IM 701240-01E
5-50
Explanation
Time Base
Select from the following:
Int
Internal clock signal (the specified record time and sample rate are valid)
Ext
Clock signal applied to the external clock input terminal (the specified record time and sample
rate are valid)
If Ext Is Selected
Apply a clock signal of the following specifications to the TRIG OUT/EXT CLK IN
terminal (shared with the trigger output terminal) on the left side panel.
TRIG OUT/
EXT CLK IN
Item Specifications
Connector type RCA jack
Frequency range See Note below
Input level TTL (0 to 5 V)
Valid edge Rising
Minimum pulse width 400 ns or more for high and low
External clock frequency range 1 MHz maximum
Rise/Fall time of the clock 2 µs or less
Note
• The upper limit frequency of the external clock is as follows:
Input Module Upper Limit Frequency
701250/701251/701255 1 MHz
701267/701270/701271/701275 100 kHz
701280 25 kHz
701261/701262 100 kHz when measuring voltage,
500 Hz when measuring temperature
701265 500 Hz
• If the external clock frequency exceeds the upper limit frequency of the module, sampling is
executed at the upper limit frequency.
Circuit Diagram and Timing Chart of the External Clock Input
LCX14 or equivalent
EXT TRIG OUT
EXT CLK IN
100 Ω
+5 V
HC245 or equivalent
4.7 kW
100 pF
Sample edge
(Rising)
400 ns or
more
400 ns or
more
1 µs or more
5.20 Selecting the Time Base (Internal Clock or External Clock)
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