#31
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I asked Steve Stallings of PMDX about mixing drives on the PMDX-122. Here is his reply:
Because the PMDX-122 does not have opto-isolation (to the drives) and thus separate grounds, you can use any GND terminal or any +5 AUX terminal to feed the common of a Gecko drive connected to the PMDX-122. The COM terminals on J1 - J4 and the jumper JP1 are just a convenience, there is nothing magic about the COM terminal on these connectors. |
#32
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Gerald, Hugo,
There should not be any damage to the circuit. What happens when the circuit is working properly is that there are a few milliamps of current going through an LED. In order to work, the Anode end of the LED is connected to a higher voltage and the Cathode end of the LED is connected to a lower voltage. In the case of the G202, the Anode end of the LED is connected to +5 volts and the cathode end of the diode is connected to a signal line. When the signal line goes LOW (near ground), current passes through the LED and the LED lights up. In the case of the G203v, the Cathode end of the LED is connected to GROUND and the Anode is connected to the signal line. When the signal line goes HIGH, current flows through the LED and the LED lights up. In either case, the amount of current going through the LED is limited to a safe level by a resistor. The JP1 jumper on the PMDX-122 determines whether the Anode is connected to +5V or the Cathode is connected to GROUND. One of the functions of a diode (like the diodes in a bridge rectifier that we use to convert AC to DC) is to block current. So, in most cases, when an LED is connected backwards, no current can flow through the device and the LED will never light up. The exception would be if we connected an LED to higher voltage than it was designed to handle. In that case, the LED could be destroyed; however, a Break Out Board only uses 5VDC on its signal lines, so no damage will occur. Because I have both G202 and G203v stepper drivers, I have often forgotten to move the JP1 jumper when I've connected different devices to the PMDX-122 board. In every case, as soon as I moved the jumper to the correct position, everything worked properly. Last edited by Richards; Mon 22 October 2007 at 13:35.. |
#33
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Thanks Gerald for your interest in helping .
Mike, is a pleasure reading your comments. I am really learning more of my electronics (the heart of the baby beast)then if I had not go through these problem so I am glad with the situation. I heard of so many cases that is just a simple thing what is wrong that I am sure this is one of those situations. These baby beast show me how strong and precise she is so I have to learn more, how to take complete care of her. |
#34
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What is the best drive to start a machine G203V or g202 or others?
I pretend to use G-Rex G100 / drive g202 / and motor Phase Stepping Motor - PK296A1A-SG7.2 2-Phase Stepping Motor . Any sugestion, idea etc? sorry of my English. Thanks, Marcos Pilar Brazil |
#35
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Marcos,
The stepper motor determines the stepper drive that is best for you. If you already have PK296A1A-SG7.2 stepper motors, then the "best" stepper driver for that motor would be the G202. That is because that motor has high inductance and the G202 is better suited for that motor. If you have not already bought your motors, I would suggest the PK296A2A-SG7.2 motors, the G203v stepper drives and the PMDX-122 breakout board. The PMDX-122 is a very good breakout board if you're using a parallel port. There are many other good breakout boards that others prefer. I've only used the PMDX in my testing. The G100 is being discontinued. I have a G100 and also a G101/G102. They are excellent devices, but Art and Steve (at Artisoft) have had serious difficulties making the G100 work as well as they had hoped. However, they are working with other devices that should give us most of the good features of the G100 without the expense or the difficulty. The power supply that you use will depend on the motors that you select. The PK296A1A-SG7.2 wired either bipolar series or half-coil can use a 70VDC power supply. The PK296A2A-SG7.2 motor would use a 30V to 35V power supply if you wire it half-coil or a 50V to 70V power supply if you wire it bipolar series. (I prefer half-coil, but either will work.) |
#36
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A new question in regards to the GECKO 203v...
It automatically uses microstepping for low RPM's right... and as the RPM's get higher it switches to a fullstep routine... Question: How do you set the step per linear unit in mach3? We do the calculations for 200 steps per revolution (full step motor) or 2000 steps per revolution (microstepping)??? Francis |
#37
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Francis,
You use 2,000 steps per motor shaft revolution to compute the number of steps per inch or mm. The "morphing" from 2,000 steps per revolution to 200 steps per revolution is handled by the driver. You just keep feeding it 2,000 steps per revolution and the G203v takes care of the rest. |
#38
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Hi All,
Was about to order the 203V model but am unsure about the version to get. Standard, vacuum or CW/CCW? can you help me out? cheers |
#39
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Hi Jason
Where do you see these different versions of a Geckodrive G203V ? The last I looked, it only came in one flavour. |
#40
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Gerald,
Gecko has done a major face lift to their web site and now under the G203V there is those unheard option ( Vacuum, CW / CCW ?? Worth investigating, us juniors out here are wondering with out making to much noise until you big guns tell & say more on those & what they mean !!?? Amicalement, Robert |
#41
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That new page doesn't work on this side of the Atlantic yet.
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#42
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Try this http://www.geckodrive.com/product.aspx?c=3&i=14460
and if that don't work try this G203V
G203V Manual (PDF) How the G203V Gets the Most Out of Your Motor Standard$147.00Qty: Vacuum$147.00Qty: CW/CCW$147.00Qty: Last edited by J.R. Hatcher; Wed 30 July 2008 at 05:34.. |
#43
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Oh, those things were mentioned on their yahoo forum a couple of days ago.
