Group: DynoMotion	Message: 9818	From: gabrlarkin	Date: 7/22/2014
Subject: Gecko 203v minimum voltage

I am setting up my KFlop with KMotion, and this is my first experience with the system. I downloaded Kmotion and powered the KFlop with +5v. I am using G203V stepper drivers which are wired with +48vDC, bi-polar parallel to NEMA 34 steppers, I have I/O 8 and 9, pins 15 and 16 on JP7 as step and dir respectively, and I have pin 26 JP7 wired to COM on the Gecko. I am setting output channel to 8 in config/flash.

The problem I am running into is I am only getting 2.84v when I probe step/dir on the Gecko, which requires 3.3v minimum. Another reason I think the voltage is the culprit, is I cannot get the motor to move when I toggle on the I/0. I searched the forums and found similar instances, one time where Tom recommended a step up resistor, which I am afraid to do for fear of harming the board.

Another time, he mentioned configuring the I/O step generator for 3.3v. I can't seem to figure out how to do this. I am getting the sinking feeling that I am missing something obvious or fundamental wrt output voltage.

One thing I tried was several different aux I/0, a few mentioned in forum discussions, and even when I connected to pins that had internal step up resistors I was only getting 2.88v. (I think this was on pins 5 and 6 on JP4 and I changed the output to 0 per forum instructions. I also tried 8, but neither were successful.)

After several hours of trial and error and reading the forums I am out of ideas. Any help is appreciated.

Group: DynoMotion	Message: 9820	From: gabrlarkin	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

I was reviewing the step and direction help page, because I couldn't sleep, so I got out of bed and gave it another crack. No joy.

It would seem to me this quote from the step direction help page is exactly what I need:

Valid output channel settings 0-31 are allowed for KFLOP. Although only 8 Step and Direction generators are available for KFLOP by adding 8 and/or 16 to the channel number the mode of the Step/Dir Generator can be changed.

Adding 8 to the channel number uses the same generator to be used except the output pins are actively driven (high and low) as 3.3V LVTTL signals instead of only driven low as open collector outputs.

So, I went back to config/flash and tried everything again; Channel 0, Input 0, Output 8 (Channel # + 8); pins 15 and 16 to step/dir, pin 26 to common.....2.84v.

I don't understand. The way I am reading the above help guide the step generator should go from open collector to LVTTL signal. But I am reading the same V on 0, 0 as I am on 0, 8. I also tried random channels; e.g. Channel 4 Output 12. No dice.

I am stumped. Must sleep.

Group: DynoMotion	Message: 9821	From: my_triplenet	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

IIRC the step and direction signals IO-8 thorugh IO-15 and IO-36 through IO-43 are 5V tolerant LVTTL outputs that are not going to have much source capability above 2.8V.     The way the G203v is setup you have no choice but to source current into the diodes of the G203V's opto couplers.   It's been a while since I looked at this but I believe the Vf of the input diodes is going to be at least 1.6V, then you have the voltage drop from the 203V's series input current limiting resistor.    At one time I knew the size of the resistor but can't remember and I don't see it in the manual. I would guess it's around 220 ohms.

Most likely the Kflops driver is just running out of drive capability before it can get enough current into the G203V's opto coupler.   You have a couple of options, first the LVTTL outputs have significant excess low drive capability so you could add a pullup resistor to the KFLOPS pin and 3.3V to boost the high side drive, second you could buffer the signals with a true 5V driver.    I don't recommend pulling it up to 5V because it may be possible to forward bias the FPGA's output protection diodes thus driving the FPGA's 3.3V buss above 3.3V and damaging the FPGA.   The pins are 5V tolerant but not sure if this applies to output over drive.

You could try connecting a diode between the G203V and the KFLOPS output pin with the cathode connected to the KFLOPS then add a pullup to 5V on the G203V input pin. The diode effectively turns the KFLOPs output into and open collector and keeps the 5V off the KFLOPS pin. This does reduce the signals noise tolerance and your are more likely to have EMI problems,

I buffer IC is the best solution. Use something with a high Ioh.

I don't like the way the 203V input is seutp the opto couplers should have been a common anode and not common cathode configuration.

Craig

Group: DynoMotion	Message: 9822	From: gabrlarkin	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

Before I get to my_triplenet's respsonse I want to review where I am. Hopefully with the benefit of rest, I can be more clear and succinct.

As before the problem is needing 3.3v for the Gecko 203v.

I have run Channel 0, No input, StepDir output, Input Channel 0, Output Channel 8 on the default bits 8 and 9. So I am connecting JP7 pins 15 and 16 to the step/dir in the Gecko and JP7 pin 26 to the COM. Result: 2.84V.

