Reach Mechanical Index

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kevalvirani
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Joined: Fri May 04, 2012 6:48 am

Reach Mechanical Index

Postby kevalvirani » Sun Aug 25, 2013 6:21 am

Hi,
We have CRD507-KP controller and motor with US digital 500 CPR Encoder with index. I studied your documentation to read the encoder index (I have bought the complete package including Harmonic Gear motor, Encoder and controller) but unfortunately can't find out method for it.
All the pins are connected to CN5, so there should be some method to get it from the controller/Driver it self.
So kindly advice me in detail to read enocder index.

Regards,
Keval Virani.

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om_tech_support_JT
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Re: Reach Mechanical Index

Postby om_tech_support_JT » Thu Aug 29, 2013 4:23 pm

Hi kevalvirani,

Thank you for using our stepper motor systems.

After you connect our included encoder to the CN5 connector on the CRD507-KP driver with built-in controller, you'll need to set up the encoder on the Immediate Motion Creator GUI software. Have you done this yet? Does the GUI already read the A and B phase pulses from the encoder? If so, skip down to the 1st forum article below.

Once you set up the encoder resolution on the GUI, the FEEDBACK POSITION value on the GUI should start to update as the motor rotates. Enable either the STEP OUT function or the SELF CORRECTION function to allow the system to maintain itself.

Here are some other forum articles that may be helpful:

Using the Encoder's Z signal to Increase Homing Accuracy
viewtopic.php?f=18&t=590

Self-Correcting Function on the CRK Stored Program Driver
viewtopic.php?f=18&t=527

kevalvirani
Posts: 6
Joined: Fri May 04, 2012 6:48 am

Re: Reach Mechanical Index

Postby kevalvirani » Mon Sep 02, 2013 1:35 am

Dear Sir,
Thank you very much for your reply,
I checked that I am able to read Feedback position as I move motor. And I have connected my Encoder to CN5 as per the instructions.
And as per your instructions set timen =2 and then I initiated homing position from CRK Motion Controller.
In this case, motor doesn't stop rotating by reaching Mechanical Index neither the counters (command, feedback) gets resetted to 0.
So How can I identified when encoder home reached ?
Please give me example in detail, so I can implement the solution easily ?
Here do we need any other sensors to seek mechanical home position ?
Also, I tried Example given on page 48, but no luck.
Am i Missing something ?

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om_tech_support_JT
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Re: Reach Mechanical Index

Postby om_tech_support_JT » Tue Sep 03, 2013 3:10 pm

Hi kevalvirani,

Yes you do need to connect an actual home sensor wired to the CRK stored program driver in order to have it perform a successful mechanical home seeking operation. It's not designed to seek home according to an index pulse from the encoder; although it can be set up to do so. It's designed to use an encoder's index pulse in addition to a home sensor signal in order to provide a more accurate mechanical home position.

The CRK stored program driver allows you to do 2 types of homing operations in order to move the motor to its mechanical home or electrical home. A mechanical home is where the physical home sensor is. An electrical home is where the encoder count is at zero. If you do not have a home sensor connected to our CRK stored program driver, then you can only do an electrical home seeking operation.

The fact that you can read encoder pulses correctly tells me that your encoder has been wired correctly.

Did you initiate your mechanical home seeking operation from the CRK Immediate Motion Creator GUI software - MOTION CREATOR tab? Did you click on "Go Home Pos" or "Go Home Neg"? If so, these can only perform mechanical home seeking operations.

The easiest way to do an electrical home seeking operation is to add the following command lines into your program, or type them in the TERMINAL tab.

DIS 0
MA
(Add speed parameters as needed: VR, VS, TA, TD)

We're basically setting the DIS distance value to 0, which is the actual electrical home position where the pulse count is zero, then we're doing an MA absolute move command which moves the motor to exactly 0.

The CRK stored program driver is designed to seek an electrical home position with its internal pulse counter. If you want to seek home with the Z or index channel pulse from the encoder, you'll need to wire the Z or index pulse from the encoder to the CRK driver's home sensor input and use 3-sensor mode for home type (HOMESEL=1).

Please let me know if you have any more questions. Hopefully this helps.

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Re: Reach Mechanical Index

Postby om_tech_support_JT » Tue Sep 03, 2013 3:17 pm

FYI:
1. Speed parameters (VS, VR, TA, TD....etc.) need to be added before the move command (MI, MA, MGHP, MGHN, MCP, MCN....etc.). If you add the speed parameters after the move command, then it will not execute properly.

2. When a mechanical home seeking operation is finished, the CRK stored program driver will establish the new home position as its electrical home position (it will also reset itself once power is cycled).


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