Scaling-Register (R35) IP5209
The scaling register sets the scaling or interpolation of the module. It should be adjusted to the used measuring hardware.
By scaling, the counter value can optimally be adapted to the application. Therefore a calculating in the user program is not needed.
The value in R35 sets the number of bits that are represented in the quarter period (Default: 0x0008).
The following graph shows the sinusoidal signal.
With the default setting R35 = 0x0008 the counter value D3/D2/D1/D0 of the sine/cosine input device is represented in the following way:
|
Bit |
31 ... 10 |
9 |
8 |
7 |
6 |
6 |
4 |
3 |
2 |
1 |
0 |
|
Name |
Number of signal periods |
zero crossings |
resolution within the quarter period | ||||||||
|
Comment |
4.194.304 periods |
1024 steps within one period | |||||||||
e.g. the counter value with a R35 = 0x0004:
|
Bit |
31 ... 6 |
5 |
4 |
3 |
2 |
1 |
0 |
|
Name |
Number of signal periods |
zero crossings |
resolution within the quarter period | ||||
|
Comment |
67,108,864 periods |
64 steps within one period | |||||
Calculation sample
Sine/Cosine-measuring device 2 µm signal period,
Default setting R35: 0x0008
Counter value set to zero in the released status of the input device (Control-Byte = 0x0004),
Input device pushed over the whole measuring scale.
Result:
|
Byte |
D3 |
D2 |
D1 |
D0 |
|
Value |
0x00 |
0x63 |
0x34 |
0x00 |
Calculation into a "real world" value:
value = input data x input_device_period / (4 x 2R35)
value = 0x633400 x 2 µm / (4 x 28)
value = 6,501,376 x 2 µm / (4 x 256) = 0.012698 m = 12.698 mm
The measured value corresponds to the data of the input device, that gives an overall measuring range of 12 mm.