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Analog input 1746-NI4

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#1 Guest_Guest_James_*

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Posted 03 December 2004 - 11:07 AM

Hi all,
I used AB 1746-NI4 analog module to read the 4-20ma from Zener AC Drive. I have correct measured signal (regulated from 4 to 20ma) but why the reads data on SLC always 32767? event signal is 4 mA? How to solve this problem?
Thank you.
James

#2 panic mode

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Posted 03 December 2004 - 12:49 PM

the value you are getting is raw value. you need to scale it to engineering units (check out SCP instruction). if the reading is always like that (it doesn't change), something is not right, the input is always on 20mA
(0-20mA range translates to 0-32767 counts, when using only 4-20mA range, reading is something like 6553-32767).

#3 Snerkel

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Posted 03 December 2004 - 12:55 PM

The NI4 comes set to voltage input as default, I bet the dip switches on the card are still set to volts instead of current.

On the side of the card the label shows the dip switch settings you need.

#4 Snerkel

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Posted 03 December 2004 - 01:06 PM

In fact the value 32767 shows us it must be set to volts as the full range value for 20mA is 16384

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Posted 03 December 2004 - 03:21 PM

doh :shrug:

#6 Ken Moore

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Posted 03 December 2004 - 04:02 PM

I know the dip switch is the problem, but just in case.
Scaling example, the following scales an input from a NI4 for 0-100%,

Attached Images

  • SCALE.jpg

Edited by Ken Moore, 03 December 2004 - 04:04 PM.









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