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High Speed Input

Created by: S R R at: 4/15/2009 7:46 AM (3 Replies)

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4/15/2009 7:46 AM	Rate (0)
S R R Posts: 8 Rating: (2)	Hi As you know LOGO! (0BA6) has 4 high speed inputs with 5kHz. And I think a cycle time of LOGO! is about 25 Hz. So the question is How can LOGO! detect a digital input in High speed input? I have used the attach file to detect LOGO! sysle time in simulation Mode. Attachment Cycle Time.zip (743 Downloads)
S R R Posts: 8 Rating: (2)
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4/15/2009 9:04 AM	Rate (0)
Axel Haar Posts: 13 Rating: (5)	The 0BA6 offer 4 HSC inputs. The termination of which input supports this is fix. It is I3, I4, I5 and I6. So there is no adjustment from software required. The inputs works always in its fast mode, reagrdless if used a HSC or common digital input. The inputs cause internal (most probably) a hardware interrupt to the underlying processor, so they independent of the cycle time (of user program). Otherwise, on regular processing the LOGO would be capable to complete the cycle better than in 200uS. (1 / 5000)
Axel Haar Posts: 13 Rating: (5)
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4/15/2009 9:27 AM	Rate (0)
S R R Posts: 8 Rating: (2)	Thanks Axel It means 1. HS input independent from cycle time. 2. If I connect input I3 (for example) to a counter , the counter work properly? Could you send me a simple program? Thank you in advance for your cooperation.
S R R Posts: 8 Rating: (2)
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4/15/2009 10:24 AM	Rate (0)
Fux Posts: 661 Rating: (123)	To complete this: To count the high frequenecy you have to connect one of the 4 high speed inputs I3-I6 directly to a up/down counter or a threshold trigger. This you should be able to do by yourself. My experience is: Only if the I´s are directly connected to one of these 2 FB´s LOGO! can catch the pulses. (I think this is described also somewhere in the manual). If you connect other function blocks (like AND, OR,...) between the input and the counter/threshold trigger, its max. counting frequnecy will decrease.Please don´t ask me to which frequnecy (i think less than 1kHz). But it´s slower than 5kHz! For counting the pulses and only displaying the speed/distance in a message text it´s ok (e.g. ultrasonic sensors). For evaluating encoders / regulating something, maybeLOGO! is too slow.
Fux Posts: 661 Rating: (123)
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