DMU 50M retrofit 99% done, Z axis falling on brake release

radom wrote:

stenly wrote:

Oh, also, my braking/release signal is a single one for all 3 XYZ drives. Is it possible to try and separate them electrically? Most likely. I'm not sure that's a good idea, though.

Now I'm wondering if you are looking at the correct thing
is there anything in the electrical diagram as "Z achse bremse"?

Yes, I probably worded myself confusingly. The *signal* for the brake is a single one for all 3 axes, but the brakes themselves are separate.I am attaching pictures of the electrical diagram that mention it. One is Motorbremze Z-Achse and at the other instance is Reglerfreigabe Z-Achse. Assuming the Regler (regulator) is supposed to interface the brake?

Regarding your other post, thanks for pointing out the relevant part of the docs of the controller. LinuxCNC triggers a following error if my FERROR value is set accordingly, yes. But there seems to be no relation between the following error and how much the axis falls — less than 10mm or so, which the encoder tracks correctly. The drive itself catches it and locks it. From what I see with a multimeter on the Mesa, LinuxCNC tries to compensate for this by sending a crisp 10V to the analog out of the axis to try to get it back into position, but it obviously can't.

If your machine is similar, I'd be curious how you have it set up to power it on in such a way. AC power on does not latch if 6K2.2 CNC-Betriebsbereit (CNC Ready for Operation) is not on. I have said CNC-Betriebsbereit signal linked to halui.machine.is-on so that it triggers when I press F2 power on. After which I can press AC power on and it latches, after which the brake is released.

Is this wrong? Thinking about it, maybe it'd be a good idea not to peg that signal to F2? I will try having the CNC-Betriebsbereit signal linked to something else on LinuxCNC startup, so that F2 can be nothing more but an analog out enable to the drives.

Haha, well, that didn't work. I setp the signal to be 1 at all times. I think I will leave it like that, as I definitely observe the other machine with the original controller NOT dropping it at any moment, even on an emergency stop press. But either way, it didn't help.

I even tried connecting the wire to the 24V power supply directly, so that the signal will always be high no matter what. No result.

Lately what I've been noticing is that the machine is usually capable of starting up the first time, but the axis falls through on trying again after an emergency stop. Is this a clue of some sort?

"Reglerfreigabe" is not brake interface, it is drive enable. That is the signal to enable the muscle power of your servo drives. Could it be that you are releasing the brakes before powering up the drives output stages? That would explain there being no holding torque. Linxucnc sees this Ferror but can't do anything about it as it is commanding a turned off power stage. Seems lucky there is some internal emergency mode in the driver which is catching it after only 10mm. Maybe it does that by ignoring the inactive drive enable, and powering up the output stage to arrest motion?

On my set up, the screw up I made was to enable the drives output stage with the "machine on" signal, but to release the brake when I release my finger from the machine on button, so I had drive fighting the brake for the duration that the button was pressed. 

RotarySMP wrote:

"Reglerfreigabe" is not brake interface, it is drive enable. That is the signal to enable the muscle power of your servo drives. Could it be that you are releasing the brakes before powering up the drives output stages? That would explain there being no holding torque. Linxucnc sees this Ferror but can't do anything about it as it is commanding a turned off power stage. Seems lucky there is some internal emergency mode in the driver which is catching it after only 10mm. Maybe it does that by ignoring the inactive drive enable, and powering up the output stage to arrest motion?

On my set up, the screw up I made was to enable the drives output stage with the "machine on" signal, but to release the brake when I release my finger from the machine on button, so I had drive fighting the brake for the duration that the button was pressed. 
 

Looking at it in this way, the Regler and Bremse being two distinct entities, what you're suggesting may be the case.

However, I do not think I have a signal for the brake itself. The only output signals from the controller to the drives I have are — Reglerfreigabe X-Y-Z Achse, Reglerfreigabe Hauptantrieb, Anwahl Werkzeugspanner, Kühlmittel, ...many empty ones..., CNC-Fehlermeldung, ... many empty ones..., CNC-Betriebsbereit. So that's essentially 5 signals with 29 unoccupied ones.

Do you think there may be a way to interface the brake separately? Right now, it seems that is handled internally by the drive, considering that it releases essentially immediately along with the drive enable — so much so that I had thought they were both one singular operation. An internal servo parameter? But I didn't find any brake related parameters in the doc. I do see some BR1 and BR2 signals in the Vorschubantrieb page (attached). I will investigate.

stenly wrote:

RotarySMP wrote:

"Reglerfreigabe" is not brake interface, it is drive enable. That is the signal to enable the muscle power of your servo drives. Could it be that you are releasing the brakes before powering up the drives output stages? That would explain there being no holding torque. Linxucnc sees this Ferror but can't do anything about it as it is commanding a turned off power stage. Seems lucky there is some internal emergency mode in the driver which is catching it after only 10mm. Maybe it does that by ignoring the inactive drive enable, and powering up the output stage to arrest motion?

On my set up, the screw up I made was to enable the drives output stage with the "machine on" signal, but to release the brake when I release my finger from the machine on button, so I had drive fighting the brake for the duration that the button was pressed. 
 
Looking at it in this way, the Regler and Bremse being two distinct entities, what you're suggesting may be the case.

