Limit switches to control motor direction

In summary, the relay appears to be working correctly, but the motor does not seem to be rotating in the correct direction. The stop function is also not working correctly.
  • #1
zxcvb
10
1
I am trying to use two limit switches(this one) and two DPDT relays to control the direction of the motor. When the power is applied the motor should rotate one direction (direction for this question isn't important). Also, at this point (initialization) neither switch will be energized. The motor will rotate and move until it energizes the second limit switch (labeled Switch 2). At this point, the direction of the motor should reverse. The motor and hardware will then move towards switch one. Once the motor reaches switch one it should stop completely (not reverse direction again). Below is my basic wiring diagram.

I wired it up and when I supply power the motor rotates. However, whenever switch 2 is energized I can hear relay 2 energize and de-energizes quickly but no motor rotation.

Also, I am trying to implement a latching relay when the motor reverses direction. I do not know if my problem is occurring there.

Finally, I am having problems trying to figure out how to have the motor stop once switch 1 is energized.

Any help with my two problems (reversal of direction, and stop when switch 1 energized) would be greatly appreciated.
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  • #2
What type of motor? Permanent magnet motor?
 
  • #3
First some standard shorthand:
K1 = relay 1
K2 = relay 2
S1 = limit switch 1
S2 = limit switch 2

Please verify if this is what you think is happening:

Event 1: (power on) K1 is energized, K2 is de-energized. S1 and S2 are both dis-engaged. Motor is spinning and motion is toward S2.
Event 2: (S2 engaged) K2 is energized, which de-energizes K1. Motor spins to produce motion towards S1.
Event 3: (S2 dis-engaged) K2 is de-energized, which energizes K1. Motor spins to produce motion towards S2.
Event 4: (S2 engaged) K2 is energized, which de-energizes K1. Motor spins to produce motion towards S1.
Event 5: (S2 dis-engaged) K2 is de-energized, which energizes K1. Motor spins to produce motion towards S2.
etc.

This should produce some observable chattering, unless I mis-interpreted your drawing.
 
  • #4
Do you have a data sheet for the relays? Shouldn't the relay short the NO pins and disconnect the NC pins when it's energized? You have relay 1 wired as if the pins are going to be connected to the common or supply voltages depending on its state.
 
  • #5
aam... why wouldn't you buy a Motor Driver IC with parameters of your motor? it comes with a datasheet with connection diagrams and operational manual.
these specialized IC s are chap, tiny,Bipolar,have built in voltage/current limiting/regulation and short circuit protection,are available for wide spectrum of motors, and take all the engineering weight off your shoulders. it's a "Buy-Solder-Off You Go" thing.
 

What is a limit switch?

A limit switch is a type of sensor that is used to detect the physical presence of an object or to monitor the position of a moving part. It is commonly used in industrial and manufacturing settings to control the movement of machinery or equipment.

How does a limit switch work?

A limit switch typically consists of a mechanical actuator that is connected to an electrical switch. When the actuator makes contact with an object, it triggers the switch to open or close, depending on the design of the switch. This change in the electrical signal is then used to control the direction of the motor.

Why are limit switches used to control motor direction?

Limit switches are used to control motor direction because they provide a reliable and precise way to detect the physical presence or movement of an object. This allows for accurate control of the motor's direction and can prevent damage to the motor or other components in the system.

What are the different types of limit switches?

There are several types of limit switches, including lever switches, plunger switches, roller switches, and proximity switches. Each type has its own unique design and is suited for different applications. For example, lever switches are often used in doors or gates, while proximity switches are commonly used in automated machinery.

How are limit switches installed and maintained?

Limit switches are typically installed near the moving part or object that needs to be detected. They are connected to a control system or motor through electrical wiring. To maintain their proper functioning, limit switches should be regularly inspected for wear and tear and cleaned or replaced as needed.

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