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Author Topic: Pokeys57cnc 10v spindle control only reaches 8.1v  (Read 9499 times)

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Pokeys57cnc 10v spindle control only reaches 8.1v
« on: December 23, 2016, 10:04:00 PM »
Just finished building a Routakit and fit a Pokeys57cnc to it. Tonight I tried to connect the Huanyang VFD to the board. The relay turns it on and I finally got speed control but not full RPM and it is VERY non-linear. First, symptoms.

S24000 only gets me 20200 RPM, voltage reads 8.1v. S12000 produces 13200 with 4.0v. S6000 is 11000RPM and 2v. So far linear voltages but not VFD response (I'll look into the VFD after I solve the voltage). Then it gets screwy. S3000=9000RPM and 1.4v. S1000=13000RPM with voltage back UP to 4v. If I close Mach4 and use the Pokeys utility and move the PWM slider, same voltage profile is output 0% is 4v, 25% is 2v, 50% is 4v and 100% is 8.1v. In Mach4 diagnostics of the Pokeys plugin, the monitor box tracks correctly from 0% to 100%, but shows it on pin 18 for some reason. All spindle settings are set to pin 17 as spindle control. Board power is from a 24v 5A "laptop" type supply and the jumper is set to EXT for power. I have measured the voltage at both the VFD and Pokeys end and even disconnected the 10v wire and measured output. Ground wire is connected to GNDi and I tried both terminal 1 and 4 for GNDi. Mach spindle settings have been varied with no change in results (i.e. range 6000-24000, 0-24000, PWM frequency varied from 800 to 20000. HELP

Jason
Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #1 on: February 11, 2017, 10:30:28 PM »
Did some experimenting and when I disconnect the VFD from the Pokeys, the voltage output behaves like it is supposed to. It is when the VFD is attached that the Pokeys output gets messed up. Is this ground loop? What would be a solution to try?

Offline NeoTO

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Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #2 on: February 25, 2017, 01:32:14 AM »
The analog output is galvanically isolated and can handle limited amount of current (<50 mA). Check the input impedance of the VFD's analog input.
www.poscope.com home of PoKeys USB HID, IO, USB, Ethernet controler and PoScope USB PC oscilloscope
Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #3 on: February 25, 2017, 12:55:29 PM »
With the VFD on and the jumper set to remote speed control, the impedance of the VI terminal and analog ground terminal is 19.9K ohms
Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #4 on: February 27, 2017, 02:42:26 PM »
sorry I see you have played with pwm but have you actually used the voltage trim pot on the card?

Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #5 on: February 28, 2017, 11:17:37 AM »
Yes, the output is 10v at 100% if I don't connect the VFD. When the VFD is connected it goes to 8.1 max. If I trim it up to 10v I can get full speed but the slowest it will go is 9000 rpm, and thats at 25%. Lower percentages than 25 start giving higher voltages and speed increases.

Offline NeoTO

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Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #6 on: March 05, 2017, 02:26:12 AM »
Do you have any other loads connected to PoKeys device?
www.poscope.com home of PoKeys USB HID, IO, USB, Ethernet controler and PoScope USB PC oscilloscope
Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #7 on: May 18, 2017, 08:53:34 AM »
I've the same problem. I could set the rpm in mach4 "spindle" "min and max rpm" to adjust the outputvoltagespektrum of the pokeys57cnc. The rpm area isn't as big as needed.  I can start from 9000 to 22000. i've used the pot too. regards
www.cncprint.blogspot.com

Offline NeoTO

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Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #8 on: May 19, 2017, 12:52:59 AM »
How do you power the PoKeys57CNC device?
www.poscope.com home of PoKeys USB HID, IO, USB, Ethernet controler and PoScope USB PC oscilloscope
Re: Pokeys57cnc 10v spindle control only reaches 8.1v
« Reply #9 on: May 19, 2017, 09:22:44 AM »
I power it directly with a 24V wall plug.
regards