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PWM or analogue spindle control

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03 May 2017 21:29 #92599 by russkinch
russkinch created the topic: PWM or analogue spindle control
Hi everyone. I really hope you guys can assist me. I have built my CNC lathe, all axis working well, limit switches etc. However, I am trying to control the motor (0.75hp 3 phase) with a VFD (Bosch). Now the VFD has modbus as well as 10v options. I am using the Mach 3 BOB which has a pin for 10v control. I really am stuck. I have been through stepconf but have no idea the difference between PWM and PDM, or can someone help me with modbus, I bought a usb dongle. The VFD analogue input picture is attached.

Many many many thanks

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03 May 2017 22:35 #92602 by tommylight
tommylight replied the topic: PWM or analogue spindle control
Use PWM in stepconf, set the values to match your spindle/VFD for max and min RPM, set the pins for CV, CCV and PWM or just leave them as they are for now and move on.
You have to connect the GND and PWM pin from the BOB to the GND and AI1 respectively on the VFD. Set the VFD to have max RPM at 5V ( you can set that to anything from 2-10V on your VFD). You might also need to wire another line for direction but on that later. First make this work, then move on to add other features.
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04 May 2017 11:57 #92629 by russkinch
russkinch replied the topic: PWM or analogue spindle control
Hi. Thanks for the assist. I connected the PWM and GND from the BOB (pins P1 and PCGND respectively) to the VFD pins GND and AI1. Turned all on....nothing. Spindle does not turn with Linuxcnc. In step conf I have set PWM to 50Hz (like on VFD display). Speeds match my motor (max is 1450). However in stepconf, pin 1 says Amplifier enabled. I have set pin 17 in stepconf to PWM, but nothing. Anything screenshots I can send you to help?

Thanks in advance
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17 May 2017 13:05 #93298 by russkinch
russkinch replied the topic: PWM or analogue spindle control
Just a quick update - all working great. The lovely Chinese manual for my borad says...." board can be powered by USB cable or external 24v supply". This is utter nonsense. I thought the difference between 5V and 24V was way too much. I connected the USB cable AND the 24V and the whole other half of the board came to life. The only thing I am still workking on is the spindle indexer, it stops reading at 240RPM and goes to 0. Will look into this later. But for now, spindle operates, lathe operates and after calibrating its only 0.005mm out - way within any normal min and max machining limits.

Thanks to all that offered advice - it was much appreciated.
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