Reading Analog Input Mesa 6i25 ( Potentiometer/NTC/PTC)

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15 Jan 2023 18:16 #262053 by hitchhiker
Hi!


Can someone help me please to get a small project working?

Project:

I want to display analog values in linuxcnc. 
I use a 6i25 and want to use 1 pin as Analog Input.  is this possible?
on this Analog Input i connect a NTC or Potentiometer.

thanks

 

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15 Jan 2023 19:50 #262056 by tommylight
No.
Use an arduino to read the value and send to Mesa 6i25 as PWM or BCD code or even better as encoder velocity.

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15 Jan 2023 19:52 #262057 by tommylight
Sorry,
There are also some small DIP8 packaged chips that do voltage to frequency for 0-10V input, and output 0-10kHz roughly.
Very cheap and litle discrete components required.

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15 Jan 2023 22:47 #262076 by hitchhiker
mmh ok... have you a example?

how to read freq or pwm on the 6i25?!


thanks

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16 Jan 2023 01:09 #262080 by tommylight
Frequency is easy as all Mesa FPGA boards do encoder counting.
PWM, i never used so no idea how to go about it.
Plenty of us here use Mesa THCAD that reads the arc voltage from a plasma source and turns that into frequency that is read and displayed on screen again as voltage. We need this due to isolation from high voltage and interference.
Here are some of CNC plasma machines i have built:
forum.linuxcnc.org/show-your-stuff/38547...plasma-build?start=0

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16 Jan 2023 01:13 #262081 by tommylight
LM331 is very cheap voltage to frequency converter:
www.ti.com/lit/ds/snosbi2c/snosbi2c.pdf

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16 Jan 2023 23:24 #262191 by andypugh
What are you measuring? It is possible to bit-bang serial from some ICs including a thermocouple amplifier:
linuxcnc.org/docs/stable/html/man/man9/max31855.9.html
Though that needs 3 pins for the SPI interface.

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