Siemens SIMATIC ET 200S Operating Instructions Manual page 39

Pulse Duration when the Comparison Value is Reached
The pulse duration begins when the respective digital output is set. The inaccuracy of the
pulse duration is less than 2 ms.
The pulse duration can be set to suit the actuators used. The pulse duration specifies how
long the output is to be set for. The pulse duration can be preselected between 0 ms and
510 ms in increments of 2 ms.
If the pulse duration = 0, the output is set until the comparison condition is no longer fulfilled.
Note that the count pulse times must be greater than the minimum switching times of the
digital output.
Isochrone mode: In isochrone mode, as well, the DO1 output is switched as soon as the
comparison condition is fulfilled and is therefore independent of the bus cycle. The status of
the virtual output DO2 is signaled at time T
Switch at Comparison Values
The comparator switches the output when the following conditions are met:
• The two comparison values must be loaded using the load functions CMP_VAL1 and
• After the comparison values are loaded, the DO1 output must be enabled with
The following table shows you when the DO1 is switched on or off:
V2 < V1
(see Figure below)
V2 = V1
V2 > V1
(see Figure below)
The comparison result is indicated by the status bit STS_CMP1. You can only acknowledge
and thus reset this bit when the comparison condition is no longer fulfilled.
There is no hysteresis in the case of this output behavior.
It is not possible to control the DO1 output with the SET_DO1 control bit in the case of this
output behavior.
Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
CMP_VAL2, and
CRTL_DO1.
.
i
DO1 is switched on when
V2 ≤ count ≤ V1
V2 = count = V1
V1 > count
or
count > V2
1Count24V/100kHz
2.6 Count Modes
DO1 Is switched off when
V2 > count
or
count > V1
V2 ≠ count ≠ V1
V1 ≤ count ≤ V2
39