Eaton easy800

5 Function blocks
5.14 FT, signal smoothing filter
194 Control Relay easy800 11/11 MN04902001Z-EN www.eaton.com
Response of the function block
The step response of the FT function is an e function. After a time t = T
g
the
normalized output value is 0.63 QV/QV
max
.
Figure 133:Figure: Step response of the FT function block
The function block operates according to the following equation:
Y(t) = [T
a
/T
g
] x [K
p
x (x(t) - Y(t-1))]
Y(t) = Calculated output value for scan time t
T
a
= Scan time
T
g
= Recovery time
K
p
= Proportional gain
x(t) = Output value with scan time t
Y(t–-1) = Output value with scan time t - 1
Scan time:
Scan time T
a
depends on the set recovery time value.
Memory
56 + per 4 Byte/Constant at function block input
Cycle time [μs]
easy800 standard easy800-SWD
60 15
￫
The function block updates the output value every time recovery
time T
g
expires.
Recovery time T
g
Scan time T
a
0.1 s - 1 s 10 ms
1 s - 6553 s
0.01 T
g
QV/QV
max
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0120.1
0.63
1.5
2.5
t/T
G