ETAS
Digital Input Channels ("DI" Connection)
ES930.1
-
User Guide
42
5.2.6
Calculation of Cycle Duration, Frequency and Scan Ratio
In the time measurement operating mode, the ES930.1 acquires the active and
inactive time of a period or a cycle of the signal at the measuring channel. The
measured times are the basis for calculating the cycle duration, frequency and
scan ratio.
Measuring Procedure
In the application software, parameters and measuring procedures can be
selected for the time measurement for every measuring channel:
• Measurement of the duration of the last period
• Measurement of the duration of the last cycle
Calculation of the Cycle Duration
The cycle duration T is the sum from active time and inactive time:
T = active time + inactive time
Calculation of the Frequency
The frequency is the reciprocal value of the cycle duration T of the digital signal:
The frequency is determined from the measured values of the active and inac
-
tive time as reciprocal value of the sum of the active and inactive time during a
period or during a cycle or from the reciprocal value of the scan ratio.
Calculation of the Scan Ratio
The scan ratio indicates the ratio of the length of the active state (pulse dura
-
tion) to the cycle duration of the digital signal in percent:
The scan ratio is determined from the measured values of the active and inac
-
tive time as quotient of the active time and the sum of the active and inactive
time during a period or during a cycle.
NOTE
The calculation of the cycle duration, frequency and scan ratio is done appli
-
cation-specific in INCA or in the RP model from the values for the active and
inactive time determined by the ES930.1.
f
1
T
---
1
active time inactive time
+
----------------------------------------------------------------
=
=
Scan ratio
active time
active time inactive time
+
---------------------------------------------------------------- [%]
=
