Help wiring up BLDC drives with BISSC linear encoder to 6i25_7i76_7i74

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16 May 2024 07:14 - 16 May 2024 10:10 #300716 by pmchetan
Hello,I have Rhino motion controls 400W BLDC motors with hall sensor and supporting 750W drives that I'm planning to use for 3 axes of the CNC mill.

 

 

I'm confused with the PWM input mode and PULSE input mode. 7i76 step and direction signals are pulses right? 

 

TB2P1(GND)        ==>        COM
TB2P3(STEP+)     ==>        SV
TB2P5(DIR+)       ==>        F/R
TB2P6(+5VP)      ==>        5V
Is this wiring right after selecting the dip switches on the drive to enable pulse input? or should I do a PWM input with 7i77 instead of 7i76?
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Last edit: 16 May 2024 10:10 by pmchetan. Reason: Added the motor and drive make

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16 May 2024 11:26 - 18 May 2024 23:51 #300725 by tommylight
Yes, that seems the correct wiring.
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Mesa 7i77 does +-10V, while your drives seem to be 5V PWM, so using a 7i77 would require limiting the output to +5V only, in hal.
Better use step/dir with 7i76.
You can use 6i25 and 7i76 for 5V PWM, does also require tuning and complicates things a bit compared to step/dir.
Edit:
The first line implies that using 7i77 with proper setting in hal can be used as PWM, and that is not correct, sorry for the confusion this might have made.
From PWM to analog can be done with the use of a resistor and capacitor, but not the other way around.
Last edit: 18 May 2024 23:51 by tommylight. Reason: fixing a mess i made.

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16 May 2024 13:57 #300745 by pmchetan
Also I have 6i25 port P2 connected to 7i74 p3 to 7i76. I've asked PCW to make me a firmware with BISS-C for the cards. Should I connect 7i76 with 7i74 with sserial ports in addition to both being connected to 6i25?
He had made a firmware for 5i25_7i77_7i74 before but I had struggled to make a configuration since this card combination isn't available in pnfconf. Making the edits manually is breaking the configuration and linuxcnc won't start. Can you help me with a base configuration for the board combination? I know it is job specific and all configs are different. 

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16 May 2024 17:00 #300766 by besriworld
I wonder these devices can work as a servo driver. Can they change the rpm with a 1khz servo thread.

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16 May 2024 17:43 #300769 by pmchetan

I wonder these devices can work as a servo driver. Can they change the rpm with a 1khz servo thread.

Why else do these cards exist then!! I think they read from encoders at very fast rates 4-6mhz according to the manual. I believe someone has already made closed loop servo drives using just these cards right guys? anyone?

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16 May 2024 17:52 #300771 by PCW
Do you have a link to the drive manual?

It looks rather awkward to control via the SV input
since it seems to be a 0 to 5V signal that needs
a separate direction input (F/R)

It honestly does not look like a servo drive
but rather something more suited to fans or 
pumps etc.

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16 May 2024 18:02 #300772 by pmchetan
robokits.download/downloads/RMCS-6611.pdf

 

This browser does not support PDFs. Please download the PDF to view it: Download PDF



I assumed 7i77's analog signals could be used very similar to an external potentiometer while ordering the drive. They do mention using PLC, PC and modbus for controlling it.
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16 May 2024 19:00 - 16 May 2024 19:01 #300776 by besriworld
If this is the complete guide, it looks like my guess is correct. . .
But let PCW see it too
Last edit: 16 May 2024 19:01 by besriworld.

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17 May 2024 08:04 - 17 May 2024 09:23 #300806 by pmchetan
How can I disable 7i77 encoders to just test the motor drive with open loop?

I did loadrt num_encoders=0  and commented out all encoder feedback lines. I get joint 0 following error.

Is there a way to configure 7i77 without encoder for testing purposes?
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Last edit: 17 May 2024 09:23 by pmchetan.

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17 May 2024 09:41 #300810 by besriworld
It can increase the value of the following error in the ini file . I guess it can work with a very large value.

It can be tested it in an open loop configured as a spindle .

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