Hello John0196,

Why so complicated? If both pulleys are the same size and you don't display the speed, you only need the difference between the two pulleys. It doesn't matter in which unit this is done .

With two threshold switches you record the frequency of the pulleys and compare it with a comparator. The threshold values ​​of these comparators are then used for the error or alarm messages. This saves unnecessary conversions.

Greetings Ella_68

Hi Ella_68,

I'm displaying the speed information and there are more details about the programming outside of the scope of this topic. That is why I didn't want to share everything so I don't complicate things more lol. 

As I mentioned before, the sensor sends pulses, not frequency. I just use the frequency version input for testing purposes. 2 pulses for one revolution.(If you meant those conversions)

I think my concern is, if we imagine this program as an elevator safety; when the following pulley is slipping and not enough spinning, in the Level 1 Alarm, it warns the "security" and in the Level 2 Alarm, it stops the elevator as an emergency. For my concern, what if there is an emergency and since I put the time delay("For Level 2 alarming, I have a time delay(T058) if the Level 2 alarm continues for the 2nd 6-second frame."), those 7 seconds might be crucial in this example. Or how would you design something like this safety procedure? 

Thanks!

Hello John0196,

The sensor emits a number of pulses in a certain time, depending on the speed. Frequency = pulses per time (f=1/t, so 1Hz=1^/1s).

Elevator safety , don't know what the regulations are in your country, but I have strict regulations and laws regarding the construction and operation of such systems. This is checked at regular intervals by approved testing companies (TÜV).

I would stay away from it without all the regulations and approved safety devices. Almost all PLCs do not meet the requirements for a safety device in any way. Especially not a logo...

To stop a slipping elevator, there is the safety catch (invented in 1853 by Elisha Graves Otis).

Regards Ella_68

Hi Ella_68,

Sorry for the late response.

I wanted to use the elevator as an example since the logic is similar to what I'm trying to do. It's not an actual elevator, so we don't have to worry about the regulations for this.

Thanks

Well, ultimately you are measuring impulses per time (frequency) and to what extent a deliberate delay damages the system and leads to a hazard is something only you, who alone has the overall overview, can assess.

If you have any questions about the circuit, please contact me.

Regards Ella_68