5/17/2024 1:30 PM | |
Joined: 3/25/2020 Last visit: 6/5/2024 Posts: 21 Rating: (0) |
I have such type of application (see attached). But I don't have an encoder. The conveyor belt is controlled by drive so I know the speed. Is it possible to generate a pulse train with the period which varies according to the speed? It doesn't have to be ultra precise. I use a S7-1200. Link to video: (1) Siemens TIA portal : Shift and Rotate instructions / operations SHR, SHL, ROR, ROL - YouTube |
Last edited by: The Helping Hand at: 05/17/2024 13:50:17Video embedded |
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5/17/2024 1:42 PM | |
Joined: 7/7/2010 Last visit: 6/14/2024 Posts: 14802 Rating: (2381)
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I suggest using a purpose-built piece of hardware that accepts an analog input, like 0-10V from drive analog output scaled for motor / belt speed. The signal conditioner then converts the 0-10V signal to a pulse train output with 50% duty cycle that varies pulse rate (frequence) as required for whatever needs to accept the pulse output. Keep in mind, anything that accepts this pulse train will be out of phase with the real conveyor motor / belt speed by the amount of time it takes to convert signals. Doing that in an s7-1200 is possible for slow pulse rates using a transistor dig out and cyclic interrupt OB doing the math every ~2-5 ms to determine if/when to toggle the dig out. That ~2-5ms will add to the pulse train output 50% duty cycle accuracy as well as the frequency tracking lag.
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