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6.3 Output function (switching output and analogue output)
The two outputs of the VNB211 are used for the alarm (pre-alarm, main alarm)�
The first output (OU1) can be used as digital or analogue output� The switching
logic (which characteristic values are alarmed in which way) can be set only in the
PC software�
System errors (e�g� a failed self-test) are also signalled on the first output (OU1)�
If the output is used as digital output, the output pulses with a frequency of 1 Hz
in case of a fault� A current of 22 mA is provided as analogue output in case of a
system error�
6.4 Self-test
The self-test checks the function of the VNB's measuring cell� The self-test
is made during power-on and can in addition be started manually via the PC
software or the buttons on the unit�
Displays on the unit:
• Self-test passed → [PASS]
• Self-test failed → [FAIL]
> LED OU1 flashes
Output OU1
- pulsing if "digital" output function (NC, NO)
- supplies 22 mA if "analogue" output function
6.5 Averaging of a vibration characteristic value
6.5.1 Calculation
Formula to determine the new diagnostic value:
("previous diagnostic value" x (1 - averaging)) + ("new measurement" x averaging)
= new diagnostic value
Example
Averaging 0�25; "previous diagnostic value" 17�3 mm/s;
"new measurement" 14�7 mm/s
(17�3 mm/s x (1 - 0�25)) + (14�7 mm/s x 0�25) = 16�65 mm/s
For the VNB211 the measurement time between "previous diagnostic value" and
"new measurement” can be configured via the PC software�
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