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Lost connection

Posted by Fabiano 
Lost connection
May 03, 2012 11:02AM
Hi.

I am new to reprap and just 2 days ago finished building my prusa mendel.

I am having 2 issues that are stopping me from printing anything:

1. The softwares disconects from my printer when I am trying to move a motor, sometimes is the 1st click to move 10mm and sometimes it moves all motors ok but when I sent a model for dry run it does some movement and stops. I am not able to do even a 1x1x1cm cube dry run print all the way to the end. If I unplug say the Z motors it seems to do the job.

2. I also cannot get the Heater to work. When I try to turn the Heat On the red LED flashes and the printer disconnects.

Any suggestions?

This are my specs at the moment:
* Prusa Mendel
* Generation 6 Elec.
* Latest Repetier firmware and Host for MAC (0.16)
* Z motors wired on parallel
* Baudrate 250000

Thanks in advance.
F.
Re: Lost connection
May 03, 2012 12:39PM
Your setup is exactly the one I used to develop the software, so it should work with minimal changes like steps per mm.

From your description I guess your power connection is not stable. Every time you draw more current you seem to loose connection. You should have a closer look at the log output. If you see a start after your connection loss, the hardware did a reset for some reason. That normally
happens if your voltage goes below a certain treshhold.


Ordbot + iRapid + Mendel
Repetier-Software the home of Repetier-Host (Windows, Linux and Mac OS X) and Repetier-Firmware
Re: Lost connection
May 03, 2012 01:23PM
Thanks for the reply.

I have a felling is a power shortage as well, but I cannot figure it out.
My power supply is a brand new ATX 200W and the voltage is 12V solid.
Also all the TP1, TP2, TP3 and TP4 little dials on the board are all set on the middle.

Do you think I could increase the power input above 12V?

Also I have attached a Log file of my last run, don't know if can be of any help.
F.
Attachments:
open | download - 20120503_Log.rtf (3.1 KB)
Re: Lost connection
May 03, 2012 02:32PM
Don't go over 12v unless you know what you are duing. This could easyly blow your extruder heater.

You could try adding a fan or some other load on 12v. Some Atx supplies need a basic load or they will turn off. Could also be your problem, but i think you have simly connected the 12v to the board? Should be enough load to keep it on.

Regarding your log, i saw a real disconnect. I think the FTDI chip really closed the connection. With stable voltage this normally neverh apens. Even with a reset on the board you don't get a disconnect. So the connection itself could also be the problem. So some other tests you cold do

1. Unplug motors and do a dry run
2. Use a different USB cable.


Ordbot + iRapid + Mendel
Repetier-Software the home of Repetier-Host (Windows, Linux and Mac OS X) and Repetier-Firmware
Re: Lost connection
May 03, 2012 03:54PM
Hi Fabiano.

200 Watts seems very low. Can you tell us what the 12V amps rating is on the supply? It should be on the label somewhere.

If you have less that 18 Amps@12V, you might run in to trouble because the power supply voltage will collapse.

Also, if your hot end has a short, or the resistance is really low (say less than 5 Ohm) you will draw more amps than the supply can sustain.

If you want to play it safe, get a used supply with at least 23 Amps, or buy one of the PSU that Lulzbot.com sells.

-Wildseyed-
Re: Lost connection
May 03, 2012 04:10PM
Hi.

My power supply is 12V but max of 10Amps and my Extruder Heat and Thermistor are these?
Extruder Heat
Thermistor

I am currently doing some tests and I will give a feedback in 30min or so.
Thanks.
F.
Re: Lost connection
May 03, 2012 05:04PM
Repetier.

After trying your suggestions this is the outcome:

Dry Run with NO motors connected:
I did 5 runs and it worked 100% of the time.

Dry Run with ONLY the X, Y and Z motors connected:
It did not work at first, same problem as before (connection closed).
Then I found something out if I run the motors once, even 0.1mm, just to switch them on then turn them off and press FAKE OK, I can make then work without any errors. I did 10 consecutive runs and they all worked.

Dry Run with everything plugged in:
Same as before. It fails if I just switch the board on and run the job without pressing FAKE OK before.

