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IEEE-488 Programming
3.2.9 Baseline suppression (N)
Purpose
Format
Default
Description
Programming
Notes
Examples
3-12
To enable or disable baseline suppression.
N0
Disable suppression
N1
Enable suppression
Upon power-up, or after receiving a DCL or SDC command, suppression will be disabled (N0).
The baseline suppression mode allows a stored offset value to be subtracted from subsequent
readings. When the suppression mode is enabled with the appropriate command, the instrument
will internally store the baseline value with the next triggered conversion. All subsequent read-
ings will be the difference between the stored baseline value and the actual signal level. For ex-
ample, if 100mV is stored as a baseline, that value will be subtracted from the following
readings. See paragraph 2.10.2 for a complete description.
To use baseline suppression, perform the following steps:
1.
Cancel baseline suppression by sending N0X if already enabled.
2.
Select a range and function consistent with the expected measurement.
3.
Connect the signal to be used as a baseline to the instrument input.
The voltage present on the input terminals may be larger than
the displayed value. For example, if a 150VDC baseline is stored,
an applied voltage of +175V will result in a displayed reading of
only +25V.
4.
Enable baseline suppression by sending N1X over the bus. The baseline will be stored when
the command is executed.
5.
Disconnect the baseline signal from the instrument, and connect the signal to be measured
in its place. Subsequent readings will be the difference between the baseline and the applied
signal.
1.
Baseline suppression reduces the dynamic range of the measurement. For example, if the
stored baseline value is 100mV on the 200mV range, an input voltage of 100mV or more
would over-range the instrument even though voltages up to 199.99mV are normally within
the capabilities of the 200mV range. If the instrument is in the auto-range mode, it will
move up range if necessary.
2.
Setting the range lower than the stored baseline value will over-range the instrument.
3.
Accurate control over when the baseline is actually stored may be achieved by placing the
instrument in a one-shot trigger mode. Once the desired baseline value is connected to the
instrument, the baseline can be stored by sending N1X.
4.
Function changes cancel baseline suppress. Refer to paragraph 2.10.2 for details concerning
suppress.
N1X
Enable suppress.
N0X
Disable suppress.
WARNING
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