PWN? Do you mean PWM (Pulse Width Modulation)?

That's a constant current driver, so the dimming function adjusts the current (see page 4 of the manual). If you measure the driver current you should see that it varies proportionally to the dim percentage.

If you measure 24v across a 3 parallel, 7 series light, that means each diode is at 24/7 = 3.43v across each diode. That's a lot for a white LED and could indicate a fault. I'd expect 22v or less. Either way the max voltage of the driver is 24v, so that is as high as it will go.

@user1850479 yeah I think I'm not really understanding how it is able to adjust the current, while the voltage is fixed, given that the LED has a fixed resistance. It could adjust average current (e.g. averaged over a second) by tuning itself on an off, which is called PWN, which is basically a special kind of AC typically with rectangular wave shape. Page 4 just says that current varies from 0 to 100%. It doesn't actually explain how. Is it changing voltage or is it applying some PWM?

It adjusts current by slightly changing voltage. Since LEDs don't have resistance (they're diodes), the voltage changes will be small relative to the change in current but they can still be used to control current.

@Transistor no, it doesn't look like there is anything on the board except for the LEDs ibb.co/jv45dkLm it's labeled 2835 and 3B7C, where 2835 is the chip and 3B7C has something to do with the layout. I read the article, you explained how the input works, but I am not sure I understand what specifically should happen as a result of varying the input i.e. what specifically does it do to the output voltage? How do I know it works? Do I hook it up to an oscilloscopes and see the shape of the variable voltage curve change?

It looks like LEDs have dynamic resistance. I still don't understand how ELG dims. Does it change the voltage or does it pulse? Also, why am I unable to dim the LEDs I have with the power supply I have, and how do I troubleshoot from here? I thought the issue was the control signal to the power supply but after trying the resistor approach, it really doesn't look like that's the issue.

@user1850479 LEDs do have resistance, otherwise they would not emit light. It's just not constant, and it's not very large.

Diodes have an I-V curve not a resistance.

@Transistor yes, PWM, fixed. I am really not sure how to troubleshoot this further so any advice would be much appreciated

The datasheet is a little "foggy". It suggests (on top of page 4) that the 'B' model controls output current. Are you sure you haven't got an 'A' model? Just to rule stuff out, try measuring the voltage on the dimmer input as you vary the resistance across the input wires. 10k should give you 1 V. 20k should give you 2 V, etc.

@Transistor I think the issue is that since he's at the top of the compliance voltage range (12-24v) but commanding a high brightness nothing happens since he's already maxed out. What is less clear to me is how he needs more than 24v to light up 7 series white LEDs.

@user1850479 I don't need more than 24v. The LED array needs less than that. In fact when I measure the output of the original power supply with a multimeter at full brightness, I see 21v, so if anything I need to adjust the top voltage down, not up. The LEDs are rated 21-24v according to spec sheets for similar-labelled LED boards

@Transistor all power supplies I have are definitely labelled B, so I hope that's what they are. I will doublecheck the voltage at DIM. Does it matter if it's under load or not?

"The multimeter goes from 21v to 24v around 18% to about 30%" <- do I understand correctly that you measured 24v across the array?

@Transistor yes, confirmed, 10kΩ -> 1v, 20kΩ -> 2v ....

@user1850479 the driver was connected to Shelly 0-10 V Dimmer which outputs a passive PWM signal to communicate with the driver (unsure if the frequency is compatible). The LED array was connected to the output of the driver. Below the Shelly value of 18% I was getting no glow from the LED array. At this time the voltage as measured by a multimeter at the output pins of the driver was measuring 21v. As I increased the Shelly value over HTTP from 18% to about 30% (can't recall the exact number) the voltage as measured on the outputs of the driver and applied to the LED array was 24v.

If the driver needs 24V to reach the set brightness then that means that your LEDs need at least 24V and probably more. To reiterate my point above: this is not normal and sounds like something is wrong with your lights. You should investigate why they require so much more voltage than normal. Or if the array really is speced to use an unusually high voltage then you'd need to buy a higher voltage driver.

Just a thought, but you didn't connect the three groups of lights in series by any chance? Shouldn't they be wired in parallel?

@Transistor I am building a prototype with a single light at the moment. The final architecture will have 3 totally separate systems, each of them with 9 to 11 lights, all in parallel so each light will be receiving the same voltage as a single light is receiving right now.

@user1850479 sorry I am not following at all. Why do you say the drive needs 24v to reach the set brightness? Also why do you conclude that the array requires more voltage than normal? BTW, the native drivers that came with the lights have weird specs (may be inaccurate): 21-48v 280-300ma. Originally I thought this meant they dim using voltage from 21 being the lowest setting and 48 being the highest. I originally bought 48v 0-10v drivers. I connected one light and instantly fried it. Then I checked real voltage on original driver and discovered it was only 21v (not sure about PWM if any)