Duty cycle evaluation
The duty cycle describes the ratio of pulse duration tON to period value T.
Duty cycle [0.01%] = Pulse duration tON/Period value T * 100
The following process data are available:
Index (hex) | Name | Meaning | Default |
|---|---|---|---|
60n0:23 | Duty cycle | Ratio of pulse duration tON to period value T. Output in 1/100 | 0x0000 (0dec) |
60n0:24 | Duty cycle min | Smallest measured duty cycle value during the current measurement | 0x2710 (10000dec) |
60n0:25 | Duty cycle max | Largest measured duty cycle value during the current measurement | 0x0000 (0dec) |
The duty cycle is measured as follows:
- The pulse duration tON is measured. This is the time between the rising and falling edge of input A.
- The period value T is measured. This is the time between two positive edges of input A.
- The times are measured with a resolution of 10 ns.
- In each case the last period within the PLC cycle is considered and output as separate process data in index 0x60n0:23 "Duty cycle".
- The output is 1/100 of the measured value.
- The duty cycle measurement delivers valid results in RS422 mode up to 1 MHz with an accuracy of typically 1% - 2%. Larger measuring errors may occur at input frequencies above 1 MHz.
Fig.167: Duty cycle measurementThe smallest and largest measured duty cycle value can be reset via the command object in index 0xFB00:01 "Request".
0xFB00:01 "Request" | Description |
|---|---|
0x9130 | Index 0x6000:24 "Duty cycle min" for channel 1 is set to zero |
0x9140 | Index 0x6000:25 "Duty cycle max" for channel 1 is set to zero |
0x9131 | Index 0x6010:24 "Duty cycle min" for channel 2 is set to zero |
0x9141 | Index 0x6010:25 "Duty cycle max" for channel 2 is set to zero |