Getting "Counter" Simulink block to switch direction?

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Hey all,
I am trying to get position feedback using a quadrature encoder in Simulink. I'm using the "counter" block in Simulink to count pulses and correlate that to distance. The problem I'm having is I need to counter block to switch from increment to decrement when the encoder is turning in the opposite direction. It looks like the only way to do this is to change the count direction from UP to DOWN in the block. Is there a way to do this with a signal in Simulink? I know it can be done in Labview.
Basically, I need a block like FIGURE 3 in the following link:
  1 Comment
Curtis on 26 Apr 2014
That National instruments block is exactly what I need as well. I tried putting it together with detect change, but the counting keeps running away. Maybe you can only do in C++ s-functions or state flow.

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Answers (7)

Guy Rouleau
Guy Rouleau on 8 Mar 2011
I do not recommend using the Counter block for that. The counter block could be used to simulate the behavior of your sensor.
Using a few basic blocks like Memory and Sum, maybe a Detect change and a Triggered subsystem, you should be able to get what you are looking for.

Fangjun Jiang
Fangjun Jiang on 27 Jun 2011
Based on Walter's suggestion, you could use a Switch block (or Manual Switch block) to pass either 1 or -1 and integrate it. It will go up or down based on your switch.

jack on 8 Mar 2011
have you solved the problem yet? im facing the same problem here as well

Adam on 9 Mar 2011
I ended up doing something different. I don't think there is a way to switch the block automatically. You can make a work around using edge detect and two counters, then subtracting them to get a total count. Let me know if you have questions, I can send you an image of my block diagram. It counts up in one direction and down in another, depending on which input phase is leading.
  1 Comment
Noor Zeid
Noor Zeid on 27 Apr 2016
Hi I am having the same problem, can you help me with this? I need to take a look at the block diagram my email is:

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elahe bakhtiari
elahe bakhtiari on 26 Jun 2011
Hi.Do you solve this problem?"The problem I'm having is I need to counter block to switch from increment to decrement when the encoder is turning in the opposite direction."I need to have such block.please help me. can you help me?

James on 23 May 2012
Hope to get and answer for this too. I manage read the angular velocity from pulse reading but am stuck on how to detect direction change.

shayan on 18 Jul 2012
Hello Adam;
Can you please send me the image of your block as I am also going through same sort of problem.


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