We, together with most of their customers, would use the "Standard" version for Mach3. |
#44
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On their forum:
http://finance.groups.yahoo.com/grou.../message/15745 Quote: Our new drives are CPLD based and have about 8 or 10 macrocells unused. Recently someone wanted a CW/CCW interface instead of a STP/DIR one. Piece of cake. Marcus changed 6 lines in Verilog, used up 2 macrocells and after a half-hour of work delivered the interface. Not one hardware part had to be changed on the target G203V. STP became CW, DIR became CCW. Another time a big laboratory need standby current to go to zero because the motors operated in a vacuum chamber. Vacuum is not world famous for effective heat dissipation. Again, a couple of lines in Verilog was changed and presto, zero current during standby. Furthermore, the windings were shorted during standby to make the motor resistant to being back-driven. |
#45
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Seems only firmware changes so I've gone with the standard.
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#46
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201x changes make it a better candidate for MM?
I have 0 experience with drivers so I may ask a dumb question. Please point them out to me so I learn.
I am wondering if anyone has had a chance to look at the changes made to the 201x and if the changes make it a good/better candidate for the MM than the 201. I have read that this was built around the 203v design but from what I can tell, it is missing the Short-circuit, Reversed-polarity, Over-temperature, Over-voltage protections of the 203v. Is this the killer? 7A 80VDC power rating 10 microstep fixed resolution Optoisolated step / direction Mid-band resonance damping Silent 20kHz PWM switching No low-speed vibration STEP and DIRECTION is +3.3VDC and +5VDC compatible at 2.5mA Recirculate mode during STANDBY greatly reduces motor heating No external 470uF capacitor is required Power-on RESET DIRECTION is clocked in on the active step pulse edge No internal jumpers No current set resistor required All settings done using a 10 position DIP switch Universal step and direction COMMON |
#47
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The 201X is the new replacement design for the 201. At this point you would not be able to buy a 201 new. You are correct that the 201X does not have all the safety features of the 203V. If your motors fall within the drive capabilities of the 203V then that drive, in my opinion would be a better choice. The 201X might drive a higher inductance motor though.
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#48
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201X with PMDX-132?
Anyone tried the 201X drives with the PMDX 132? I like the layout of the 132 until i noticed that there was no way to tune the motors when using the 203V. But the 201X has the adjustment on the back of the drive, instead of the top.
Just wondering... -Cody |
#49
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Cody,
Look again at the PMDX 132 BOB board. The tuning screw is opposite of the pin header. Depending if you mount the BOB vertical or horizontal, tuning that drive might not be a big issue. If you mounted it close to the edge of the case, you might be able to register a pin hole with dust grommet for each drive so you could tune with the enclosure door shut and "hands away from power". Just thinking! Are you planning for next year already or a summer project? Sean |
#50
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Just wishing.
No real plans yet. Just thinking. I was/am thinking about building a small footprint machine using the mm box, and then building the big machine later, as I don't have anywhere to put it right now.
Also thinking of maybe doing my thesis on multiple-axis machines and control, and maybe incorporating servos or steppers into that. Mainly just spinning gears... -Cody |
#51
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Gecko 213v
Are the new 213V drives what we should be ordering? Better for direct drive machines? Gecko's info is not clear why you should use these
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#52
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you should use the 203v, the 213v adds no new benefits for a mechmate machine, unless you want to use it with half step or anything different from 10 microsteps, and its also more expensive!
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#53
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Gecko 213v
Thanks Pablo,
Still don't know what the benefits of micro stepping are though? more research required! |
#54
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Microstepping helps keep the motor motion smooth at lower speeds, and thus produces more useful torque. Think about riding a bicycle using one leg instead of two, or running an engine on fewer cylinders than designed - there is a cogging effect.
Microstepping smooths this, but it requires more pulses (like 8x or 10x or 16x), and thus you need a faster pulse train for the same motor speed. Because the pulse train can be limited by factors in the computer hardware, you can add a step multiplier back in, giving you the smoothness advantages of microstepping without limiting your top speed. That's one of the things added with a G213. However, it isn't generally needed on a MechMate. |
#55
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Some Geckodrive stepper drivers, like the G213v have a pulse multiplier built in. The pulse multiplier gives 1, 2, 5 or 10 output pulses for every input pulse. Those drives with pulse multipliers are normally used when your pulse source can only produce a slow pulse train or when you need extremely fast movement (which means hight temperatures and low torque).
Most people will find that moving the motor at 1,000 RPM maximum is plenty fast for a CNC router. With a 1.25-inch spur gear and a 7.2:1 gear box, that will be about 550 inches per minute. That will also require about 33,333 pulses per second. Depending on the power supply and the motors, that speed is not difficult to achieve. With a standard G203v, you will get about 0.00027-inch per step resolution. With a step multiplier board, you would get 2x, 5x, or 10X worse resolution. |
#56
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Does the coming G215 have adventages over the G203v for MM builders ??
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#57
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Here is the link G215. http://www.geckodrive.com/images/fck...on%20Sheet.pdf
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#58
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Guillermo,
The G215 is targeted towards "simple automation" (running a repetitive task without the need of Mach 3 or other software). From the little information that is available, and from the video on YouTube, it looks like that drive would be better suited for non-CNC applications. The G215 contains special circuitry to allow it to create its own pulse stream, to sense "limits", to automatically reverse its direction. In short, it would be an ideal stepper driver for process control applications where a fixed-cycle repetitive movement needs to be controlled. The G203v and the G201x, along with Mach 3 as the pulse generator, would be more than adequate for varied movement CNC applications. |
#59
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Thanks Mike
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#60
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I'll second the "Thanks, Mike."
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