Mis placed thred

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22 Nov 2019 13:04 #150910 by jools
Mis placed thred was created by jools

PCW wrote: - Should the default and resting PWM voltage not be 0V?

It is, if you measure STEP4+ relative to ground
Note that STEP4+ will be at +5V before LinuxCNC starts so you need to have a
separate spindle enable (you can avoid this issue by using STEP- and inverting the
PWM pin in HAL)

- For me I am using it to drive a spindle servo - Should I offset my spindles 'stop' voltage so that it thinks -5v is 0V?

No need, this is a wiring issue

- Or should linuxcnc use it's 'offset' function to adjust this internally

No need

- PWM type=2 (up and down) does not seem to work on this. Maybe because of the -5v at stop issue above it can't go lower for reverse.

PWM type 2 does work (but probably not in the way you think)

For normal PWM (type 1) the PWM value is the same for positive and negative but the DIR pin changes (this is called sign-magnitude PWM)




When the I read the flashed firmware on the 7i96 these are the pins it says. I had mine wired up to the +pwm and -PWM.

Reading voltage across +PWM to pin 1 on TB2 (GND) does indeed start at 0 and go positive.

Should the direction be wired similar then as in Dir+ to GND. Or should this be pin 4 and 5 as in the screen shot?

Jools
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22 Nov 2019 13:20 #150914 by PCW
Replied by PCW on topic Mis placed thred
You need to be a little careful here.

How the exact wiring is done depends on what the PWM pin connects to
Normally you would only use one PWM or DIR pin and the common ground
unless you need differential signals, Note that in no case should you wire
the PWM/DIR or STEP/DIR pins to a common pin on the drive

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22 Nov 2019 13:25 #150915 by tommylight
Replied by tommylight on topic Mis placed thred
The title is very misleading.
This is the 6 thread with the same topic.

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22 Nov 2019 14:11 - 22 Nov 2019 15:41 #150924 by jools
Replied by jools on topic Mis placed thred
Agreed can the offending posts be moved? Or duplicated and deleted from here?

Did I somehow create a new thread with the same topic. If so please merge the last few posts with the PWM topic as it may be better.

Sorry
Last edit: 22 Nov 2019 15:41 by jools. Reason: change title

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