M950 K Value Explanation

gloomyandy

@Alijambo73 How are you testing this? Are you sure that the grbl_spd is working with RRF? If not I'd suggest testing it by defining the pin as a standard PWM gpio pin and testing the interface by using M42 to set the pwm value.

Alijambo73

@gloomyandy I have the router conected and try adjusting the speed in the dwc. Would I add m42 below m950? Or are you suggesting using a different pin? Sorry it's been a while since I have had to mess with the config file.

Alijambo73

@Alijambo73 I tested it on the heater 6 pin on the expansion header and it worked as it should but its only 3v . I had it connected to the expansion breakout board on heater 6 pwm pin and it will respond but only between 3.5 and 4.2 volts. I'm thinking the expansion board might be faulty unless there is some config changes for the expansion board that I'm not aware of.

droftarts

@Alijambo73 On the EBoB, you need to invert the output. See https://docs.duet3d.com/Duet3D_hardware/Duet_2_family/Duet_Expansion_Breakout_Board#using-the-servo-headers

Note that the output of the PWM pin is inverted, as it is on the Duex2 and Duex5 expansion board, so any connected servo should have the pin definition inverted. For example, in RRF 3, use:
M950 S0 C"!exp.heater7"
The '!' character in the definition inverts the signal.

Ian

Alijambo73

@droftarts I have tried it both ways with the same result.

droftarts

@Alijambo73 Have a good look over the board, looking for any solder bridges between pins, or poorly soldered connectors. To trace the lines for the heater 6 PWM, see the schematic here: https://github.com/Duet3D/Duet-2-Hardware/blob/master/Duet_Expansion/Expansion_Breakoutv1.1/ExpBreakoutv1.1_Schematic.pdf

Ian

Alijambo73

@droftarts I couldn't see anything and I ra n my meter over the pins to check for continuity. I attached a picture for a different set of eyes.

Let me know what you think ot if I should give up and get a duet 3 6hc.

Thanks

droftarts

@Alijambo73 I can’t see anything on that side of the board. Can you post a picture of the other side?

Does heater 7 pwm give the same output voltages? If so, I expect there’s a problem with the 74HCT chip.

Always happy to sell more Duet boards!

Ian

Alijambo73

@droftarts it does give the same readings. Looks lime a new board is in the future.

droftarts

@Alijambo73 I just realised your board says "Made in China" on the back, so this is very probably a clone board. You can get the genuine Duet board from Filastruder: https://www.filastruder.com/products/duet-expansion-board, with a much higher probability of it working correctly!

Ian