Now when I try and run bits 8 and 9 in open collector mode, per the instruction in the step/direction help http://dynomotion.com/Help/StepAndDirection/StepAndDir.htm to wit:

[QUOTE]If your amplifier has opto coupler inputs driven off +5V then open-collector mode is likely to work better. The diagram below shows how the open collector mode works driving the LED of an Opto Coupler with the anode connected to +5V.[/QUOTE]

The Digiital I/0 screen toggles the State off on bits 8, 9, so I know the KFLOP is not sending an output signal. This is confirmed with the multimeter. Maybe these pins are LVTTL only? idk

So I goto JP4 which I am pretty sure can be run as open collector:
Channel 0, No input, StepDir output, Input Channel 0, Output channle 0, select bits 16, 17 on the Digital I/0 and the state toggles on. So I am running on opencollector on a pin that has an interal 150ohm pulldown resistor. I am running JP4 pin 5 and 6 as step/dir and JP4 pin8 to COM. result 2.04V.

Same settings running in LVTTL -output channel 8- result: 2.04V

Group: DynoMotion	Message: 9823	From: gabrlarkin	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

Ok, I just got off the phone with Gecko support. He says that the drive needs a minimum of 2.5V not 3.3V, so I it should read 2.8V.

But, he says that I should be reading 0V on step/dir unless I am sending a step/dir signal; IOW I should be reading 0V instead of the 2.8V I am reading when I configur/flash the KFLOP.

He says that it sounds like I need to change my signal to Active HIGH. How do you do that, and does this make sense?

Group: DynoMotion	Message: 9824	From: Tom Kerekes	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

Hi,

I'm surprised the G203V doesn't work with KFLOP's LVTTL output mode. I see that Gecko specs a minimum of 3.3V but I always thought that was meant to imply that they would work connected to 3.3V Parallel ports and such that often only output 2.8V like KFLOP. I have never heard of any issue before. Even +5V TTL outputs are not usually guaranteed to be above 2.8V. So I suspect something else is wrong. Are you sure you have a GND connection?

I also found this in the Manual:

From: http://www.geckodrive.com/g203v-rev-7

The STEP, DIRECTION and DISABLE inputs are opto-isolated. All three inputs work with 2.5V, 3.3V or 5V logic drive signals. The input drive current is now 2.5mA at 2.5V so almost all logic family (74LS, 74HC, etc.) can be used to drive these inputs. The COMMON return for the signals is controller ground referenced instead of +5VDC. This greatly eases the drive to controller interface.

If you really need more than 3.3V you can use a pull up resistor to +5V and open collector output mode. KFLOP 3.3V LVTTL outputs are diode clamped to the 3.3V supply which means they can be safely pulled up to 3.8V. The Step/Dir IO 0-15 on JP7 also have a series 47 ohm resistor to limit current if pulled higher. The clamping diodes can tolerate more than 50ma. But I would limit the voltage to 3.8V or less. I would try a 500ohm pull up resistor to +5V and measure the G203V's Input voltage before connecting to the KFLOP pin.

HTH

Regards

From: "larkin330@... [DynoMotion]" <DynoMotion@yahoogroups.com>
To: DynoMotion@yahoogroups.com
Sent: Tuesday, July 22, 2014 10:28 AM
Subject: [DynoMotion] Re: Gecko 203v minimum voltage

Group: DynoMotion	Message: 9825	From: TK	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

That shouldn't be the issue at this stage.

I suspect you Flashed some wrong configuration to KFLOP. We don't recommend you Flash anything to KFLOP for this very reason. You can set everything back to defaults by Re-Flashing "New Version" on the Config/Flash Screen. Then cycle KFLOP power. Then only set IO 8 and 9 as outputs and toggle IO 8. The voltage should toggle between about 0.5V and 2.8V and the Gecko should microstep.

HTH

Regards

TK

On Jul 22, 2014, at 10:57 AM, "larkin330@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

Ok, I just got off the phone with Gecko support. He says that the drive needs a minimum of 2.5V not 3.3V, so I it should read 2.8V.

But, he says that I should be reading 0V on step/dir unless I am sending a step/dir signal; IOW I should be reading 0V instead of the 2.8V I am reading when I configur/flash the KFLOP.

He says that it sounds like I need to change my signal to Active HIGH. How do you do that, and does this make sense?

Group: DynoMotion	Message: 9827	From: carlcnc	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

203V will NOT run with open collector mode
at least not without some kludging,
you can call and ask them , i did

not bad mouthing them, but the few times I have used 203v I have had issues.
the "protection mode" will often inexplicably trigger on start up and gets worse as you use motors with more than 5 amp ratings during high accelerations
I now use kstep most of the time, if I need more than it's 48v 5 amp I use 201X or protobyte
that said, I have 201 rev 16 that have run for years at 5-7 amps without issue

Group: DynoMotion	Message: 9832	From: gabrlarkin	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

Tom,

Thanks for the prompt reply.

