Advantech PCL-832, Руководство пользователя

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Chapter 3 Operation 21
The scaling gain
Each of the three PCL chips has its own scaling gain. The scaling gain
lets you set the gain for each channel independently, and enables the
use of different gains accross different applications. The scaling gain
works as follows: when the SG is 1, the Error Counter is stepped up/
down with every pulse from the DDA pulse generator or the encoder
feedback. When the scaling gain is n, where 1 < n < 64, the Error
Counter will only be updated with every n
th
pulse. A larger scaling
gain reduces the system response, and position accuracy is ±n counts.
The Error counter
Each channel also has an independant 13-bit error counter. This
counter records the difference between the number of desired motor
movements, and the actual movements as registered by the servo
motor's encoder. The output of the error counter drives a DAC (digital-
to-analog convertor) which in turn is output to the servo motor driver.
The layout of the error counter is as follows :
Error counter register format
B15 B14~B12 B11 ~ B0
D I R N / A E11 ~ E0
B15 ~ B0 Bit numbers
DIR DDA pulse direction
0 - clockwise (CW)
1 - anti-clockwise (CCW)
E11 ~ E0 Error counter value
As previously discussed, the error counter will accumulate with
actual/desired pulse differences. When the error counter reaches its
limit (4095 if direction is 0, <0 if direction is 1), an overflow error
occurs and the counter is cleared. You will need to reset the PCL-832
when this happens.