[klmjr]

Jack,

As requested, I modified a G201 manual for the G251. This includes the correct pinout and all other info pertaining to the drive. This is for the current revision, so there will be changes made before the new one comes out, including drawings of the drive and other pertinent information.

This has had a brief 5PM proof read, and my mind is not firing on all cylinders so I am sure there are quite a few mistakes in there, so if you find any please let me know. I will be making one for the G250 some time soon as well, and will be posting any stuff I think of regarding the new drives.

The G540 manual will take a little longer, because I have no idea where to begin. Haha, it is kind of the freak of the litter because it is not like anything we have produced before, so I will have to type a completely new manual for that from scratch. Enjoy!

-Marcus Freimanis

The hookups for 9 10 and 11 are off by one line. Cant wait to get mine and start playing. Have the shipped yet for the contest winners?
klmjr

[skmetal7]

"CAUTION! Never put a switch on the DC side of the power supply! This will damage, if not destroy, your drive!"

so how do you cut power to the drive? If I turn off my PS, there is still current in the caps to run the drives for several seconds. I have an estop on the dc side of the PS to cut the power to the drives.

[alipavsky]

Jack,

As requested, I modified a G201 manual for the G251. This includes the correct pinout and all other info pertaining to the drive. This is for the current revision, so there will be changes made before the new one comes out, including drawings of the drive and other pertinent information.

This has had a brief 5PM proof read, and my mind is not firing on all cylinders so I am sure there are quite a few mistakes in there, so if you find any please let me know. I will be making one for the G250 some time soon as well, and will be posting any stuff I think of regarding the new drives.

The G540 manual will take a little longer, because I have no idea where to begin. Haha, it is kind of the freak of the litter because it is not like anything we have produced before, so I will have to type a completely new manual for that from scratch. Enjoy!

-Marcus Freimanis

Hi Marcus,
I didn't think Rev.3 had idle current reduction. Didn't your dad mention that was only added to the Rev.5 drives coming out?

Thanks,
Andrey

[phomann]

"CAUTION! Never put a switch on the DC side of the power supply! This will damage, if not destroy, your drive!"

so how do you cut power to the drive? If I turn off my PS, there is still current in the caps to run the drives for several seconds. I have an estop on the dc side of the PS to cut the power to the drives.

Have you ESOP cut power to the AC side. Use a power dump circuit on the DC side so that when power is removed from the AC side a load is switched in to the DC side to suck up all residual power.

I think there are some circuits on the Gecko Yahoo Group, or look at http://www.candcnc.com They have such devices I think.

Cheers,

Peter.

[LeeWay]

"CAUTION! Never put a switch on the DC side of the power supply! This will damage, if not destroy, your drive!"

so how do you cut power to the drive? If I turn off my PS, there is still current in the caps to run the drives for several seconds. I have an estop on the dc side of the PS to cut the power to the drives.

It may not hurt drives at all if you use lower voltage PS's. Mariss gave this info on the yahoo Group.

Bleeder resistors are only necessary when a power supply has no load
attached. If drives are hardwired to the supply, they discharge the
capacitor quickly.

Let's assume you have a 72VDC power supply rated at 15A and the
capacitor is scaled for a 10% ripple voltage with 50Hz mains. That
makes the capacitor size 20,000uF.

uF = 100,000 * I / V; 20,000 uF = 100,000 * 15A / 72V

Let's also assume you have 3 axis worth of drives, each drawing 0.33A
at idle. You interrupt the AC supply and the capacitor will discharge
from 72VDC to 18VDC in one second.

seconds = C dv / I; 1.08 sec = 0.02F (72V - 18V) / 1A

You may be familiar with our drives in the DIY context but the vast
majority are sold to large OEMs for use in embedded industrial
applications. To my knowledge, none of these OEMs switch the DC side
of the supply because it is generally accepted as bad practice to do so.

I cannot imagine a situation where it is beneficial to leave a power
supply on while connecting a capacitive load. If you want a rapid stop
using step motors, interrupt the step pulses going to the drive. If
you want a rapid stop using a servomotor, interrupt the AC mains and
crowbar the DC side with a dynamic breaking resistor load.

