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PowerPMAC LV with Stepper Motor


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Hi All

I am trying to setup a Stepper motor on a brand new Power Brick LV driver.

The setup is:

- power brick LV, 1.6.0.30, 5/15A

- IDE 1.7.0.53

- RTA stepper motor, 5.6A, 1.9 deg/step, 75V DC max

 

I am following instructions on Power Brick LV preliminary manual (28 May 2014), setting up a stepper motor with encoder, using the stepper as high pole count brushless (p. 122 of the manual).

I followed all the instruction up to the I2T setting, then, proceeding in order with the manual, I should tune the current loop as in the regular brushless motor.

However, I am constantly getting an overcurrent fault ("2 C" on the front led display, because I am working on the second channel), for any current loop test that I perform: "simple autotune" and "auto-tune" always fail, as well as the "Interactive Tune", even if I set a smaller gain and a magnituted of 1 bit on the step size parameters.

 

What I see on the motor is that it get a hit, moves of few degrees, than it stopped with the Overcurrent error.

After that, I can't even recover from the error with teh BrickLV.Reset = 1 command, neither with a soft reset $$$: the only thing that I can do to restore from this error is a hardware power cycle.

 

Do you have any idea on what's happening and how can I tune the stepper motor?

 

thanks

gigi

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Hi

 

It sounds like you might have set Motor[x].PhaseOffset incorrectly, and possibly Motor[x].PwmSf as well. What values do these parameters have, and how did you set them? I recommend going back through the automatic setup for this motor and specifically the Voltage Six Step Test and the Current Six Step Test.

 

I used the value on the documentation, that are fixed for the stepper motor. "Unfortunately" we are on vacation now and we will reopen the office in 3 weeks, I will try to setup the motor with the automatic procedure.

 

Thanks

gigi

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  • 4 weeks later...

Hi

I just updated the firmware to 1.6.1.1, sent a general reset and restarted the configuration.

 

I am using now the automatic System Setup available in the IDE.

I can configure correctly the Stepper Motor to move in Direct-MicroStep, and this is a very good news.

 

Unfortunately, I can't keep the configuration after a reboot (hardware or software).

All the variables are stored correctly (I check them via the Setup Variable panel on the IDE), but after a reboot the motor does not move and I continously get the overcurrent fault (C2 on the led).

Moreover, it seems that the overcurrent fault is latched in hardware: the $$$ is not affecting the state of this fault, as well as a BrickLV.Reset = 1 command; only an hardware power cycle is deleting this fault.

 

Any ideas?

 

thanks

gigi

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Hi,

 

In order to retain your changes you've made through the System Setup software, you need to generate a configuration file, and then copy the changes into a file under PMAC Script Language-->Global Includes in your project.

 

To generate a configuration file, right-click the Configuration folder in your project, and then click Generate Configuration File. This will contain all the changes made from factory default. Copy what you need out of there and paste it into the file you made in the Global Includes folder. You need to download your project at this point, and then issue SAVE, and then the settings will be retained.

 

Regarding the inability to clear the fault, please call technical support to alert them of that issue; call them at 818 717 5656.

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Hi

thanks for the explanation.

 

However, even if the configuration is properly saved on the PMAC, the problem after a reboot is still there.

 

I found this thing that could be interesting: in order to make the motor move after a reboot, I need to go again through the System Setup.

 

The strange thing happens on the System Setup: when I open it, the motor and driver properties on tabs 1 through 6 are all at the correct values; however, if I jump to tab 7 "Test And Commissioning" and I run the automatic test, I got the Overcurrent error.

 

In order to not get the OverCurrent error, I need to go to tab4 "hardware Interface", click on Accept and then I can go to tab7 and run the automatic tests without error.

 

When I click on the Accept button I can see on the Output panel that the Motor properties downloaded are the same that are already in memory; together with the Motor properties it is also downloaded the command BrickLV.Reset = 1.

 

At the moment the system works as expected only if i send a BrickLV.Reset=1 after a power-on, otherwise I got the overcurrent error.

 

Is that behavior nominal? I didn't find any reference on mandatory brickLV.Reset=1 command after power-on on the documentation.

 

Thanks

gigi

 

 

 

 

 

 

In order to retain your changes you've made through the System Setup software, you need to generate a configuration file, and then copy the changes into a file under PMAC Script Language-->Global Includes in your project.

 

To generate a configuration file, right-click the Configuration folder in your project, and then click Generate Configuration File. This will contain all the changes made from factory default. Copy what you need out of there and paste it into the file you made in the Global Includes folder. You need to download your project at this point, and then issue SAVE, and then the settings will be retained.

 

Regarding the inability to clear the fault, please call technical support to alert them of that issue; call them at 818 717 5656.

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The necessity of sending a BrickLV.Reset on power-up, and for clearing fault(s) is well documented in the manual.

 

You should not have any fault(s) on power up. The "no bus" U error code should clear as soon as you bring in bus voltage.

 

Make sure that (as stated in the manual) the:

- Bus voltage is applied after logic

- Bus is brought in by connecting the AC side of the DC power supply, and NOT by bringing in DC voltage. This takes advantage of the rise time of the power supply to avoid the sudden potential step which could cause an over-current, and could potentially harm the electronics.

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