Hi guys,

I have been stuck with one task. I want to create a timer that compares from last time, but I don´t really know how to do this. Here is full text of the task:

The motor can be turned on/off by means of a button.

1. With every motor revolution, the number of revolutions is counted by means of a sensor.
2. There is a total counter and a counter for the last activation period.
3. When the motor is running, the revolutions per minute are calculated with the maximally possible accuracy and then output. After every revolution (positive edge of the sensor), the rate of rotation is calculated anew and then output.

And here is(for now) my code:

hdhosseini

Hello,

This problem is a typical University Lab . here in the forum as far as I remember , we provide assistance to optimize final solutions or rectify minor programming| hardware issues. 

as a starting point , I suggest  split the project to smaller tasks , define it in plain English (Sketch simplified diagrams , test each sub-task and compile the whole.

I hope it helps,

hdhosseini

 Hi, I did it and it works, Thank You a lot!

Hi OliviaAndersson,

that's a challenging job you have to do. I'll do my best to give you useful hints.

S5TIME:

I would not recommend using S5TIME. Here are my reasons:

• The smallest possible time basis for S5TIME is 10 ms.
• The timers (based on S5TIME) are located in the system memory, this means that they can only be used once. Reusable blocks are therefore only possible if the memory area is passed as a parameter. Furthermore, the number is limited (PLC dependent).

Better use IEC timers instead. Or in your case, maybe the "TIME_TCK" instruction would be helpful. In this case, take care of an overflow!

Common:

For speed measuring, usual specific hardware which does this measuring internal. You should be aware that the accuracy of the measurement depends on:

• Input delay of your digital input used for detecting the revolution.
• Cycle time of your PLC.

Kind regards
Stefan

Stefan Arcularius

Hi OliviaAndersson,

that's a challenging job you have to do. I'll do my best to give you useful hints.

S5TIME:

I would not recommend using S5TIME. Here are my reasons:

• The smallest possible time basis for S5TIME is 10 ms.
• The timers (based on S5TIME) are located in the system memory, this means that they can only be used once. Reusable blocks are therefore only possible if the memory area is passed as a parameter. Furthermore, the number is limited (PLC dependent).

Better use IEC timers instead. Or in your case, maybe the "TIME_TCK" instruction would be helpful. In this case, take care of an overflow!

Common:

For speed measuring, usual specific hardware which does this measuring internal. You should be aware that the accuracy of the measurement depends on:

• Input delay of your digital input used for detecting the revolution.
• Cycle time of your PLC.

Kind regards
Stefan

 I tried and it works, Thank You!