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LDmicro Forum - stepper motor question

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stepper motor question (by Alex)
hello, is it possible to use a stteper motor with driver using ldmicro?
Wed Mar 27 2019, 22:37:03
(no subject) (by Ziggy)
Yes.

A qualified yes.

Depends on the driver chip.
If it calls for step and direction signal certainly Yes step rate limited to PLC cycle time.

If the driver is only there to handle motor current then the again Yes... but LDmicro ha to generate correct step sequence for forward direction and another for reverse direction.
Again step rate limited to PLC cycle time.
Thu Mar 28 2019, 00:41:01
(no subject) (by MGP)
Yes, ldmicro is certainly capable of doing something like this, in the link you see an example.
The numbers are looking stable in real life, it's because of the old camera.
In the video you can see the link to the Dutch forum where you can find the schematic and LD program.

https://www.youtube.com/watch?v=dvKA8y8042E&feature=youtu.be
Thu Mar 28 2019, 04:24:31
(no subject) (by Alex)
thanks for your reply, i have found the ladder and read the forum using google tranlastor (hope Johanna success), i have a question about the ladder, i mean, i have seen that in your ladder you have set in Plc Cycle 0.2ms, in other ladders for scada for example have seen the same cycle time , i remember a ladder for multiplexed 7 SEG-display with 0.2 ms, my point is, using that plc cycle time, woulnd┤t it be too short if i want to use big rungs, for displaying text using uart for an lcd for example, or if i make a clock inside your ladder, timers wounldn┤t be as much accurate as using 10 ms plc cycle time? i meanm, can ldmicro miss some rungs when using short plc cycle time? if i make the same in arduino IDE ?
Thu Mar 28 2019, 09:18:32
(no subject) (by Ziggy)
0.2mS at what crystal frequency?

How many instructions can the micro execute therefore per cycle?
How will You structure Your ladder so that while motor is moving only a minimal set of instructions is executed?

0.2mS implies a step rate of 5000 pulses per second.

A typical stepper motor does say 200 steps per revolution
200 steps per revolution is 25 revolutions per second or 1500revolutions per minute.

What RPM do you need?
Can You relax the cycle time specification ?
Thu Mar 28 2019, 09:27:54
(no subject) (by MGP)
I needed 1000 steps/sec, do the math ;-)

The numbers on de display are steps/sec and the distance between 2 white points is 220 steps.
Thu Mar 28 2019, 10:08:31
(no subject) (by Zoran)
In real life it depends how long is program, if You put 0,2ms and for scanning program takes 1ms it will work on 1ms.
You can see this on ATMega128 where chip is 70% full You have max 400 pulses per second.
I am trying to speed up using pulses multiplier by 4 or 8 but it doesn't work. I need schematics for it.
Thu Mar 28 2019, 12:17:31
(no subject) (by Ziggy)
The way to speed up the pulse rate is to optimise the ladder.

Clearly define what functions are required while the stepper motor needs to run and only implement those functions within the stepper motor runing state.

This way the ladder gets evaluated in portions where explicitly needed.
everything else is disabled say using master relay or some state transition scheme.
Sun Mar 31 2019, 18:21:13
Motor de passo (by Vicente)
Fiz esta aplicašŃo com arduino em uma maquina laminadora no aparelho alimentado de papel e esta funcionando bem veja o link no youtube https://www.youtube.com/watch?v=v9yGKV_Rllo
Thu May 30 2019, 18:44:17
(no subject) (by AndieDini)
Hi...i remember a ladder for multiplexed 7 SEG-display with 0.2 ms, my point is, using that plc cycle time, woulnd┤t it be too short if i want to use big rungs, for displaying text using uart for an lcd for example, or if i make a clock inside your ladder, timers wounldn┤t be as much accurate as using 10 ms plc cycle time?
Thu Jun 6 2019, 13:17:25
(no subject) (by Alex)
That is something i have always thought, but in my case i want to ask for 1ms cycle time
Thu Jun 6 2019, 13:52:06
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