WattUp

H Timer vs SM Flicker accuracy.

2 posts in this topic

I have a feeling that I know the answer, but wanted to check for confirmation. 

See attached for a quick example of what I am talking about. 

New machine has a SM410 .1s flicker to a INCP to count time passed and stop a conveyor. 

I think a H Timer would be more precise but without knowing the deep insides of the PLC I can not be sure. 

 

In the code i have done a test where I have 2 H timers that are .2s longer than set time,  I use the longer one to compare where it was when the flicker triggers the stop,  and it does vary 

TimerVSFlicker.JPG

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Should be right. An SM410 is 0.1 timer which will mean that the Depending on when the scan process line 3 you will have some variation.
Especially as your scanrate is very low. The timer will be most accurate.

But if it is accuracy you are after you should really put the program in an interrupt routine. (doesn't matter now if this is your complete program but it will when you're program scan becomes bigger)

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