Siemens SIMATIC ET 200S Operating Instructions Manual page 150

1Count5V
3.6 Count Modes
Isochronous mode: In isochronous mode, as well, the DO1 output is switched as soon as the
comparison condition is fulfilled and is therefore independent of the bus cycle.
Figure 3-13
Figure 3-14
Setting or Modifying the Function and Behavior of the Digital Output DO1
When setting or modifying the behavior of DO1, you must take all assignable
interdependencies into account. Failure to do so will generate a parameter assignment error
or a loading error.
Boundary conditions:
If you assign "Switch at Comparison Values" for DO1, you must:
● Set hysteresis = 0, and
● Assign "Output" for the DO2 output
Hysteresis
An encoder can remain at a particular position and then fluctuate around this position. This
state causes the counter status to fluctuate around a particular value. If there is a
comparison value in this fluctuation range, for example, the associated output is switched on
and off in accordance with the rhythm of the fluctuations. The 1Count5V is equipped with
programmable hysteresis to prevent this switching in response to small fluctuations. You can
assign a range between 0 and 255 (0 means: hysteresis switched off).
Hysteresis also works with overflow and underflow.
150
V2 < V1 at the Start of Counting
V2 > V1 at the Start of Counting
Technological Functions
Operating Instructions, 06/2010, A5E00124867-07