Filter operation

Velocity Filter (index 0x80p8:18)

The EL5032 (from FW16) and EL5032-0090 terminals are equipped with a digital filter that can assume the characteristics of an Infinite Impulse Response filter (IIR filter). The filter is disabled by default (value: "0" (None)).

IIR filter

The filter with IIR characteristics is a discrete time, linear, time invariant filter that can be set to eight levels (level 1 = weak recursive filter, up to level 8 = strong recursive filter).
The IIR can be understood as a sliding average value calculation after a low-pass filter.
Here, the IIR filters work cycle-synchronously and are thus updated depending on the cycle time.

Filter operation 1:

IIR filter

Difference equation: Yn = Xn * a0 + Yn-1 * b1
with a0 + b1 = 1
a0 = (see table)
b1 = 1 - a0

Velocity Filter
0x80p8:18

Value

PDO update time

Filter property

Comment

Rise time
10-90%
[samples] (typ.)

0

None

-

-

Filter disabled

-

1

IIR 1

Cycle-synchronous
(up to min. 100 µs)

Low-pass filter

a0 = 1/21 = 0.5

3

2

IIR 2

a0 = 1/22 = 0.25

8

3

IIR 3

a0 = 1/23 = 0.125

17

4

IIR 4

a0 = 1/24 = 0.0625

34

5

IIR 5

a0 = 1/25 = 0.03125

69

6

IIR 6

a0 = 1/26 = 0.015625

140

7

IIR 7

a0 = 1/27 = 0.0078125

280

8

IIR 8

a0 = 1/28 = 0.00390625

562

Filter operation 2:
Rise time T 10 – 90% (typ.)