GRAPHTEC GL820 - Page 63

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CHAPTER 3 Settings and Measurement
(2)-4 External sampling
Enables or disables external sampling.
When the external sampling function is enabled, data is captured at the shortest intervals and retained
temporarily.
This retained data is updated at the shortest intervals.
When an external sampling pulse is received, the retained data is written to the memory.
(See the following figure.)
Therefore, the maximum error in time between the actually captured data and the external sampling pulse
is the same as the shortest interval.
* Refer to the next section, "(2)-5 AC line filter" for details on the shortest interval.
Sampling
interval
Data for this Data for this
Memory capture data
Shortest interval
Input signal
External Sampling pulse
 • IftheexternalsamplingfunctionisON,theexternalinputcannotbeselectedforthetriggersetting.
If the external input has already been set, the trigger will be set to Off.
• Whenyoumeasuresignalswithhighnoiselevels,settheAClinelterdescribedinthenextsectionto
ON.
(2)-5 AC line filter
Enables or disables the AC line filter while external sampling is enabled.
Enable this setting to enable the digital filter. - When you use external sampling and measure signals with
high noise levels, set the AC line filter to ON.
The shortest interval is displayed under the settings.
Shortest interval
The shortest interval is as shown in the following table:
Number of Measuring
Channels *1
Shortest interval
Digital filter OFF Digital filter ON
1 CH 10ms 200ms
2 CH 20ms 500ms
3 to 5 CH 50ms 1s
6 to 10 CH 100ms 1s
11 to 20 CH 200ms 2s
21 to 50 CH 500ms 5s
51 to 100 CH 1 s 10 s
101 to 200 CH 2 s 20 s
*1 The Number of Measuring Channels is the number of channels for which the input setting is not OFF.