My AT-MIO-16E-2

[Sam]

My AT-MIO-16E-2 is acting up lately. I am reading input of ~-6V in all
channels even when the cable to BNC 2090 is disconnected. The V
starts out from 60 and slowly drifts up to -6 V. I ran the diagnostic
online where the device failed the. Could this be the root cause of my
errorneous voltage reading? Is there a solution to this problem?


Digital Lines -- Read/Write Verification
-------------------------------------------------------------------------------------------------------------------------------
This test verifies the operation of the digital I/O circuitry by
performing line input and output. A Boolean value is written to each
digital line and then read back internally. Both True and False values
are tested. To pass, each value read must matc
h the value written.

Testing Port 0, Line 0: PASS
Testing Port 0, Line 1: Please Wait. . .

FAILURE: Incorrect digital value read internally from Port 0, Line 1,
Expected False, Read True.

Testing Port 0, Line 1: FAIL
Testing Port 0, Line 2: FAIL
Testing Port 0, Line 3: FAIL
Testing Port 0, Line 4: FAIL
Testing Port 0, Line 5: FAIL
Testing Port 0, Line 6: FAIL
Testing Port 0, Line 7: FAIL

FAIL: Device 1 has failed the Read/Write Verification Test


Digital Ports -- Read/Write Verification
-------------------------------------------------------------------------------------------------------------------------------
This test verifies the operation of the digital I/O circuitry by
performing port input and output. A binary pattern is written to each
digital port and then read back internally. All possible binary
patterns are tested. To pass, each pattern read must match the pattern
written.

Testing Port 0: Please Wait. . .

FAILURE: Incorrect digital value read internally from P
ort 0, Expected
0, Read 2.

FAILURE: Incorrect digital value read internally from Port 0, Expected
1, Read 3.

FAILURE: Incorrect digital value read internally from Port 0, Expected
4, Read 6.

[JoshuaP]

I am not sure why your digital lines are failing, but they should not affect your analog input lines. You need to make sure that the cable is disconnected from the AT-MIO-16E-2 when you run the test. Also, have you run the Resource Test in MAX, because it can help diagnosis resource problems.

Now for the floating lines. This is actually very common. When nothing is connected to the pins the voltage will charge up on the leads. Sense the pins are not connected to anything and the voltage has no were to go the lines will normally completely saturate the capacitors on the board.

This is not a bad thing and it should not affect your measurements, if you do not scan the channels that are not connected. If you are worried about the unused floating signals, you
can wire the unused inputs to ground.

If you are performing measurements and notice that the inputs are floating you should check your grounding methods. In general use RSE for floating sources, NRSE and DIFF for grounded signal sources. If you want to use NRSE or DIFF on a floating signal you will need to add a 10-100kOhm bias resistor from the negative lead to AIGND to reference the signal. Refer to this KB for more help.

http://digital.ni.com/public.nsf/websearch/DF70FCE03D397BFE86256A3700780FFA?OpenDocument

I hope this helps,

Joshua