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Got my AXBB yesterday. Thanks for the quick service.

Question. Is it OK to use a dual output power supply (5V & 24V), or should they be separate supplies?
Thanks.

Hi Gerry,

It depends on if the power supply has separated or common grounds?
If it has separate grounds, the 2 outputs' 0Volts are floating to eachother then it is OK,
otherwise if they share the same ground then you bypassing the optocouplers isolation and then the breakout board functionality is lost.

So, use separate power supplies or a dual one which has separate 0Volts.

To better describe this a good example for a common ground power supply is a 24VDC output where an 5Volt is made from that with a simple LDO or step down switching converter.
This topology ofcouse has a common ground and so it is not good.

The other topology is a transformer with 2 fully separate coils and they are rectified and smoothed with capacitors totally separated.
With this topology the grounds are separate and so it is good.

Switching power supplies can be with one or the other type of topology, they might have a common or separate ground.
You should check the powersupply datasheet or measure resistance between the 2 outputs' 0Volts terminal.
If it is about 0 Ohms then they are common ground and if it shows about infinite or very high resistance then the 2 grounds are separated.

I had a issue today when setting up a laser. It is powered from a 12v supply activated by pin14 port 1 and the pwm output is on pin 17 port 1 . I could not get the pwm to work until i joined the 5v ground to the 12v ground . This defeats the point of the isolayed outputs ? Is there a better way to wire it up ?

port#1 is non isolated output and so it is referenced to the 5V0 ground. The ground which is marked 5V0 and which is in the same section as the port#1 pin14.and 17., that ground is the ground point of the 5V power supply which powers the AXBB-E's digital part.
If you want the laser output signal to be isolated then you should use an isolated output instead and then it will be referenced to the 24V0 ground which is the power supply for the isolated side.

And you should possibly not common the 5V0 and 24V0, because that breaks the isolation barrier of the optocouplers in the AXBB-E controller.

I have pin 14 activating a relay that supplies 12v to the laser , the pin 17 provides a pwm 5v signal but it would not work unless I joined the 5v ground to the 12v ground.

It seemed that the 5v PWM signal had to have the same ground as the 12v supply for the PWM to work.

I understand this stops the isolation for the whole system .

How should this be wired ?

Does the isolated outputs put out a 5v PWM signal

the pin 17 provides a pwm 5v signal but it would not work unless I joined the 5v ground to the 12v ground.

The 12V power supply supplies only the laser? If yes then it should be not a problem. Or if it supplies also sensors then it can be a problem.
However it would be better to isolate the signal and drive the laser with one of the isolated outputs.

You mean it is a must we have to have 3 PS if we want to use laser, these are 5V, 12V and 24 V. In this case laser PS is 12 V. The PS 5 V and 12 V have common ground. I plan to use LED laser in the future.

Are the 5v and 24v grounds not common grounded anyway due to them both being on the 240v ground circuit , or are power supplies normally isolated between the dc and ac ground ?

If you use switching power supply, on the output there is earth, V-, and V+. So it is not common ground.