In the above example the 20,000uF capacitor charged to 72VDC holds 52
Joules of energy. This is equivalent to a 100kg mass moving at 1 meter
per second (220 lbs moving at 40 inches per second). A 10A dynamic
load resistor would bring the load to a stop and discharge the
capacitor in 1/5 of a second.

Mariss





You could easily switch off the DC side of the PS for an ESTOP on a hobby machine I think will no ill effects.
It is switching the DC side on that is a possible killer. Mariss says this is a brutal thing to do to a nice drive. I concur.

My post started just before #14927. Check out Mariss's posts #'s 14982 and 14988.

If you always used the DC switch first and then close the AC switch, it would likely not harm anything, but if you screw up just once, it may be curtains for the drives.

[Burn]

It may not hurt drives at all if you use lower voltage PS's. Mariss gave this info on the yahoo Group.

Bleeder resistors are only necessary when a power supply has no load
attached. If drives are hardwired to the supply, they discharge the
capacitor quickly.

Let's assume you have a 72VDC power supply rated at 15A and the
capacitor is scaled for a 10% ripple voltage with 50Hz mains. That
makes the capacitor size 20,000uF.

uF = 100,000 * I / V; 20,000 uF = 100,000 * 15A / 72V

Let's also assume you have 3 axis worth of drives, each drawing 0.33A
at idle. You interrupt the AC supply and the capacitor will discharge
from 72VDC to 18VDC in one second.

seconds = C dv / I; 1.08 sec = 0.02F (72V - 18V) / 1A

You may be familiar with our drives in the DIY context but the vast
majority are sold to large OEMs for use in embedded industrial
applications. To my knowledge, none of these OEMs switch the DC side
of the supply because it is generally accepted as bad practice to do so.

I cannot imagine a situation where it is beneficial to leave a power
supply on while connecting a capacitive load. If you want a rapid stop
using step motors, interrupt the step pulses going to the drive. If
you want a rapid stop using a servomotor, interrupt the AC mains and
crowbar the DC side with a dynamic breaking resistor load.

In the above example the 20,000uF capacitor charged to 72VDC holds 52
Joules of energy. This is equivalent to a 100kg mass moving at 1 meter
per second (220 lbs moving at 40 inches per second). A 10A dynamic
load resistor would bring the load to a stop and discharge the
capacitor in 1/5 of a second.

Mariss





You could easily switch off the DC side of the PS for an ESTOP on a hobby machine I think will no ill effects.
It is switching the DC side on that is a possible killer. Mariss says this is a brutal thing to do to a nice drive. I concur.

My post started just before #14927. Check out Mariss's posts #'s 14982 and 14988.

If you always used the DC switch first and then close the AC switch, it would likely not harm anything, but if you screw up just once, it may be curtains for the drives.

So let me get this straight- If I shut down the AC side of my DC power supply (28v going into the G320), it won't have any ill effects? But if I open the circuit on the DC side (say, with an E-stop button), it'll destroy the motors?

[Jojje Bergan]

Who talks about the motors?

It's the drives you destroy.

[Crevice Reamer]

Power control. ACM-100 and DCM-100:

http://candcnc.com/

CR.

[LeeWay]

I was talking strictly stepper drives. I know even less about servos.

[Burn]

Who talks about the motors?

It's the drives you destroy.

Ahh, I see. I apologize. Should have looked more closely

[CoAMarcus]

Okay, here is an updated version of the manual. I will be putting some diagrams on there pretty soon, hopefully some time today. I will also try to get the G250 up here, but it is even more diagram dependent because of the 30 pin connector.

The standby is going to be in the next revision, and is not in the current one. I left it in the manual because it was already in there because I just modified a G201 manual and it will have to be in the manual for the REV-4 drives.

-Marcus Freimanis

[Crevice Reamer]

Connect one motor winding to terminals 3 and 4. Connect the other winding to terminals 5 and 6. Turn the power supply off when
connecting or disconnecting the motor. If the motor turns in the wrong direction, reverse the motor winding connections to
terminals 3 and 4.

Shouldn't this be terminals 5-6, and 7-8?

CR.

[CoAMarcus]

That is correct. I changed it in the manual to how it should be. Sorry!

