jumper so it can be internally connected via a 2K7 resistor to either 24v or GND, I have chosen 24V as this works with the output of the drives. Interestingly there is no setting in the software so I'm assuming that teh controller sensing a change in level from 0v to 24v to indicate an active fault.

The driver manual shows the ALM+ connected to 5-24V via a resistor, I'm assuming the internal pullup in the controller input circuitry is sufficient and no external pullup is required.


Attachment 475168

I will be using a break out board to help make the wiring easier, although in this case the drive ALM outputs are daisy chained in series and there is only one connection to the controller so it's a moot point.

My sketch shows the internal circuitry being held at 0v by the circuit via the optos to GND during normal operation - the 24v is dropped across the internal resistor, so that around 8mA flowing to GND.
When a fault occurs, one of the opto transistors will turn off so that circuit becomes open, and the pullup resistor will then hold the internal circuitry at 24v. My guess is that the software will then react to the change rather than the absolute level.

[dazp1976]

I will be using a break out board to help make the wiring easier, although in this case the drive ALM outputs are daisy chained in series and there is only one connection to the controller so it's a moot point.

Driver image looks fine.
You say it's moot but.....
This is what I'm getting at with regards to a bob:

Example of my board below shows I+ I- as input port optocoupler.
There are 4 ways in which I can wire a trio of open/close type switches (optos). 2 ways for NC and 2 ways for NO depending on the drivers etc used.

Now the key is that no matter how this is wired up.... The single input on the connected controller itself... Sees only either on (active) or off (inactive).
That's the beauty of using a bob!.

NC series: sink/source:
https://www.cnczone.com/forums/attac...d=475190&stc=1
NO parallel: sink/source:
https://www.cnczone.com/forums/attac...d=475192&stc=1

[fastbike]

Useful info thanks - I had not considered the possibility of source vs sink. The alternative circuit (with the controller sinking the current by changing the jumper) would then become

Attachment 475202

This would then provide approx 24V to the controller input (less the voltage drop across the 3 opto output stages) for normal behaviour, and then when one of the optos opens during a fault, 0 v would be seen at the controller due to the 2k7 pull down resistor.

For safety sake I'd probably also use an external resistor between the 24v and the first drive ALM+, bearing in mind that this will create a voltage divider in conjunction with the internal pull down resistor in the controller.