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MODELS 483C30, 483C50, 482M179 AND 483M217 GENERAL OPERATION MANUAL
2-7.1. Autoscaling
To avoid overload, these signal conditioners feature autoscaling for gain adjustment. It first sets maximum gain on all
channels, then decreases the gain setting of any channel on which an overload has occurred. The gain autoscale
continues until there is no overload with respect to the preset overload threshold level (standard ±10 volts) and sensed
signal of the channel. Final gain and overload status interrogation is possible through the command set. The correct
procedure for using the autoscale feature is as follows:
1.
Excite the structure under test.
2.
Enable autoscale (Autoscale on).
3.
Wait several seconds, until the unit is stabilized.
4.
Disable autoscale (Autoscale off).
5.
Read the gains of all channels.
6.
Begin test run.
2-7.2. Overload
The overload feature uses the same window comparator principle previously discussed. The +V
overload value of ±10 volts. When the input voltage (Vsignal of Figure 6) to the window comparator exceeds the
reference voltage limits, overload has occurred, and the comparator's output, which is normally "high," becomes "low."
This "low" state illuminates the overload LED and triggers the latch of overload detection circuitry. During regular
measuring time, the latch holds the occurrence of overloads until the user reads its status through the computer interface.
2-8.
Connector Configuration
All of these models have eight BNC jack output connectors, located on the rear panel, which are used regardless of the
input mode being used. The rear panel also includes eight BNC jack input connectors that are used for all input modes.
For the models 483C30, 482M179 and 483M217, there is an additional 10-32 jack connector, also located on the rear
panel, which are used for external calibration input signals.
The 482M179 and 483M217 units also have a 9-pin D-sub connector for output signals (Pins 1-8 correspond to channel
1-8 output signals)
Figure 6 Autoscale/Overload Window Comparator
7
is equal to the default
ref
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