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
µ
s 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
µ
s or more
5.20 Selecting the Time Base (Internal Clock or External Clock)