Unless you have a high frequency current meter, otherwise you need to use the calculation method to calculate the current of led, you can using the O'scope to measure the output voltage of DG535, and connect the output to a 10Ω → (T)VR100Ω → Gnd, you can also adjust the VR100Ω from biggest values to the position which the output voltage of DG535 start to drawing down, and then using O'scope to measure the voltage of (T) point, the final is to calculate the I=V/R, so you can get Imax output for the DG535.
And then we using the Imax to calculate the current of led.
And then we using the Imax to calculate the current of led.
