Interrupt single-speed positioning operation

[sid]

Is it possible to achieve the Interrupt single-speed positioning operation(which is available in FX2N-1PG module) using Fx1s PLC. I have tried using PLSY, High speed counter(c241) and DHSCS instructions. Y0 is high speed output and also tied to X0 for high speed counter and X1 tied to interrupt input(from sensor) which resets high speed counter c241. But in this case i get the variation of 4 to 5 pulses because of scan time, since dhscr instruction sets internal bit M0 which sets m8145(Y0 output pulse immediate stop).

[Sergei Troizky]

It is unclear what is your goal. If you need to stop after certain number of pulses, no need in HSC. Just define the number of pulses in the PLSY. If you want to interrupt the pulses on certain value of independent HSC, try to DHSCS M8145. Then reset it in scan when the output is idle (M8147=0).

[sid]

I am working on Tiles Printing Machine, Whenever tile enters my machine a photocell detects its entry and starts to move stepper motor, when photocell output goes low i.e tile leaves the photocell then stepper motor should moved by a specified no. of pulses and stopped so that printing cycle starts. Again when next tile enters under photocell, stepper motor starts moving continuously and after detecting photocell falling o/p it should moved to specified pulses and stops. I have tried to use m8145 with DHSCS instruction but m8145 is not getting set however if i use a RAM memeory bit(like M0) in place of m8145, it gets set. I have attached the ladder program.Ladder.pdf Edited July 21, 2006 by sid

[Sergei Troizky]

Yes, I tried to HSCS M8145 and it does not work. You still can reach your goal by HSCS a physical output connected to a high-speed input with interrupt that sets M8145. Of course, it must be an unused high-speed input available. After reading your program I have some more points. With 2ms scantime and 4kHz stepper frequency the worst error caused by scantime will be 8 steps. On another hand, you want to stop the motor from 4kHz with no deceleration. I suspect that repeatability of such stop will be much worse than 8 steps mentioned (the motor will slip). I would consider an algorythm with deceleration from some point after the tile trailing edge detected, to approach the stop target at something like 500Hz. An interrupt should latch the tile trailing edge coordinate for the stop target and deceleration point calculations. The stop to be performed in scan and will be with 1 step precision. Edited July 22, 2006 by Sergei Troizky

[sid]

Thanks Sergei, Deceleration is the best way to stay within repeatability. My one step of stepper corresponds to 1.8mm linear movment. So i need to be accurate with zero pulses, So i am trying to use two deceleration frequency first at 500pulses and second at 100pulses when there are only few pulses left. I think this should work.