Run with no filament and with a very small LED Resistor (temp. for run set at 15 degrees Celsius):
X, Y and Z engines working and the Extruder engine makes more noise than it actually turns. Need to hit the FAKE OK before run again.

Run with no filament and with the 6.8Ohms Resistor:
Red light on the Gen 6 board flashes once and I get a "1 Commands waiting" at the bottom parts of the window. The printer stays as connected at the host software but I cannot give it any more orders and I need to close the connection and reconnect.


So it looks like either the Resistor its drainning all the power from the power supply and shutting down the board or my connection to resistor is not done properly.
Furthermore the Extruder motor seems to be very moody and sometimes it works wonder and sometime it just makes noises but does not rotate...power supply again?
JCabrer pointed out I need a 12V with at least 18Amps as a power supply. I will try to find one tomorrow and give it a go.

F.
Re: Lost connection
May 04, 2012 12:09AM
Fabiano Wrote:
-------------------------------------------------------
> Repetier.
>
> After trying your suggestions this is the
> outcome:
>
> Dry Run with NO motors connected:
> I did 5 runs and it worked 100% of the time.
>

So the cable is ok and it is no software problem as far as it depends on motors.

> Dry Run with ONLY the X, Y and Z motors
> connected:
> It did not work at first, same problem as before
> (connection closed).

The firmware runs the same code but the load causes the problem.

> Then I found something out if I run the motors
> once, even 0.1mm, just to switch them on then turn
> them off and press FAKE OK, I can make then work
> without any errors. I did 10 consecutive runs and
> they all worked.
That is strange. Fake OK assumes the ok was send signaling a command was received. This has absolutely no effect on the firmware. It is to compensate a lost OK from the firmware. Perhaps enabling the motor causes a voltage drop enough to cause communication problems but not enough for a connection lost. Thats the only thing that makes sense to me.
>
> Dry Run with everything plugged in:
> Same as before. It fails if I just switch the
> board on and run the job without pressing FAKE OK
> before.
>
> Run with no filament and with a very small LED
> Resistor (temp. for run set at 15 degrees
> Celsius):
> X, Y and Z engines working and the Extruder engine
> makes more noise than it actually turns. Need to
> hit the FAKE OK before run again.
>
> Run with no filament and with the 6.8Ohms
> Resistor:
> Red light on the Gen 6 board flashes once and I
> get a "1 Commands waiting" at the bottom parts of
> the window. The printer stays as connected at the
> host software but I cannot give it any more orders
> and I need to close the connection and reconnect.
>
>
> So it looks like either the Resistor its drainning
> all the power from the power supply and shutting
> down the board or my connection to resistor is not
> done properly.
> Furthermore the Extruder motor seems to be very
> moody and sometimes it works wonder and sometime
> it just makes noises but does not rotate...power
> supply again?
> JCabrer pointed out I need a 12V with at least
> 18Amps as a power supply. I will try to find one
> tomorrow and give it a go.
>
> F.
The sounds from your extrude rmotor are lost steps. Either because you have filament inserted with only 15 degrees celsius, the motor blocks or

#define EXTRUDER_SPEED 18

is set to high. My maximum is 18. I'm working on an update where acceleration is used, so extruder speed can be increased. But for now reduce it until your motor doesn't lose steps any more.

Ams needed is not that high if you have no heated bed connected. With 6.8 Ohm for heater you need at maximum 12/6.8+4*1.5=7.8A Round it up to 8A you need 10*12 = 96W on the 12V voltage line. Look at the specs of your ATX. The 200W is for all voltages so the chance is high 12V delivers less then this. With heated bed on 12V you come fast to the 18A JCabrer told you. And with ATX power look which wire can deliver how much current. Not sure how the atx really works, but you may need to combine the power lines to get full power if they are created in separate parts of the supply.


Ordbot + iRapid + Mendel
Repetier-Software the home of Repetier-Host (Windows, Linux and Mac OS X) and Repetier-Firmware
Re: Lost connection
May 04, 2012 12:54AM
Have you got a dummy load on the 5V rail? 99% of PC PSUs will not work properly without one and shutting down is one of the symptoms.

