Three wire control is super easy to setup.
The default drive is configured for 2-wire operation using maintained selector switches
and is wired like this.
To change to three wire control, just swap the selector switches with momentary switches
and add a third normally closed momentary switch for stop control.
We’ll use input terminal P3 for that.
These are the built-in digital inputs that come with the drive, the parameters used to
configure them and the default values.
Using terminal P1 and P2 to control the direction is exactly what we want so no changes needed
here.
We’ll use digital input P3 - which defaults to an output inhibit - for the stop button
which is code 14.
Let’s do it.
In the product insert quick start guide, there’s a diagram showing us how to wire this.
I already wired these three switches to the drive as shown in that diagram.
If you don’t have that guide remember that you can always download it and all the other
documentation – including 3D CAD models - from AutomationDirect.com.
I love that these Ironhorse ACN drives can be ordered with a built-in disconnect.
That saves me time, money and mounting space.
Let’s fire this thing up.
We’ll reset the drive to factory default so you know exactly where we are am starting
from.
Right arrow to the drives group.
Down arrow to parameter 93.
Enter a 1.
Select it, accept it.
Uh-oh.
What’s wrong?
We have a Bx on the display and all the LEDs are flashing.
Well, we wired a normally closed switch to input P3 which by default is the Block Drive
Output signal.
This display is telling us the drives output is currently being blocked because that input
contact is closed.
If I press that normally closed witch to open it the drive stops blocking the output.
So let’s change digital input P3 to be the 3-wire stop input.
I can’t do anything while this output block message is active.
I could hold the button down to deactivate the block while I change P3, but another way
to do it is to hit the up arrow once, then right arrow to the input parameter group.
Parameter 67 … and change it to a 14 which replaces the output block with the 3-wire
stop button.
This changes the input terminals to latching inputs, so they work with a momentary contact.
Enter to select, enter to accept.
Escape to the top level and the output block is no longer active.
Perfect.
Let’s change the frequency to something that’s not zero… how about 20 Hz.
Enter to select, enter to accept.
The default acceleration and deceleration values are really long, so let’ change those
so we don’t have to wait on them during the video.
Up arrow to the acceleration parameter, enter to accept.
Change it to something shorter.
Enter to select, enter to accept.
Up arrow to the deceleration, enter to select.
I’ll change that to something a lot shorter.
Enter to select, enter to accept.
Escape back to the top-level frequency display.
Hit RUN.
Nothing – exactly what we expect because we told the drive to use these push buttons
for control.
Press the forward push button, and yep, we ramp up to 20 Hz in the forward direction.
Notice that I’m not holding the button down.
Press the reverse push button and the drive automatically ramps down, and then back up
in the reverse direction.
Perfect.
Hit the STOP push button to stop.
That’s all there is to it!
By the way, if you need more digital inputs the optional extended IO module adds three
more digital inputs amongst other things.
So check that out if you need more I/O. It just plugs in the drive here.
Click here to learn more about the Ironhorse Nema4X drives.
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