I may be using the word flash incorrectly. All I have done is Download Channel, which I took to mean flash the board.

Regardless, I did as you said and Flashed New Version to the board. Then:

Channel: 0

Axis Modes: Input: No input

Output: Step Dir

Input Channel: 0

Output Channel: 8

Then I pressed Downlaod Channel.

The digital I/O screen cell was left to defaut i/o 8 and 9.

I have the step connected to JP7 15, dir connected to JP7 16, and JP7 26 to COM.

Just as you said when I toggle i/o 8 the voltage toggles between ~.5V and 2.8V. So everything seems to be in order, except no movement. I have my hand on the stepper shaft and I don't feel anything, yet I can plainly see the voltage toggle on my multimeter.

Not sure what the problem could be.

Group: DynoMotion	Message: 9833	From: gabrlarkin	Date: 7/22/2014
Subject: Re: Gecko 203v minimum voltage

Well, since I knew the KFLOP was sending an adequate signal to the Gecko (thanks Tom), and I knew the Gecko had power, the only logical explanation was either the Gecko was faulty from the factory, or I had wired the motor incorrectly.

Yea.....motor was wired incorrectly....lol me. I went over the schematic again and I was reading it wrong.

Loaded everything up and toggled i/o 8 and we have micro-stepping! The neighbors probably think I am going insane as I was literally screaming with joy!

Went to the step response screen cell and clicked move with the default settings.....yahtzee! It's alive!

Thanks for the help and I will update here, and at CNCZone, as I experiment some more. I have a thread on how not to configure the KFLOP for newbies going on CNCZone....I hope it will be helpful to others in the future.

Group: DynoMotion	Message: 9883	From: gabrlarkin	Date: 7/30/2014
Subject: Re: Gecko 203v minimum voltage

Everything has been coming along since my wiring debacle, I am slowly learning KMotion, but I have run into an issue I can't find any guidance on in the forums. When I power on my system Channel 0 engages automatically and starts turning. It doesn't happen every time. The motion it makes is similar to the jog X axis arrow (the slower one) in KMotionCNC.

I have tried powering on with the KFLOP plugged into the PC, with it not plugged in, with it plugged in and KMotion.exe opened, ditto with KMotion.exe not open. As I said it seems sporadic.

I wonder if I am not shutting down the system properly. Following advice I read in some thread, my shutdown procedure is as follows: Close KMotionCNC and KMotion.exe, unplug the USB from the PC, power off (via auxiliary contactor) the control system.

Thanks for any help.

Group: DynoMotion	Message: 9887	From: TK	Date: 7/30/2014
Subject: Re: Gecko 203v minimum voltage

KFLOP should not be driving motors on power up regardless of how things were shut down.

Could you have Flashed some configuration or program into KFLOP? We do not recommend doing so. You can remove everything and return KFLOP to its default state by re-Flashing using the "New Version" button on the Config/Flash screen.

Regards
TK

On Jul 30, 2014, at 11:53 AM, "larkin330@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

Everything has been coming along since my wiring debacle, I am slowly learning KMotion, but I have run into an issue I can't find any guidance on in the forums. When I power on my system Channel 0 engages automatically and starts turning. It doesn't happen every time. The motion it makes is similar to the jog X axis arrow (the slower one) in KMotionCNC.

I have tried powering on with the KFLOP plugged into the PC, with it not plugged in, with it plugged in and KMotion.exe opened, ditto with KMotion.exe not open. As I said it seems sporadic.

I wonder if I am not shutting down the system properly. Following advice I read in some thread, my shutdown procedure is as follows: Close KMotionCNC and KMotion.exe, unplug the USB from the PC, power off (via auxiliary contactor) the control system.

Thanks for any help.

Group: DynoMotion	Message: 9891	From: gabrlarkin	Date: 7/31/2014
Subject: Re: Gecko 203v minimum voltage

I have not flashed anything to the KFLOP. I can reset it just to make sure though.

Now that I am running G Code on my kitchen table I am moving onto the frame; as such I will have several weeks before I install everything permanently so I will have time to tinker with it. I will report back if the issue persists long term.

Thanks for your help.

Group: DynoMotion	Message: 9894	From: Tom Kerekes	Date: 8/1/2014
Subject: Re: Gecko 203v minimum voltage

Its hard for me to imagine how KFLOP could generate continuous Step Pulses without somehow being configured and enabled to do so. But I'm sure stranger things have happened :)

The only other thing that comes to mind is something like poor wiring or grounding that couples something like 60cycle line noise into the Step Signal while it is still yet to be configured and floating.

It shouldn't hurt anything to re-Flash with New Version. In the unlikely event it cause a problem you can recover using the "Flash Recovery".

Good luck

Regards