Another thing it could be is a poor ground connection between the board and the power supply. It should be short and thick. If not motor and heater current can flow though the USB cable ground and that can disrupt the comms. Because USB is a connection oriented protocol it will not recover from a lost connection without host intervention.

Edited 2 time(s). Last edit at 05/04/2012 01:32AM by nophead.

[www.hydraraptor.blogspot.com]
Re: Lost connection
May 04, 2012 01:50AM
Hello again.

I just changed the Extruder_Speed from 20.0 to 18.0 and to 10.0 and it does the exact same movement. I have uploaded a video of the problem. Notice how the extruder kind of moves forward and then backwards when I hit Extrude:

Extruder Problem (MOV)

Also about the Amps on the ATX. It says 10A for the +12V, everything else is lower then this value.

Currently I do not have a Heated Bed attached to the power supply, so its just 3 OPTOS, 5 NEMA-17 Motors, Thermistor and Heat Resistor...

Thanks again.
F.
Re: Lost connection
May 04, 2012 01:56AM
Nophead.

I am not very knowledgeable on electronics, so I didn't quite get your reply...sorry.
My PSU is connected to the Gen6 via a single set of yellow/black wires. Nothing else is attached to it.

Here is an IMAGE of the ATX-Gen6 connection

Any advise is appreciated.
F.
Re: Lost connection
May 04, 2012 01:57AM
I had the same effect once and it was a pin not connected correctly to the board. That way I lost one magnet direction and it didn't turn. I'm not sure what happens when polarity of one pair is changed in direction. I guess it will only change turning direction.


Ordbot + iRapid + Mendel
Repetier-Software the home of Repetier-Host (Windows, Linux and Mac OS X) and Repetier-Firmware
Re: Lost connection
May 04, 2012 02:07AM
Repetier.

Bingo. Re-wired and its working.

Thanks again.
F.
Re: Lost connection
May 04, 2012 02:07AM
What nophead meant is that a normal computer where the atx normally belongs to has a basic load on 5v line (Red wires to GND). So add a 100 Ohm resistor between red and gnd to simulate basic load. Make sure no free leads are hanging around when you do so. Without this basic load the 12V line may get disabled. In addition the sense pin must be connect to ??? to get it enabled, didn't see what you did with that wire. Perhaps it is better to take the 12V from the 2x2 12V pin header and bind the two 12V wires together? They are meant for high 12V loads and your comes from a HD connector. If they all come from the same contact in the atx this makes of course no difference.


Ordbot + iRapid + Mendel
Repetier-Software the home of Repetier-Host (Windows, Linux and Mac OS X) and Repetier-Firmware
Re: Lost connection
May 04, 2012 02:50AM
Repetier.

Ok I will try that and give you a reply in a few hours...

One more thing before I go. IF the problem is the Amps what If I take X, Y and Z motors and the OPTOS, leaving just the Extruder Parts connected to the board, my 10A@12V should be able to run the Heater. Correct?

I just tried that and it does the same thing LED 3 Flashes once and Conneciton Lost.

Thanks in advance again.
F.
Re: Lost connection
May 04, 2012 02:57AM
Fabiano Wrote:
-------------------------------------------------------
> Repetier.
>
> Ok I will try that and give you a reply in a few
> hours...
>
> One more thing before I go. IF the problem is the
> Amps what If I take X, Y and Z motors and the
> OPTOS, leaving just the Extruder Parts connected
> to the board, my 10A@12V should be able to run the
> Heater. Correct?
>
Yes.
> I just tried that and it does the same thing LED 3
> Flashes once and Conneciton Lost.
>
Well if nopheads comment fits on your ATX like the othe 99% this was to expect. I think what the ATX does is it gives you very little power for some standby operations. As soon as you need more power it wants the basic load. You should also look into the reprap wiki. There is a longer article on connecting atx to printer boards.


