CNC Brain Startup Niggles.

[striplar]

You have reached the end of my knowledge on this I'm afraid. The Device Instance on mine is USB\VID_0FBB&PID_8014\6&18F52E03&0&3 which I guess is a unique system generated ID for that instance of the device. Presumably if you install another CNC Brain on the same computer, you get a different one.
The Driver Version I'm using is 2.11.0.0

Have you tried rolling back the driver? I've never found that to work on anything but there's always a first time!

I have to go now but I'll check back later.
Roger

[Dougal]

Quick update

After uninstalling the phantom usb device, leaving the CNC Brain disconnected from power overnight it has recognised it and allowed me to install the right drivers.

[Dougal]

Right, so I think the driver issue is okay for now. I'll see if it reappears.

Next issue is hunting when jogging.
This morning I could get the x axis to jog forwards and backwards a little. Now I can't.

Even when the drives are powered down, the CNC brain when told to jog shows the position hunting. I'm running steppers open loop.
Are there any settings in the control panel which could cause this?

I also can't get the Y or Z axis to jog, unsure why as the same settings are in for each.

[striplar]

Can I point you to my thread in http://www.safeguardrobotics.com/default.aspx?tab=forum
under "How to... -> Using the CNC Brain with milling M/Cs" section where you will find my thoughts on isolation, earth loops and their relation to instability.

Initially, I would disconnect as much as possible in terms of I/O, encoders and axes you are not testing at that moment to reduce these problems. Swapping the drives round will prove if they are at fault or if there is a problem with the Brain. It's quite possible that one or more tracks are shorted on the Brain because the layout is very fine. I know of at least two boards that were faulty, one being mine. It would be good to test all of the axis outputs on the Brain.

You can alter the pulse width on the Axis tab but I doubt if this is the cause. I had to shorten this to the minimum because of the 1 micron resolution and high speeds I'm using but I doubt if you will come across the same problem.
Other than that, I don't think there's anything there that will affect it.

Are you getting random e-stop messages? These are primarily caused by earthing and isolation issues. The real pain here is the USB connection which grounds the Brain 0V. It's disastrous to have any other connection to earth. This happens as soon as you connect an encoder of linear scale! I know you are running open loop but I inadvertently shorted a 0V on a limit switch to ground and the system was completely unstable. I'm currently using full opto-isolation for ever connection including the USB and the system is pretty solid other than the software issues.

I hope that helps.
Roger

[Dougal]

Can I point you to my thread in http://www.safeguardrobotics.com/default.aspx?tab=forum
under "How to... -> Using the CNC Brain with milling M/Cs" section where you will find my thoughts on isolation, earth loops and their relation to instability.

Initially, I would disconnect as much as possible in terms of I/O, encoders and axes you are not testing at that moment to reduce these problems. Swapping the drives round will prove if they are at fault or if there is a problem with the Brain. It's quite possible that one or more tracks are shorted on the Brain because the layout is very fine. I know of at least two boards that were faulty, one being mine. It would be good to test all of the axis outputs on the Brain.

You can alter the pulse width on the Axis tab but I doubt if this is the cause. I had to shorten this to the minimum because of the 1 micron resolution and high speeds I'm using but I doubt if you will come across the same problem.
Other than that, I don't think there's anything there that will affect it.

Are you getting random e-stop messages? These are primarily caused by earthing and isolation issues. The real pain here is the USB connection which grounds the Brain 0V. It's disastrous to have any other connection to earth. This happens as soon as you connect an encoder of linear scale! I know you are running open loop but I inadvertently shorted a 0V on a limit switch to ground and the system was completely unstable. I'm currently using full opto-isolation for ever connection including the USB and the system is pretty solid other than the software issues.

I hope that helps.
Roger

Thanks for that, I will have a check through earthing later.
But at the moment I have my CNC brain sharing a common earth with my gecko cards and their power supplies. Potential cause right there.

Is there an off-the-shelf optoisolation device which I can use? I'll need about 8 channels I think.

[striplar]

I don't know what's available in New Zealand but I did see an 8 channel board which used ULN2803 drivers or similar driven from something like ILQ74 optos. I'll see if I can track that down.
Here's another less elegant one http://www.industrologic.com/uob8desc.htm that uses rather a lot of chips.

