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Author Topic: Power Supply for Motion Controlling  (Read 8810 times)

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Power Supply for Motion Controlling
« on: August 16, 2010, 10:27:20 AM »
Hi there,

I am hoping somebody can help me with something that I am having trouble understanding. I am building a mechanical positioning device used to position aerodynamic probes within wind tunnel walls and it is a ball screw driven system. I have the hardware for the rig assembled and wish to apply power to the screws driving the system and control them using Mach3.

The device consists of two ball screws which I wish to control (X and Z direction travel) and the probes rotate about the Z axis then using an additional motor to rotate the probes.

I have been supplied with three stepper motors (Astrosyn MY706, Astrosyn MY703-3 and Astrosyn MY7001) and three microstepping drivers (3 x Astrosyn P402) which require 24v dc power. Ideally I would like to generate and operate a pulse train of around 500Hz (can be manufactured in house using a 555 timer is astable arrangement if needed) to apply the pulses to the drivers but I do not know if this is necessary.

What I cannot understand from reading other posts and looking at other peoples devices is how power is supplied to the motors/drivers and also how the pulse is communicated to the drivers from the 25 pin port if it does come from this port?

Does the PC supply an output voltage which can be used or is an external supply needed (24v dc)?
Also the pulses that are applied to the motor, how are they regulated if it does not come from the PC? Are the drivers regulated by relays which activate the 24v dc supply in the sequence required?

If anybody could give me some help on this or has worked on something similar and can make suggestions on the control system it would be very much appreciated as I am the first to use this software at our University so my Professor would be delighted if I could control the device using a new motion control system than the standard in our Department!!!

Please find attached a diagram of the device showing the direction(s) of travel and what it is that I am trying to power. The CAD model shows a third motor in the Y-direction, please ignore as this has been discarded due to budgetary constraints. Any other info required please ask.

Cheers,
P

Offline Hood

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Re: Power Supply for Motion Controlling
« Reply #1 on: August 16, 2010, 10:41:01 AM »
Your power supply will feed the stepper drives and you will need to make or buy a suitable one. If you look in the info section on this site http://campbelldesigns.net/ you will see a PDF that will explain how to build a power supply.

Mach can pulse at 100KHz via the parallel port although 60KHz is likely a more realistic max for most computers. However as you are requiring a max of 500Hz then you will have no issues at all.
Hood
Re: Power Supply for Motion Controlling
« Reply #2 on: August 16, 2010, 10:58:32 AM »
Hi Hood,

Thanks for your reply but what voltage will the mach3 pulse supply or does it regulate the 24v that I will supply to the drivers as they are programmed?

P

Offline Hood

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Re: Power Supply for Motion Controlling
« Reply #3 on: August 16, 2010, 11:09:34 AM »
The pulse is produced by the parallel port and it is 5v (or should be) It is totally separate from your drives power supply.
Download the Mach3Mill Install and Config Guide and look at page 4-17  it will give you an  idea of how a basic system is set up.
Hood
Re: Power Supply for Motion Controlling
« Reply #4 on: August 17, 2010, 01:57:38 PM »
Hi again, had a good go through of my equipment and the Astrosyn P402 drivers have opto isolated input signals so if I am correct (which I am not sure of!!) the 5V input into pulse, direction etc. from the printer port to each driver will activate the relays built into the driver boards and allow the motors to run from the 24v dc supply shown in the schematic below. Just wondering if anybody has ever used similar equipment and was this the layout of the equipment if so?

Also will need to integrate 4 limit/home switches and an E-stop into the system. Is it a case of just wiring them to one of the input pins, e.g. pin 10, and using mach3 to determine if the systems runs or not in the lo/high position? Perhaps somebody would be kind enough to add to the schematic if they know how they will be integrated into the electrics (afraid not very experienced at all in this department!). What I want to do is position 2 limits on each axis, X++, X-- and Y++ and Y-- and use one of each as the home origin then, along with an emergency stop in the case of misuse. I am working at a learning institute after all!!!

Cheers,

P

Offline Hood

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Re: Power Supply for Motion Controlling
« Reply #5 on: August 17, 2010, 05:18:16 PM »
Wiring looks good, personally I would use a breakout board but its not mandatory, might just be safer and also if the parallel port is low voltage most breakouts will boost the voltage to 5v.
 Not sure how the enables work but might be worthwhile feeding them through one pole of a two pole E-Stop switch, just a bit of added safety. The other pole would just connect as you have mentioned.
Limits can be all wired in series if they are normally closed switches and that way you will only use one input for all homing and limit switches.
Hood.

Offline Tweakie.CNC

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Re: Power Supply for Motion Controlling
« Reply #6 on: August 18, 2010, 03:13:05 AM »
Just a thought,

I use axis enable / disable quite a lot but I have never had the need to actually switch it during program execution.
I took my axis enable connections to three toggle switches (mounted on the side of my control box) for manual use only - and as Hood has said the common feed to the switches could run through your estop for added 'belt and braces'.
The advantage here is that it frees up 3 of the outputs from your parallel port to be used for other stuff. It's amazing how much stuff you can add in a couple of years of use.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline stirling

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Re: Power Supply for Motion Controlling
« Reply #7 on: August 18, 2010, 04:28:24 AM »
A point about your wiring diagram above. The 24Vdc supply should be *star* wired to the drives NOT *daisy-chained*.

Ian

Offline Tweakie.CNC

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Re: Power Supply for Motion Controlling
« Reply #8 on: August 18, 2010, 04:46:45 AM »
Quite right Ian - the voice of experience here.  ;)

But is this really a wiring diagram or just a schematic I wonder ?

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Power Supply for Motion Controlling
« Reply #9 on: August 18, 2010, 07:00:08 AM »
about ENABLE pin:
in industrial driver ,there are two signal (Pulse and Dir) but if we want use IC drive(sample :L297) for build driver, we have three signal(Pulse, Dir and Enable) .
In the industrial driver ,part of the embedded    Task: If the pulse is applied,then Enable pin is enabled.
If the enable pin is active for all times, power IC and motor Will be very hot.

Amir
**Even a clock that does not work is right twice a day**