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5-8
IM 701210-05E
Explanation
Selecting the Input Coupling
Select how the input signal is coupled to the vertical control circuit from the following:
AC:
Acquires only the AC component of the input signal.
DC:
Acquires and displays all the components (DC and AC) of the input signal.
Selectable only when observing voltage.
GND:
Checks the ground level.
TC:
Select this type when observing temperature.
AC-RMS: Converts and displays only the AC component of the input signal.
DC-RMS: Converts and displays both DC and AC components of the input signal.
ACCL:
Select this type when measuring acceleration.
Input Coupling and Frequency Characteristics
The frequency characteristics when AC and DC are selected are shown below.
Note that low-frequency signals and signal components are not acquired if AC is
selected as indicated in the figure below.
0 dB
–3 dB
–3 dB point
1
Attenuation
0 dB
–3 dB
–3 dB point
1
Attenuation
The lower frequency –3 dB point when using AC coupling*
Input frequency
Input frequency
When “AC” is selected
When “DC” is selected
1. The value varies for each input module. For details, see chapter 19.12, “Module Specifications.”
Notes for the 701261, 701262, 701265, 701275, and 701280
• If the input coupling is changed from TC to DC or DC to TC while the waveform
acquisition is stopped on the 701261 (UNIVERSAL), 701262 (UNIVERSAL (AAF)), or
701265 (TEMP/HPV), the waveforms are no longer drawn. If you set the input
coupling to the original setting, the waveforms are redrawn.
• If the input coupling is changed from ACCL to some other setting or some other
setting to ACCL while the waveform acquisition is stopped on the 701275 (ACCL/
VOLT), the waveforms are no longer drawn. If you set the input coupling to the
original setting, the waveforms are redrawn.
• If you change the contents of the function of the FV setting while the waveform
acquisition is stopped on the 701280 (FREQ), the waveforms are no longer drawn. If
you set the contents of the function to the setting that was present during
measurement, the waveforms are redrawn.
CAUTION
• If the input coupling is AC and the frequency of the input signal is less than 1
Hz, the DL750/DL750P does not attenuate the signal at the input terminal to 1/
10, even if a probe with 10:1 attenuation and input resistance of 10 M
Ω
is used.
Make sure not to input a voltage that has a signal component less than 1 Hz that
exceeds the maximum input voltage of each module.
• Do not apply a voltage exceeding the maximum input voltage or maximum
allowable common mode voltage of the input modules. This may cause damage
to the input section.
5.8 Setting the Input Coupling