Sometimes you want to control a VFD with multiple digital outputs, instead of using a 0-10v or 4-20ma analog speed signal.
Danfoss has a couple of ways to do this:
1. For one preset speed, you can use the "jog" function in the VFD.
Set parameter 5-11 Term 19 (or any open input) to  Jog. When you turn this input on, the drive will automatically go to the speed that you have set in parameter 3-11 Jog Speed--this will happen regardless if you have a regular s/s turned on.
2. For multiple speeds (like a low/high exhaust fan at a potato chip factory- Hi John!) you can use the "preset reference array" giving you up to 8 speeds with just 3 digital inputs.
Set parameter 3-04 to  "sum"- basically adding all of the input, external and preset references.
Set parameter 3-10 "preset reference" values-- remember this is an "array" with up to 8 different values. In the example below we set "preset ref 0" to 30Hz (50%), and "preset ref 1" to 45Hz (75%)-- these are the two speeds that we want the drive to run in this example.
Set 5-11 Term 19 (or any open input) to  "ref bit 0"
When the S/S is received, the drive will ramp up past the min speed to 30Hz, if you turn Input 19 on then the drive will speed up to 45Hz. You can see that if you added 2 additional inputs you could get access to all 8 different speeds per the matrix below--- just by turning on and off the 3 input points. As usual call us if you need any help here.
If you just want to activate the speeds with the reference bits only (no separate start/stop input, the drive only runs when you have a speed reference on it, otherwise it stops)
Setup the preset reference array like above.
Test your speed commands by jumpering the reference array inputs, you should see the reference values change.
JUMPER the start/stop so it is always on
Set parameter 1-82 “min speed for function at stop” to be just slightly higher than the minimum motor speed. For example, if the min motor speed is 12 Hz, make 1-82 13Hz. That way, when there are no other references commanded on the drive will go to sleep when it drops below 15Hz.