7i73 Analog in problem?

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2 years 9 months ago #291942 by greekart
7i73 Analog in problem? was created by greekart
Hello guys,
i have pots for feed/rapid/jog override, the ones for feed/rapid works but for jog not.
I have 7i96s with 7i73 connected, with pots connected to analog 0,1,2 inputs of 7i73
Code:
loadrt hm2_eth board_ip="10.10.10.10" config="num_encoders=1 num_pwmgens=1 num_stepgens=5 sserial_port_0=10xxxxxx" in my hal for jog override i use [code]loadrt hyst names=hyst.feedpot,hyst.rapidpot,hyst.jogpot loadrt scale names=scale.jog net  jogpot-raw          hm2_7i96s.0.7i73.0.0.analogin1 addf scale.jog servo-thread addf hyst.jogpot servo-thread setp hyst.jogpot.gain 0.05 setp hyst.jogpot.deadband 0.7 setp hyst.jogpot.step 0.01 setp hm2_7i96s.0.7i73.0.0.analogin1-scalemax 1.58 net  jogpot-raw         hyst.jogpot.in setp scale.jog.in       5000 setp scale.jog.offset   50 net jog-speed-gain      hyst.jogpot.out    scale.jog.gain net jog-speed           scale.jog.out My problem is that in hal_show when i change jog pot in analog 1 the analog 3 changes too and don't know if the code or the inputs are the problem, any thoughts? Thanks a lot Panos.
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2 years 9 months ago #291947 by PCW
Replied by PCW on topic 7i73 Analog in problem?
There is an issue with analog inputs 1 and 3 on the 7I73
there seems to be electrical leakage (about 50K ohms)
between inputs 1 and 3. Suggest using analog inputs
1 or 3 but not both until this is figured out. It may be fixable
in the 7I73 firmware but I am not sure currently.

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2 years 9 months ago #291948 by greekart
Replied by greekart on topic 7i73 Analog in problem?

There is an issue with analog inputs 1 and 3 on the 7I73
there seems to be electrical leakage (about 50K ohms)
between inputs 1 and 3. Suggest using analog inputs
1 or 3 but not both until this is figured out. It may be fixable
in the 7I73 firmware but I am not sure currently.
Ok, i will leave one unused. So i guess that not affect gui/machine and i will look from hal point why the jog-speed not work.

Thanks a lot

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2 years 1 month ago #310747 by spumco
Replied by spumco on topic 7i73 Analog in problem?

There is an issue with analog inputs 1 and 3 on the 7I73
there seems to be electrical leakage (about 50K ohms)
between inputs 1 and 3. Suggest using analog inputs
1 or 3 but not both until this is figured out. It may be fixable
in the 7I73 firmware but I am not sure currently.
 

@PCW,

Has this been fixed or any further investigation done?  I'm trying to connect three pots to my 7i73 and getting some strange results (cross-talk) in halshow.  I'll try some other pots in case one or more is dodgy, but I'd like to know if there's no way I can use all three.

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2 years 1 month ago #310750 by PCW
Replied by PCW on topic 7i73 Analog in problem?
Not, fixed yet but I may have some cycles soon
You should be able to use 0,1,2 but not 1 and 3
simultaneously unless driven by a low impedance source

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2 years 1 month ago #310752 by spumco
Replied by spumco on topic 7i73 Analog in problem?
I replaced all three pots with some 0-20k's and the problem is significantly better.

I'm using inputs 0, 1, and 2.

Behavior is a ~0.02v +/- jump on two of the inputs whenever I turn the third up or down to the limit.

All combinations behave the same way, and it looks more like voltage drop (or spike) as all three are connected to ACC pin 12 and GND pin 00.

I think I can live with this as-is since they're just overrides, but it'll be interesting to see if I get a spindle speed bump if I turn the FRO all the way down.  If so maybe I can add a filter in hal or something.

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2 years 1 month ago #311095 by spumco
Replied by spumco on topic 7i73 Analog in problem?
Minor follow-up for anyone interested.

In the earlier posts, all three pots shared a single power & gnd pin off the 7i73.  Result was a small voltage spike (up& down) on two of the analog inputs whenever I twiddled the third pot to max or min.  Same for all three pot combinations.

As an experiment I split one of the pots off and powered it from the other 7i73 analog reference pin, and used a separate GND pin.  So two pots were connected to pin11 & pin1 (AVDD #1), and the third connected to pin12 & pin2 (AVDD #2).

Result was a massive drop in the input spike amplitude on whichever two inputs weren't being adjusted.

Takeaway... if you're using multiple pots, use multiple AVDD pins to power them if possible.

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