-Marcus

[Crevice Reamer]

The choice of power supply voltage depends on the high speed performance required of the motor; doubling the voltage doubles
the motor’s high speed power. In all cases the power supply voltage should be no less than 4 times or no more than 25 times the
motor’s rated voltage. The motor may not run as smoothly as possible if the power supply voltage is less than 4 times the motor’s
rated voltage. A power supply voltage greater than 25 times the motor’s rated voltage will overheat and damage the motor, even if
it is not turning.

Shouldn't this ALSO warn not to exceed the DRIVE'S maximum voltage?

CR.

[CoAMarcus]

Well, I think that is kind of a given. Just because your car's speedometer goes up to 140 doesn't mean you shouldn't obey the speed limit.

-Marcus

[alipavsky]

Hi Marcus,
You may wish to double-check the temp rating. That 3.50'C may be a bit low.

-Andrey_

[CoAMarcus]

Grrrrrr. Fixed. Again.

Haha, I guess this is what happens when you try to go the lazy route and replace all "7"'s with "3.5" for the current rating. I thought it would replace all standalone "7"'s, but it replaced every single one, even the embedded ones. Our phone number area code became 713.5. Microsoft Word is odd...

-Marcus

[dmauch]

Independent Test Reort of the G251
I have been building 2,3,4 and 5 axis stepper and servo systems since 1996 for an OEM and for individual custopmers. I have been using Gecko drive products since about 2002. I have come to love the quality, simplicity and customer support that Mariss, Marcus, Jan and other at Gecko drive have given me over the years.
As an OEM I was fortunate to be selected to test the new G251 step motor drivers.
Gecko Drives sent me two of the G251 and one of the G250. I install the G251s in one of my smaller 6X10 cases. I used a 10A 33V power supply that I use on various products. The G251's with the screw terminals was very easy to install and wire in that smaller case. The G251 have the built in heatsink and two slotted holes for clamping the heatsink to the base of the case.
After testing the power supply I connected the G 251's and loaded mach 3. I connected two 632 oz in stepper motors that are 8 wires but wired in series for a 3.2A per phase rating. I didn't have the correct set resistors in my vast supply of resistors so I took two resistors and wired them in series for nearly the correct value .
I had a few questions about the preliminary documentation so I called Marcus. He promply answered them. I powered up the system and the little green LED on each board lit up. I used the Tab key on Mach 3 to bring up the MPG and jogged the X and the Y axis in both directions. The motors ran very smoothly. The I went to the MDI window of Mach3 and gave the motors some G0 commands and they ran very fast smooth and with no issues.
Next I did a test that Mariss mentioned in the past. I set the accelleration down real low at .1 in Mach3 and then gave the drivers another G0 command to see how the driver would behave going through the mid band to see how the stabilation performed. It was very good.
I then manually set both motor with the shaft flats facing up and ran a couple torture test programs to see if there were any lost steps. There was none. I ran the drivers for about two hours and by feel could tell that they were barely warmer than abient temperature. Usually without any load on the motors sitting on a bench you will see resonance problems much sooner than installed on a machine. Again I saw no issues.
Last I took the control box out to my shop and connect it my CNC router. The router is a rack and pinion drive set up using 452 oz in motors wired bipolar series for a current requirement of 6A. Even though the G251 were set up with the set resistor to limit the current to about 3A, the motors ran quite nicely. Whereas, the G203 set up for 6A would run the router at 1750 IPM I could only get 1250 IPM for the G251s. Considering that the G251 were running at far less current that the G023's that usually power the cnc router I think that is stellar performance.
Despite their tiny size these baby geckos have awesome performance for their size.
I can't wait unit they finish the deal with the G540 for an all in one package.
Well Done Mariss, Marcus and the folks at GeckoDrives

Dan Mauch
www.camtronics-cnc.com
low cost cases for Gecko drives.
Assembled and tested units
Kits

[tauntdesigns]

Thanks for the review/report.

[High Seas]

I then manually set both motor with the shaft flats facing up and ran a couple torture test programs to see if there were any lost steps. There was none. I ran the drivers for about two hours and by feel could tell that they were barely warmer than abient (sic) temperature.

I am interested in the "torture test" details - maybe calls for a separate thread - but it might be helpful for folks dropping steps with other controllers too.

Very nice report! Thanks, and
:cheers: Jim