When using the demo software, I can toggle the check-boxes for the outputs, and the corresponding LED on the board lights up.
Is there a simple way I can tell that the output is actually working as designed, perhaps by lighting an external led or something? Maybe even by using a multimeter…
Using a battery, resistor and a LED you can test the outputs.
Also using a multimeter in a diode test position you may test the outputs.
The meter show open circuit when the output is not activated and some value (e.g. 0.65) when the output is activated.
You should connect the plus (red) lead of the multimeter to the digital output output and minus lead to the GND terminal of the K8055.