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| 2/8/2016 8:45 PM | |
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Posts: 158 Rating:
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I made a pulse generator with a square wave output around 309Hz. The output voltage is 0 to about 4V. I wired into I6 (LOGO 0BA6) and in the program (.lld) wired directly to input of threshold triggger. I had another timer reset the threshold trigger once a second, and displayed these values on the screen. It worked great for 360 cycles, then the input stop 'seeing' the pulsed input. I stopped it and moved it to I5, and it worked the same, but the same thing happened after 3860 cycles. I repeated for I4, 365 cycles. I moved it to I3 and added a 10k pullup resistor, and it lasted until cycle 4227. My 2 questions are, how was the input even turning on at under 4 volts? and why did these inputs work fine, then stop working? |
| 2/8/2016 9:02 PM | |
Joined: 12/27/2006 Last visit: 3/1/2025 Posts: 1197 Rating:
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Not all the LOGO! types have High-speed inputs. What LOGO! do you have? |
| 2/8/2016 9:14 PM | |
Joined: 12/18/2014 Last visit: 3/14/2025 Posts: 34878 Rating:
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In my opinion it is the voltage level. According to the manual, the voltage level <5V as 0 signal is defined. The voltage level> 8.5 V is recognized as a 1-signal. The problem will be not working your pulse generator with the necessary voltage level in order to ensure a clear Count. AttachmentLOGO! Soft manual 0BA6 03_2009 side 253.pdf (258 Downloads) |
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| 2/8/2016 9:58 PM | |
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Posts: 158 Rating:
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You are correct...interesting how it would work beautifully, then just stop, and never restart though. I thought maybe the battery was losing charge, but each time I moved to a new input, it started working again. I'll have to try with a higher pulsing voltage. I let it run over the weekend and my 9v battery dropped to 6v.... Along these lines, I'm evaluating a sensor with an output that is superimposed on the 24VDC sensor power lines. Is this a new topology, or am I just now seeing it? It is one of a couple different outputs of an IR beam receiver. Not fining much about it online.... |
| 2/9/2016 6:43 AM | |
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Joined: 12/18/2014 Last visit: 3/14/2025 Posts: 34878 Rating:
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The fast counter input requires already a decent signal in a corresponding voltage level to be able to function properly. Can you show us your program? |
Last edited by: ixo65 at: 2/9/2016 6:44:24 AM |
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| 2/9/2016 8:02 AM | |
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Posts: 2930 Rating:
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Hi, With LOGO! to count pulses you have to make sure that the voltage is at the specified rang for = and also for 1. If not nobody can tell you what happen (counting or not). According your question. May it happen that any time you change the wiring (to different Inputs) the voltage will increase and tehn after certain cycles it goes down to a range LOGO! can detect? I belive also if you change the LOGO! you may get dirrerent time of function. This I believe can be reklated to the tollernaces of components. However: If you power you application with a stable power supply instead of a battery does it work? Regards |
| 2/9/2016 3:13 PM | |
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Posts: 158 Rating:
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If I have time, I'll try again, I'lll need to switch an opto or something, as my pulse generator is only the output of a 555 timer (TTL) so the square waves were only near 4V. I'm not sure how the logo even saw the input with that low of voltage, so I'll try switching 24V...thanks for replies..I decided to abandon the pulse monitoring and go with the resistive monitoring using an analog threshold trigger. |
| 2/9/2016 4:33 PM | |
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Posts: 158 Rating:
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got it running on a 12V battery now, working ok, input 6V pulses instead of 4V..... |
| 2/9/2016 7:42 PM | |
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Posts: 158 Rating:
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well over 12,000 cycles now...pretty sure it was low voltage. |
| 2/9/2016 8:18 PM | |
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Joined: 12/18/2014 Last visit: 3/14/2025 Posts: 34878 Rating:
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You're in luck. Actually, the voltage level is still too low with 6 VDC. |
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