Set up of stepper motion control system

[VGA_CD-ROM]

Hi y3k,
That is certainly not expected behavior. I assume you are working within 1-D Interactive Control for your axis? Once you initialize your motor, as the manual says:

To begin a move, click Start or Blend.

To stop the motion immediately, select Halt. To slow the motion to a stop, select Decelerate. To remove power to the axis by inhibiting the amplifier, select Kill.

Halt should stop your motor but still exhibit holding torque. This is most useful in emergency stop situations. Deceleration will only slow the axis down (while still powered) until it reaches a stop, and kill will cut the power and let the axis freewheel to a rest.

Try re-initializing your controller and changing the polarity of the Inhibit Output setting under the Motion I/O Settings for your axis.

[y3k]

Hi there again

The problem was not really solved. Therefore I have attached the settings and configurations of my MAX. I could not seem to control the stepper motor in MAX. Some characteristics of my motor and encoder are:

1) The motor has 200 steps per revolution

2) The encoder has 200 counts per revolution

Would there be any additional infomation you would require in order to find out the root of the problem?

thank you!

Regards

Alvin

[VGA_CD-ROM]

In your Axis configuration page, under the Stepper Settings tab, I see you have your Stepper Output Mode set to "Totem Pole" mode and not "Open Collector". The 7344 series of cards is only capable of Open Collector operation, and the manual for your drive also lists that the Enable (Inhibit) line on the drive normally requies Open Collector connections as well. Try switching that to Open Collector.

Also, I don't know if this is an issue, but you said the motor is 200 steps per rev and on the encoder, 200 counts per rev. However, you have one setting at 400 steps per rev while another page has the encoder set to 800 CPR. Is this intentional?

[y3k]

Hi Vijay S,

Thanks for your reply.

According to the stepper motor, I did a manuel test by turning the stepper motor for 1 revolution. The encoder feedback in MAX showed 800 counts per revolution. Although the encoder manuel mentioned 200 CPR(counts per revolution). I believe the UMI has a quadrupture function. Therefore accounting for 800 CPR.

My set up consists of the UMI7764 and controller 7350. However, I followed the testing the stepper motor in the MAX help guide. In the open loop function, I could not attain basic functions like starting and halting the stepper motor. The motor stops only when the axis is killed. I have connected the ground from the driver to the ground of the UMI and also Enable of the driver to the INHOUT1 of the UMI.

What could be the possible reasons for this? I had set the mode from totem pole to open loop as well. However I still cant halt the motor while its running. However when I set 1000 for following error in 1D interaction advanced tab, the motor runs for 1000 steps and then stops. why is it like this?

Regards

Alvin Tan

[VGA_CD-ROM]

In the Measurement & Automation Explorer help for encoder settings, it says the following about encoder counts per revolution:

If your encoder does not supply resolution in quadrature counts per revolution, determine quadrature counts per revolution by multiplying the encoder resolution in encoder lines or periods by four. Encoder counts per revolution is also referred to as counts per index. For example, a 500 line encoder has 2,000 quadrature counts per revolution.

Is it possible that your encoder's manual listed the counts in 200 periods or lines, leading to the 800 counts per revolution (200 * 4)you are seeing when you test it? The more important thing is that since there is something fundamentally wrong with the way things are working even in open-loop mode, we should ignore closed-loop quadrature feedback for now and continue working in open-loop mode until we get all of that fixed up.

If you try any of the 4 combinations of the S1 and S2 switches on the UMI (up/down, up/up, down/down, down/up), that doesn't clear up your Start/Halt/Kill problem does it? I'll talk to someone in our Motion R&D group about that Kill/Halt issue, but in the meantime, can you give me an exact description of how you have each connection set up from the UMI to your Dragon drive?

[y3k]

Hi there

Thanks alot for your previous reply. I tested the S1 and S2 switches on the UMI. Seems like both must be active low.

Attached are the images of the connections between my UMI 7764 and my dragon driver. Pls take a look.

I would like to ask some questions about variable velocity. How change the velocity of my motor? Will changing the value for the velocity in step/second in motion assistant determines it? How come there are 2 inputs for velocity in 1-D interactive in MAX and motion assistant? Which one determines the velocity?

Thank you

[VGA_CD-ROM]

So the halt/kill functionality is working now that both switches are on Active Low?

As for the motion assistant vs. MAX, the setting in MAX specifies the default operation of the axis when you don't specify the velocity/acceleration/etc. anywhere else. The MAX settings are under your Motion device » Axis configuration » Axis Number » Trajectory Settings, in the Move Constraints tab. This is the target/maximum velocity expected on a move. The settings seen here are loaded when the axis is initialized.

The 1-D Interactive Control and the Motion Assistant are similar in that they allow you to override these MAX axis settings during a move. So if you initialize the axis and simply tell it to move X number of steps in LabVIEW, it uses those settings loaded from MAX. However, when you specify a different velocity in Motion Assistant or 1-D Interactive Control, it overrides the default loaded setting MAX. The new setting will persist until the axis is reinitialized. Think of the 1-D Interactive Control as a separate program like Motion Assistant or a LabVIEW VI that is not directly related to MAX. Settings you change in there will not be reflected in LabVIEW or Motion Assistant, so you'd want to specify your velocities and other move constraint values for each program separately.

And whenever you switch between any programs using an axis (such as MAX, Motion Assistant, or LabVIEW), the axis will have to be reinitialized. That will load up the MAX settings anyway.

[y3k]

Hi

Thanks for the infomation on the velocity.

Both my S1 and S2 switches are on active low. Switching to active high causes the motor to rotate freely.

I think probably there is something wrong with my set up. I changed the velocity in 1-D interactive. However, the "mis plot" shows a constant velocity of 450 steps/s regardless of the input velocity value in 1-D interactive. Would you know what are the possible causes for this situation?

thank you

[VGA_CD-ROM]

Have you switched back to using the stepper in Closed Loop mode with your 200 CPR (or 800 CPR) settings?

Also try switching between absolute and relative positioning modes, and see if much smaller or much larger movements take place at the velocity you expect. If the speed is low only on short moves, the drive may not be accelerating to full speed before it has to decelerate to the end of the move again. Also keep in mind that you might need to adjust the Fast/Slow settings on your drive itself depending on your desired speed. Slow will be needed for 70 steps/s to 5000 steps/s, and Fast for 1800 steps/s to 20k steps/s.

[Qham]

Hi!

Help me to solve my problem.

My labratory has a very old LDV Traverse Table Model 9400 (TSI) which uses 3 stepping motors for moving 3 axes. There is a Position Controller Model 9430 and we still use a Remote Control to control 3 stepping motors.

Now we want to use PC to control this 3 axes tranverse by using Labview. Because on the Position Controller, there is a RS232 input port (25 way), so whether I can conect directly to a usb port of a PC and then use labview to program (we have NI Labview and a compact DAQ).

I have no experience in using labview so please tell me what I have to do. Thanks in advance!