Ordbot + iRapid + Mendel
Repetier-Software the home of Repetier-Host (Windows, Linux and Mac OS X) and Repetier-Firmware
Re: Lost connection
May 04, 2012 03:47AM
10A should be plenty to run everything apart from a heated bed.

You need a load on the 5V rail (red and black). Something like a 10R power resistor or a 12V car light bulb.

I would also shorten the 12V connections and use at least two black and two yellow wires. That is tricky though as it looks like the gen6 has an inadequate power connector. I would replace that with screw terminals.

USB is not very tolerant to ground noise in my experience despite being differential signals.


[www.hydraraptor.blogspot.com]
Re: Lost connection
May 04, 2012 07:00AM
10 Amps MIGHT be enough. Part of it depends on how many powered devices are running.

Five Stepper Motors (how high is the current adjust on each of the stepper drivers?)
Z-Stepper motors configured in firmware to remain powered when not moving draws more current
One Fan/Two Fans/No Fans - Some fans draw more currnt than others.
Any lights being used to pimp out the printer
Extruder (what is the heater resistor Ohm value?)

I would encourage you to find a larger capacity PSU. Having more Amps to work with eliminates any doubts, gives you more flexibility on adding options like the heated bed, and the bigger capacity may result in a longer time before PSU failure, although any PSU can fail at any time.
Re: Lost connection
May 04, 2012 11:26AM
No 10A is plenty without a heated bed. My Mendel only takes 6.4A and I run the motors hot, have three fans and some lights. Don't forget the stepper drivers take less supply current than they deliver to the motor.


[www.hydraraptor.blogspot.com]
Re: Lost connection
May 04, 2012 12:08PM
Hello to all.

After insulting myself and the power supply several times I did the dummy connections on the red/black yellow/black cables using a 12V car lamp.

The weird thing is, and probably the one and only problem after all, it that both lamps are pulsing.
I saw in another post someone with the exact same problem and nophead said something about connection red to black wires, etc. Again, I am not very wise on eletronics and learn better by looking at something.

The way I set up my ATX is that I plug the green and grey wires on the switch at the back so that I have an external power on button. Don't know if this is the problem. If so could you please advise? Here are some pics.

Dummy
Connection

Thanks again.
F.
Re: Lost connection
May 04, 2012 12:45PM
Nophead.

I just managed to fix the pulsing light and I was able to turn the 6.8Ohms Extruder Heater.
I did a quick run (without filament) but with all motors on and the result was good....well, sort of.

The Heat Resistor immediately starting to smoke and turn black.
Is it something to do with the power supply of is my wiring wrong, etc...

Thanks again.
F.
Re: Lost connection
May 04, 2012 05:08PM
To turn on the PSU you should connect green to black, not grey. When you connect green to grey it will pulse because grey is the power good signal. When power is is off the PSU turns on until power good says it is up to spec and then it turns off again.

The heater resistor should be inserted into a heater block in a way that makes good thermal contact. If you simply had a naked resistor it would smoke and burn because it is severely overloaded. It works in the heater block because that acts as a heatsink greatly increasing its power handling ability. Also is must be a vitreous enamel resistor which are able to withstand 350C. Any other type will burn.


[www.hydraraptor.blogspot.com]
Re: Lost connection
May 04, 2012 09:41PM
Thanks everybody for the help. Really appreciate it.
Its hard to figure things out when you never even seen the machine in person.

After all it was just a question of wiring back inside the PSU. The dummy is not required to run the machine (at least in my case), but it helped me get to the problem and learn a few more things about how all of this works.

Now I need to work on the extruder block to get the thing to ready the desired temperature.
Thanks again everyone.

Case closed.
F.
Re: Lost connection
May 05, 2012 01:17AM
It may not cut out without a dummy but the the 12V rail usually drops to about 10.4V when you load it heavily without a load on the 5V rail.


[www.hydraraptor.blogspot.com]
Re: Lost connection
May 05, 2012 01:44AM
So should I keep both dummies, one on the 12V and one on the 5V, or just the one on 5V?
F.
Re: Lost connection
May 05, 2012 03:48AM
Just a dummy on 5V as you have a real load on 12V.


[www.hydraraptor.blogspot.com]
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