I am building a machine which includes stepper motor , is there any way mechanical or electrical to prevent the motor to go at high speed ? Since the machine is going to be designed to work at very low speed and if for accidentally or any fault the stepper goes high speed will be very hazard. So i would like to know if there is any Safety module ecc ... that can be used if the stepper goes high speed.
I find it hard to imagine how a stepper motor could go faster than your code requires it to.
What speed will your motor normally work at and what would be the maximum safe speed?
If there is a human operator present then all motor systems should have a big red switch that simply cuts off power to the motor.
If you really need to detect the speed independently then I think you would need a second separate Arduino monitoring the pulses from a rotary encoder attached to the motor shaft.
Stepper Motor Basics (http://forum.arduino.cc/index.php?topic=284828.0)
Simple Stepper Code (http://forum.arduino.cc/index.php?topic=277692.0)
The motor will make from 1 to 3 revolutions per minute. I m going to have emergency buttons but the stepper accelerations is too fast for an operator if notice that something is wrong. I would like that the machine has a safety feature automatically.
What i was thinking is to include an inductive sensor that detects the stepper motor shaft and if for example detects 5 revs in less than a minute it will turn off a main contactor which is feeding the power supply of the stepper motor. Is it a good idea or not ?
Referring to Reply #2 ...
There is not enough info for me to give a useful answer.
In particular you did not respond to my comment in Reply #1 about the improbability of a stepper motor over-speeding. I can't help feeling either that you don't understand stepper motors or there is a significant part of the project you have not told us about.
And now that I think about it, you have not told what the project is. A general overview of the project helps us to see your questions in their proper context.