Velocity, speed calculation
In addition to the counter value, the terminal offers the option of measuring the velocity and speed. The measured values are determined through parameterization of the frequency values. The following limit values apply:
Measured value output | Measured value limit | Comment | |
|---|---|---|---|
lower | top | ||
Frequency value | 0.095 Hz | 1 MHz | with 4-fold evaluation |
0.095 Hz | 100 kHz | with 4-fold evaluation | |
The frequency measurement is carried out as described in chapter "Frequency measurement (Frequency value)". In addition, the frequency value can be converted using the two indices 0x80n0:1D "Frequency numerator" and 0x80n0:1E "Frequency denominator".
Index (hex) | Name | Meaning | Default |
|---|---|---|---|
80n0:1D | Frequency numerator | Frequency numerator | 0x0000001 (1dec) |
80n0:1E | Frequency denominator | Frequency denominator, | 0x0000001 (1dec) |
Thus, the frequency can be normalized for application-specific speed measurement. The measured value continues to be output in the process data via "Frequency value" (index 0x60n0:13).
The calculated measured value has the following relationship to the frequency:
Example for velocity calculation in m/s
- 200 mm travel corresponds to one full mechanical revolution of an encoder.
- The encoder has a 12-bit resolution, i.e. 4096 lines, which corresponds to 4096 periods on track A.
The velocity value is determined as follows:
Index (hex) | Name | Example: velocity in m/s | Comment |
|---|---|---|---|
Frequency numerator | 0x00000C8 (200 dec) | Travel path, conversion to m via "Frequency denominator" | |
Frequency denominator | 0x003E8000 (4096000 dec) | Specification of the number of periods over the travel path and conversion of the travel path to m |
Example Calculation of speed frot in revolutions/s
- After one full rotation, 4-fold evaluation (0x80n0:06 "Evaluation mode") results in a numerator value of 16384 increments. This corresponds to 4096 periods on track A.
- "Frequency numerator" can be used to convert the time unit into minutes. Note the scaling of the frequency value (0x80n0:13 "Frequency scaling"):
Conversion to minutes depending on "Frequency scaling" | |||
|---|---|---|---|
Index (hex) | Entry | Index (hex) | Entry |
0x80n0:13 Frequency scaling | 100dec: 0.01 Hz | 0x80n0:1D Frequency numerator | 0x00001770 (6000dec) |
1dec: 1 Hz | 0x0000003C (60dec) | ||
Index (hex) | Example: Speed | Comment |
|---|---|---|
80n0:1D Frequency numerator | 0x0001770 (6000 dec) | Output of the value in 0.01 rpm |
80n0:1E Frequency denominator | 0x0001000 (4096 dec) | Conversion factor in periods / m |