GRAPHTEC gl820 User Manual page 63

(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.
Input signal
Shortest interval
External Sampling pulse
Memory capture data
• 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 filter 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.
The shortest interval is as shown in the following table:
Number of Measuring
Channels *1
1 CH
2 CH
3 to 5 CH
6 to 10 CH
11 to 20 CH
21 to 50 CH
51 to 100 CH
101 to 200 CH
*1 The Number of Measuring Channels is the number of channels for which the input setting is not OFF.
Sampling
interval
Data for this
Shortest interval
Digital filter OFF
10ms
20ms
50ms
100ms
200ms
500ms
1 s
2 s
CHAPTER 3 Settings and Measurement
Data for this
Shortest interval
Digital filter ON
200ms
500ms
1s
1s
2s
5s
10 s
20 s
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