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Jog speed using potentiometer
So far I have a 10K pot that reads from 16.79VDC to 24VDC for the analog input on the 7i84 which I will need to scale later on to fit the range I need.
net jog-speed <= hm2_5i25.0.7i84.0.2.analogin0
I can see the jog-speed vary in the Hal but no change in the jog-speed slider no the overall jog speed while moving a axis.
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- tommylight
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You mention that the voltage changes from 17.xx to 24 on the input of mesa card, right?
Well that means you have only 2 wires from the potentiometer connected, or you have all 3 wires connected but at wrong places.
So, you have to connect the centre wire from the potentiometer to the input of the mesa card, the other 2 wires on the left and right on the potentiometer go: one to gnd and the other to +24V. That is if the analogue input on the mesa card is for 24V.
After you test and it works, only after it works see if it is correctly wired to up the speed as you turn it right. If not, just switch places of +24V and GND on the potentiometer. Do not under any circumstances wire the middle potentiometer pin to anything else except the analogue input on the card.
Just in case you find out that the potentiometer does not adjust speed linearly, check to see if it is a linear or logarithmic version, you need it to be linear. If it is linear and it still does not adjust properly, change the potentiometer, as that is a sure sign that it is fried due to miss wiring.
Phew, that should be all the possibilities of wiring a potentiometer .
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Duc wrote: I can see the jog-speed vary in the Hal but no change in the jog-speed slider no the overall jog speed while moving a axis.
I am not particularly clear what you are trying to do, looking at the HAL.
You have a lot of mux components for setting the MPG jog rates. I assume that is working?
But, you also seem to be trying to use the analog input to set the keyboard(?) jog speed.
Which LinuxCNC GUI are you using? I don't know if any of them allow you to set the jog slider from an external input (because the on-screen slider has no way to do the reverse, move the physical knob)
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andypugh wrote:
Duc wrote: I can see the jog-speed vary in the Hal but no change in the jog-speed slider no the overall jog speed while moving a axis.
I am not particularly clear what you are trying to do, looking at the HAL.
You have a lot of mux components for setting the MPG jog rates. I assume that is working?
But, you also seem to be trying to use the analog input to set the keyboard(?) jog speed.
Which LinuxCNC GUI are you using? I don't know if any of them allow you to set the jog slider from an external input (because the on-screen slider has no way to do the reverse, move the physical knob)
Using AXIS
All the mux are working fine MPG jog rates, spindle rpm and feed override. I see the slider change in AXIS gui when I adjust the knobs for those items. I do not see anything change for the jog-speed when I adjust the knob, only the I/O value for jog-speed and the analogin.0
I would like to use the knob to adjust the jog speed for when I use the keyboard to move the table around. The end game for the setup is a switch to turn a jog on like what is used on a manual mill equipped with a power drive unit.
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tommylight wrote: Not my forte but,
You mention that the voltage changes from 17.xx to 24 on the input of mesa card, right?
Well that means you have only 2 wires from the potentiometer connected, or you have all 3 wires connected but at wrong places.
So, you have to connect the centre wire from the potentiometer to the input of the mesa card, the other 2 wires on the left and right on the potentiometer go: one to gnd and the other to +24V. That is if the analogue input on the mesa card is for 24V.
After you test and it works, only after it works see if it is correctly wired to up the speed as you turn it right. If not, just switch places of +24V and GND on the potentiometer. Do not under any circumstances wire the middle potentiometer pin to anything else except the analogue input on the card.
Just in case you find out that the potentiometer does not adjust speed linearly, check to see if it is a linear or logarithmic version, you need it to be linear. If it is linear and it still does not adjust properly, change the potentiometer, as that is a sure sign that it is fried due to miss wiring.
Phew, that should be all the possibilities of wiring a potentiometer .
Not sure why I forgot the 3rd leg but I will fix that once I have the I/O working.
Thanks
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Duc wrote: Using AXIS
All the mux are working fine MPG jog rates, spindle rpm and feed override. I see the slider change in AXIS gui when I adjust the knobs for those items. I do not see anything change for the jog-speed when I adjust the knob.
There is a difference between an MPG and a potentiometer. A potentiometer is an absolute device and an MPG is a relative device.
This means that an MPG and a GUI slider can work together to alter a setting, this isn't possible with a potentiometer.
Would it be possible to use a small encoder in place of the potentiometer? There are some low-count ones available in the same form-factor as the pot. ( ).
You can count those perfectly OK with a software encoder counter in HAL (running in the servo thread, you won't make 1000 clicks per second) if you have run out of MPG inputs on your cards.
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Antonio B. wrote: so isn't possible to use a potentiometer on MPG?
Everything is possible, but some things are difficult.
A potentiometer only turns through a limited range, how do you propose to deal with that?
Or do you want the pot to control jog speed? (and is so, how do you actually stop?)
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I'm trying to use it infact but I 'm in the same situation: I see in halmeter the correct value but the velocity not increasing....
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The problem is that I cannot found a way to configure the halui.jog-speed dynamically using the max velocity value from halui.max-velocity.value.
I saw that halui.jog-speed is increasing following halui.max-velocity.value after I have se it as the following:
net jog-speed <= halui.max-velocity.value
net jog-speed halui.jog-speed
but I cannot see any increasing on the real speed machine.
Any idea?
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