Digital I/O, Analog Outputs, and External Feedback 11-7
Analog outputs
Model 6514 has two analog outputs on the rear panel. The 2V ANALOG OUTPUT provides
a scaled ±2V output with a value of ±2V corresponding to full-range input. The PREAMP OUT
is especially useful in situations requiring buffering. These two analog outputs are discussed in
the following paragraphs.
WARNING When floating input low above 30V RMS from earth ground, hazardous
voltage will be present at the analog outputs. Hazardous voltage may also
be present when the input voltage exceeds 30V RMS in the volts function,
or when input currents exceed 30pA in the amps function.
CAUTION Connecting PREAMP OUT, COMMON, or 2V ANALOG OUTPUT to
earth while floating the input may damage the instrument.
2V analog output
The 2V analog output provides a scaled ±2V output that is non-inverting in the volts mode.
Connections for using this output are shown in Figure 11-5. For a full-range input (i.e. 2V on
the 2V range), the output will be 2V. Example analog outputs are listed in Table 11-2.
The 2V analog output signal is not corrected during calibration. Gain errors of up to 15% may
appear at this output, depending on function and range.
The output impedance is 10kΩ. To minimize the effects of loading, the input impedance of
the device connected to the 2V analog output should be as high as possible. For example, for a
device that has an input impedance of 10MΩ, the error due to loading will be approximately
0.1%.
NOTE Rel and the result of mX+b or percent have no affect on the analog output. The 2V
analog output is scaled only to the actual input.
Table 11-2
Example 2V analog output values
Range Applied signal
Analog output
value (nominal)*
20pA 10.5pA -1.05V
2uA -1.65µA 1.65V
200mV 140mV 1.4V
200V -36V -0.36V
200kΩ 175kΩ 1.75V
20nC 19nC -1.9V
* Output values are within ±15% of nominal value.
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