To be honest, I would just knock one up on a scrap of Veroboard, it's really easy to do. That way you get exactly what you want. The two chips I mentioned above would do the job nicely. I used the ILQ74 chip (which has 4 channels) driven straight from the Brain with a 330R resistor in series with the optos. If you need a hand with the detail just let me know what you want to drive and I'm sure you could do this yourself with a little help.

Does your Gecko drive have a separate opto input for each function? I don't know these drives but believe that some have optos and some don't. I also think some have common connections for one side of the opto. The best arrangement is really one that just presents both ends of the opto diode to the user with a series resistor, that way you can connect it any way you like. If you could post a link to the Gecko manual that would help.

[Dougal]

I don't know what's available in New Zealand but I did see an 8 channel board which used ULN2803 drivers or similar driven from something like ILQ74 optos. I'll see if I can track that down.
Here's another less elegant one http://www.industrologic.com/uob8desc.htm that uses rather a lot of chips.

To be honest, I would just knock one up on a scrap of Veroboard, it's really easy to do. That way you get exactly what you want. The two chips I mentioned above would do the job nicely. I used the ILQ74 chip (which has 4 channels) driven straight from the Brain with a 330R resistor in series with the optos. If you need a hand with the detail just let me know what you want to drive and I'm sure you could do this yourself with a little help.

Does your Gecko drive have a separate opto input for each function? I don't know these drives but believe that some have optos and some don't. I also think some have common connections for one side of the opto. The best arrangement is really one that just presents both ends of the opto diode to the user with a series resistor, that way you can connect it any way you like. If you could post a link to the Gecko manual that would help.

The problem for me right now is I tried to build a CNC mill so I could finish some other projects, now the mill has turned into it's own big project.

That board is probably what I'm looking for (I really have no idea). If I can find someone to sell it and post it then I'll get one. Thanks.

[striplar]

You might want to look at this isolator board as an alternative.
http://www.reprap.org/bin/view/Main/Opto_Isolator_1_0
It's only a 4 channel board but you can always use 2 as they are quite small. The opto used on these is very fast and can drive reasonably high loads so would be ideal for things like step & direction.

They actually give the circuit diagram for it on that page and you can buy a kit. If you did that, you could leave off the connectors and solder wires straight into the holes on the PCB if you prefer.

[Dougal]

You might want to look at this isolator board as an alternative.
http://www.reprap.org/bin/view/Main/Opto_Isolator_1_0
It's only a 4 channel board but you can always use 2 as they are quite small. The opto used on these is very fast and can drive reasonably high loads so would be ideal for things like step & direction.

They actually give the circuit diagram for it on that page and you can buy a kit. If you did that, you could leave off the connectors and solder wires straight into the holes on the PCB if you prefer.

Crap, I just ordered the other one.

Are these self-powered devices?

[striplar]

Don't worry, the other one is just fine.

[striplar]

Sorry, I didn't read all your last message.

The inputs to the isolator board are driven by whatever you connect them to. In this case you presumably want to drive outputs from the CNC Brain so you connect the inputs to the pins you need to isolate. The outputs use a common +ve voltage to pull up the output pins. If you scroll to the bottom of this page...
http://www.industrologic.com/uob8man.htm
you can see how it hooks up.
You have to supply this voltage.

[Dougal]

Sorry, I didn't read all your last message.

The inputs to the isolator board are driven by whatever you connect them to. In this case you presumably want to drive outputs from the CNC Brain so you connect the inputs to the pins you need to isolate. The outputs use a common +ve voltage to pull up the output pins. If you scroll to the bottom of this page...
http://www.industrologic.com/uob8man.htm
you can see how it hooks up.
You have to supply this voltage.

Thanks, that cleared it up for me.
I didn't count the pins first time, now I see 33.

I still don't see how there can be soo many different pieces available for these mills, yet no-one puts together a complete kit. There's a major business opportunity for someone selling complete bolt on and plug in kits.

I can buy a CNCfusion ballscrew kit, but I have to workout my own limit switch mounting etc. Some standardisation and integration would go a long way.