However, I do not think I have a signal for the brake itself. The only output signals from the controller to the drives I have are — Reglerfreigabe X-Y-Z Achse, Reglerfreigabe Hauptantrieb, Anwahl Werkzeugspanner, Kühlmittel, ...many empty ones..., CNC-Fehlermeldung, ... many empty ones..., CNC-Betriebsbereit. So that's essentially 5 signals with 29 unoccupied ones.

Do you think there may be a way to interface the brake separately? Right now, it seems that is handled internally by the drive, considering that it releases essentially immediately along with the drive enable — so much so that I had thought they were both one singular operation. An internal servo parameter? But I didn't find any brake related parameters in the doc. I do see some BR1 and BR2 signals in the Vorschubantrieb page (attached). I will investigate.
 

I'm coming to the conclusion that the Regler power on electrically triggers the brake release. In the page I've attached, that's what it seems like. So it is probably not possible for me to interface them separately. Then again, the brake release having the regulator (7K2) as a prerequisite, should ensure the brake isn't released without the drive being powered on, no?

Regler (DE) = servo driver module (EN). On my machine it is the Indramat, on yours it is the Simodrive 611.

7k2 is not the servo driver is it? DMG terminology would be that 7k2 is a 24V control relay. On my machine the servo drivers (the indramats) are called 7A1 and 7A2. On yours the Z axis drive is 7A5 (you probably have three separate servo drives on the axis, another on the spindle, and maybe a fifth on a C axis? I only have two.

The brake releases as soon as the 7K2 relay closes. What is the signal chain which energises the 7K2 coil? That needs to happen at the same time as the Reglerfreigabe is commanded through the X331 terminal block on your Simmodrive.   What are the three signals in the X331 terminal block? I would guess the Reglerfreigabe signal , a gnd and maybe the third wire in that cable is a "driver enabled" feedback to the CNC controller. Alternatively, it could be a "Servo Drive Fault" signal.

How did you tie them into LinuxCNC? You need to be setting whatever pin in X331 is the drive enable to active, at that same time as you are energising the 7K2 relay.

RotarySMP wrote:

Regler (DE) = servo driver module (EN). On my machine it is the Indramat, on yours it is the Simodrive 611.

7k2 is not the servo driver is it? DMG terminology would be that 7k2 is a 24V control relay. On my machine the servo drivers (the indramats) are called 7A1 and 7A2. On yours the Z axis drive is 7A5 (you probably have three separate servo drives on the axis, another on the spindle, and maybe a fifth on a C axis? I only have two.

The brake releases as soon as the 7K2 relay closes. What is the signal chain which energises the 7K2 coil? That needs to happen at the same time as the Reglerfreigabe is commanded through the X331 terminal block on your Simmodrive.   What are the three signals in the X331 terminal block? I would guess the Reglerfreigabe signal , a gnd and maybe the third wire in that cable is a "driver enabled" feedback to the CNC controller. Alternatively, it could be a "Servo Drive Fault" signal.

How did you tie them into LinuxCNC? You need to be setting whatever pin in X331 is the drive enable to active, at that same time as you are energising the 7K2 relay.
 

Thanks for sticking with me through this. B and C are nothing but encoders, their movement is done manually by the operator.

I have a separate main drive for the spindle, a separate drive for Z and XY are on one drive. This, in addition to the control module with the 7 segment display.

I believe X331 contains the Sollwerte and the Reglerfreigabe. The Sollwert has 0V and ±10V connection, so that should be three. The Reglerfreigabe signal links to a different page where it shows it on an Interface Regler and the signal is listed as Kl.65 or 65.1. That in turn is dependent on 7K2. (page attached)

Yes, 7A5 is the Z Regler and 7K2 is its Freigabe relay, right? I believe 7K2 is energized only by the single output signal on X41 (attached page). The other 4 references to it show where its output goes. Regarding how I link that to LinuxCNC, I certainly am not linking the X331 signal to the Mesa directly. I don't see an obvious way to, nor do I think it initially went into the Heidenhain controller. From the looks of it, the signal on X41 that energizes 7K2 relay should be what handles the X331 Reglerfreigabe. It looks to be sequential, meaning X331 will be set after 7K2 closes. Am I understanding this backwards?

I took another look at my Maho's schematics. Seems similar except my 7K2 relay control is hardwired into the "machine on" latching circuit rather than being directly controlled by the CNC.

 

 

Because this is a hardwired signal chain, E-stop drops K1, breaking the chain and therefore dropping 7K2.


So on your set up, LinuxCNC connects to X41 and controls the 7K2 relay, which similtanously enables the drives and releases their brakes. If that is the case, then I have no idea why your axis is dropping, as the Zaxis is getting enabled at the same time as brake release.
Since you suspect a correlation with E-Stop, could it be that E-Stop is not dropping 7K2, leaving the brake off, but some other signal deactivates the drive, so you end up with brake off and no torque? Basically your more modern controller was replacing the hard wired E-Stop chain with some software PLC functionality which you haven't duplicated in LinuxCNC yet?

 

Reasonable suggestion. I will dedicate some time tomorrow to extensively analyze and measure what 7K2 does and how it behaves when machine is on, off or with e-stop pressed. I should probably try to see if swapping the X and Z drives won't achieve something. Thank you again, I will post my findings.

Don't try swapping drives. At least on mine, the Z axis motor is larger for the extra force to fight gravity, so the drives, PID values etc are all different. I would doubt that there is a problem there. Sounds like a LinuxCNC configuration issue.