3-56 Section 3: Model 9100 Controls: Working with Front Panel Controls — Tutorials
Final Width = 215mm
3.4.7.2 Smooth Increments — No Range Switching
The 9100 provides a continuous dynamic range for its functions. As far as possible, this
is made available by smooth increments, and no range switching is implemented.
However, two main characteristics of such a wide dynamic range impose themselves
upon the practical achievement of this aim. To illustrate their implications, we have
chosen DC Voltage as an example.
3.4.7.3 DC Voltage Example
The DC Voltage output is variable in steps from 1µV up to 1,050V.
Scale Length
It is extremely unlikely that users will ever wish to adjust voltages in the order of 1000V
at the maximum possible resolution of 1µV (this would require a scale length of
1000.000000!).
For efficient operation at the levels of DC Voltage accuracy required of the 9100, a scale
length of six significant digits is more than adequate, so this has been implemented. Five
spans of DC Voltage exist within the full DC Voltage dynamic range, each with its own
constant absolute resolution. In the following table, the extent of each span is related to
its resolution:
Absolute Span of Values Nominal
Resolution Span Value
1µV -320.000 mV to +320.000 mV 300mV
10µV -3.20000 V to +3.20000 V 3V
100µV -32.0000 V to +32.0000 V 30V
1mV -320.000 V to +320.000 V 300V
10mV -1050.00 V to +1050.00 V 1000V
The span thresholds have been fixed at the above values, as explained earlier, to avoid
the need to cross thresholds during normal slewing operations around calibration points.
Internal Hardware Configurations
Over such a wide range of values, several different analog hardware configurations are
necessary. This only makes an operating difference when output is on, as it must be turned
off in order to reconfigure, then back on again for the new value. As far as is possible,
the configuration boundaries are arranged to occur at the resolution thresholds, and the
interruption is very brief.
Rules of passage across thresholds are incorporated into the internal firmware to
minimize interruptions to smooth operation.
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