Enable pins

[ScotY]

Can someone tell me what the EN enable pins do and when? I’m trying to wire in an enable/disable feature for the Dyn4 drive.

I’m using EN4 and need it to go to Acorn common when the e-stop is activated. I have the 4th axis inverted in the Wizard but it’s not working. There is continuity between EN4 and COM regardless of the e-stop condition.

If I un-invert the 4th axis, I measure about 2vdc between EN4 and COM. I don’t understand how this works.

Per the DMM manual, I have pin 16 on the JP4 DB-25 connector connected to +24vdc. Pin 15 is supposed to be connected to EN on the Acorn. When pin 15 sees COM, the motor will be disabled. I have tested this and it does disable the drive. I just can’t seem to get the EN pin to go from COM state to a non-COM state.

Hope that makes sense. Electronically challenged.

Thanks, Scot

[cncman172]

Most drivers for steppers and servos have an enable input. If your control does not have that output you normally need to enable the drive by grounding that enable input. If the enable is not activated the stepper motor will have no holding current, and the same in servo systems. When to tell Acorn to move with jogging or gcode motion it drives the enable signal.

Russ

[ScotY]

Where is everyone this weekend? Looking for eggs?

[ScotY]

Anyone?

[SteWoe]

I followed the DMM wiring sheet for Acorn and connected the Acorn ENA pin to DYN2 ENA pin via a 2k resistor. In the Acorn wizard I activated the inversion of the Enabling signal for all axes. Don’t know if it’s the same for DYN4, however...

[Centroid_Tech]

The ENA signal is an Enable signal which some drives require to tell it that it should be expecting signals to spin the motor. By default, the ACORN will pull the ENA output to COM when it's energized. If you are using the screw terminals, the ENA is an open collector output which means that the output is pulled to COM when active and floating when not active. That is why there needs to be some type of pullup resistor to pull that signal to whatever voltage is needed for the drive. The output on the DB25 connector is tied to a push-pull driver which means that the output will either be 0V or +5V.

Some drives require the inputs to be an active HIGH signal rather than an active LOW signal. In order to accommodate for those drives, you can invert the output using the wizard so that in an active state, the output will float rather than being pulled down to COM and will be pulled to COM when in an inactive state. Some drives may have a jumper or a parameter which can be set to tell the drive whether the inputs are expecting to be active HIGH or LOW.

[ScotY]

That is why there needs to be some type of pullup resistor to pull that signal to whatever voltage is needed for the drive. The output on the DB25 connector is tied to a push-pull driver which means that the output will either be 0V or +5V.

Thank you for the detailed explanation! The above paragraph is a little unclear to me. When you say a pull up resistor is needed, I don’t understand what that means.

I think this means the enable wire connected to the Acorn EN pin has to have voltage on it, whatever the drive requires (or whatever is coming out of the pin from the drive?). If the voltage is in excess of what Acorn can handle (24v), then a resistor is needed in the line to drop the voltage?

Am I understanding how this works? I think I already get it, in theory anyway, but just want/need to learn how to interpret all the electronics jargon.

[DICKEYBIRD]

When you say a pull up resistor is needed, I don’t understand what that means.

My youngest grandson wears pull-ups; you want I should ask him for advice? .[/quote]

[Centroid_Tech]

The concept of an open collector output is that when the transistor is enabled, the collector of that transistor is pulled to the emitter of that transistor which in our circuit the emitter is connected to COM or the ground terminal of the power supply. When that transmitter is not active, the collector of that transistor is just floating. There is no voltage associated with that terminal. That is why you need to add a "pullup" component such as a resistor which will pull that floating point up to some voltage, +VDC. Some drives use +5VDC logic while others use +12VDC logic while others use +24VDC logic.

Don't think of the open collector output as "supplying voltage" as it does not do that. On the ACORN, all it does is tie the output to COM whenever it's active. When it's not active, the output is floating so there is no voltage on that terminal until you connect a "pullup" device such as a resistor which one side is connected to the output while the other side is connected to the required voltage that is needed. The "pullup" device is not a protection device for that output. On newer revisions of ACORN there is protection circuitry on board that will prevent the open collector outputs from exceeding +24VDC in order to minimize damage.