ABB ACS 800 Series, Application Manual

Page: 26 / 44

Function blocks
26
Operation The block uses input I1 as a reference value. The step values (inputs I2 and I3)
increase or decrease the output O as long as the output differs from limit I1. When O
= I1, the output remains steady.
Input I1: Reference value
Input I2: Step to positive direction (step/sec). Increase the output, when O < I1.
Input I3: Step to negative direction (step/sec). Decrease the output, when O > I1.
O
n
= O
n-1
+ I2 when I1 > O
O
n
= O
n-1
- I3 when I1 < O
O
n
= I1 when I1 = O
Example:
Input I1: 0 -> 150 -> -100 ->0
Input I2: 100 step/sec
Input I3: 10 step/sec
Output:
Going up: Ramp step from Input I2
Going down: Ramp step from Input I3
Connections Input I1, I2 and I3: 24 bit integer values (23 bits + sign)
Output (O): 24 bit integer (23 bits + sign)
Note: The internal calculation uses 48 bits accuracy to avoid offset errors.
time
Input I1
0
150
-100
time
Output
0
150
-100
100 step/sec
100 step/sec
10 step/sec