Input for linear slide actuator

[KeepItSimpleStupid]

The cap calms RFI and brush noise.

 

[Reloadron]

Ron, what's the capacitor for?

Keep in mind the motor is mounted with the switches, which is away from the direction relay and power source. Currently it runs from a 2C cable, I'm trying to convince them to rewire with 3C. I think the new layout would require 6 or 7 conductors (2-motor, 1- power to sw common, 2 for limit sw NC, 1 or 2 for the limit sw NO)

Yeah, per KISS, the cap is to keep noise down. OK, motor mounted with switches, back to the drawing boards. I just assumed the switches were mounted somewhere on a rail in a fixed limit manner. I haven't a clue how to do it with 3 conductors and the motor using two of them.

Ron

 

[ADWSystems]

The motor is mounted to a base plate that drives a lead screw to move a slide. On the side of the base plate are two switches, one at either end. The controller is mounted elsewhere and currently only has the two wires for motor power and ground.

 

[Reloadron]

The motor is mounted to a base plate that drives a lead screw to move a slide. On the side of the base plate are two switches, one at either end. The controller is mounted elsewhere and currently only has the two wires for motor power and ground.

Ball screw linear actuators pretty much all work the same way and are controlled in several ways depending on design. You can have limit switches that are mechanical or a variety of proximity sensors. Some control motor speed and travel, some motors are basic DC reversible motors while some are stepper motors. God knows I have seen enough of them between real small to real large systems.

I assume the control for this is software driven. The existing limit switches are up there with the motor and slide assembly. Going from what was there to what is needed is the problem. There will always be two wires to the motor, that is a given. Fortunately the motor is a low current motor requiring light gauge wire. There is no way to get around the wires for the limit switches which apparently are an addition because previously this thing ran on timers for slide position and motor reversal. The limit switches can directly control the motor as most of the drawings to date have done or the limit switches can indirectly control motor reversal. The latter just involves using the limit switches to send a signal to a controller be it a micro-controller or computer software solution to make decisions when the motor reaches a limit. When doing the latter the best choice for limit switches is likely capacitive proximity sensors to avoid the switch bounce problems associated with mechanical switches. Now if the latter is chosen you will need no less than 4 wires to the two switches. You will need + and - power and the two return signals. That would be 4 wires. Again, in my opinion, mechanical switches suck when used like this because of reliability issues with switch bounce unless good debounce design practices are followed. There is no easy way around any of this and most of this should have been considered at the initial design time.

What someone may or may not want to spend to get this thing right is here nor there anymore as we have covered just about any way imaginable to do it. I certainly can't think of anymore ways to go about it. Maybe someone else will come along with a solution?

Ron