Creating a tachometer signal with Mesa 7i77?
21 Dec 2015 14:54 #67204
by jeeybee
Creating a tachometer signal with Mesa 7i77? was created by jeeybee
I´m converting an old metal mill with analog fanuc servos and apparently it does not have tachometers on the motors but the velocity units need a tachometer signal which is currently created by the fanuc system from the encoder signal.
So what I have figured out so far is that I need to use the encoder velocity feedback, convert it from PPM to RPM and then scale it and send it to an analog output.
I think I even found an example of this a few month ago and have been trying to find it all day with no luck.
So if anyone happends to know were to find an example it would be great, otherwise my first question is:
Do I use a scale in the servo thread or can I somehow do this right in the hardware?
So what I have figured out so far is that I need to use the encoder velocity feedback, convert it from PPM to RPM and then scale it and send it to an analog output.
I think I even found an example of this a few month ago and have been trying to find it all day with no luck.
So if anyone happends to know were to find an example it would be great, otherwise my first question is:
Do I use a scale in the servo thread or can I somehow do this right in the hardware?
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21 Dec 2015 15:22 #67205
by PCW
Replied by PCW on topic Creating a tachometer signal with Mesa 7i77?
Depending on how you created your original HAL file, its likely you already have a nets for encoder velocity
(PNCCONF makes them for example, and I think the example hostmot2-servo HAL files have these nets as well)
so basically all that is needed is to connect these nets to some spare 7I77 analog outputs
There is no additional scaling needed, as the analog outputs are scalable
If you post your existing HAL file, I can show the required net commands
(PNCCONF makes them for example, and I think the example hostmot2-servo HAL files have these nets as well)
so basically all that is needed is to connect these nets to some spare 7I77 analog outputs
There is no additional scaling needed, as the analog outputs are scalable
If you post your existing HAL file, I can show the required net commands
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21 Dec 2015 17:22 #67213
by jeeybee
Replied by jeeybee on topic Creating a tachometer signal with Mesa 7i77?
Hello PCW, dependable as always ![:) :)](/media/kunena/emoticons/smile.png)
Here is part of the hal file and what I have tried to accomplish so far
# encoder feedback
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.counter-mode 0
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.filter 1
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.index-invert 0
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.index-mask 0
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.index-mask-invert 0
#Tachometer generator
setp hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout3-scalemax [AXIS_0]OUTPUT_SCALE_TACHO
net encoder.0.velocity <= hm2_[HOSTMOT2](BOARD).0.encoder.00.velocity
net encoder.0.velocity => hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout3
![:) :)](/media/kunena/emoticons/smile.png)
Here is part of the hal file and what I have tried to accomplish so far
# encoder feedback
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.counter-mode 0
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.filter 1
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.index-invert 0
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.index-mask 0
setp hm2_[HOSTMOT2](BOARD).0.encoder.00.index-mask-invert 0
#Tachometer generator
setp hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout3-scalemax [AXIS_0]OUTPUT_SCALE_TACHO
net encoder.0.velocity <= hm2_[HOSTMOT2](BOARD).0.encoder.00.velocity
net encoder.0.velocity => hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout3
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21 Dec 2015 17:25 #67214
by jeeybee
Replied by jeeybee on topic Creating a tachometer signal with Mesa 7i77?
Something is not right with the scale though, nothing happens when I change it.
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21 Dec 2015 17:35 #67216
by PCW
Replied by PCW on topic Creating a tachometer signal with Mesa 7i77?
if you change the analog out scalemax parameter
you will also likely have to change the minlimit and maxlimit
parameters for the analog out
you will also likely have to change the minlimit and maxlimit
parameters for the analog out
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21 Dec 2015 17:54 #67217
by jmelson
Jon
Replied by jmelson on topic Creating a tachometer signal with Mesa 7i77?
TxRx Labs in Houston has a Burgmeister powerhawk mill that they did this on, and it is working. You could check with them to get the config file set.So what I have figured out so far is that I need to use the encoder velocity feedback, convert it from PPM to RPM and then scale it and send it to an analog output.
Jon
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21 Dec 2015 18:17 #67218
by jeeybee
Replied by jeeybee on topic Creating a tachometer signal with Mesa 7i77?
jmelson: Thanks, that can be a backup plan
Now it seem like it does it right, I can change the value and get different voltages when I turn the MPG I hooked up to test this.
All for now, thank you very much PCW.
Now it seem like it does it right, I can change the value and get different voltages when I turn the MPG I hooked up to test this.
All for now, thank you very much PCW.
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