7i77 +-10V outputs: unexpected voltage with analogena, no output with analogout

Hi all,I’m running into an issue with my 7i77 analog outputs and could really use some help figuring it out.Setup:

• 7i94 + 7i77 + 7i84
• LinuxCNC with Mesa HAL configuration
• QtDragon GUI

The issue:

• When I set hm2_7i94.0.7i77.0.1.analogena to True, I measure about 0.3V on all +-10V outputs, even without setting any value on an analogout<>.
• When I set a value on one of the analogout<> pins (e.g. analogout2 = 0.1) and leave analogena False, I measure no voltage on the corresponding output.
• What I expected:
  • No voltage at the +-10V outputs just by enabling analogena.
  • A voltage at the specific output only when both analogena is enabled and an analogout<> value is set.

My question:

Is this normal behaviour, or am I missing something in the configuration or wiring? What should I check next to diagnose this? 

 



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1- test with no wiring on analog outs
2- analog out and in on drives have polarity, check if correct.
3- 0.3V might be induced from other equipment while measuring, so try setting analog out to 5 or 10V, with drives disconnected or disabled

Hi Tommy,

Thanks for your answer. 

I have disconnected all drives and measured directly on the pins. (Indicated with the red dots on the image)

It doesn't matter what I set hm2_7i94.0.7i77.0.1.analogout0 to, the value stays 0V, or about 0.3V when hm2_7i94.0.7i77.0.1.analogena is enabled.

 

I think you are measuring the enable pins (1,2) rather than the analog outputs
(3,4)

Ah, yes. ping (3,4) indeed do show the correct voltage. But now I'm completely confused where the ground from the drive and the cable shielding should be connected. 

If I understand the manual correctly:

1. The twisted pair wiring shield should be connected to the 7i77 GNDN (pin 3), which is now used for the +-10V signal
2. The drives common or GND signal should be connected to the 7I77 power GND with a separate wire. Where is the power GND on the 7i77? 
   
   Perhaps I'm miisreading something but that's what I got out of it.
   
    

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The drives common or GND signal should be connected to the 7I77 power GND with a separate wire. Where is the power GND on the 7i77? 

This would be the drives analog common, or if the drive has differential inputs, Analog in -