Siemens SIMATIC S7-300 FM 350-1 Manual page 154

Operating Modes, parameters and commands
7.4 Measuring modes
Behavior of the Digital Outputs
Digital output DO0
For digital output DO0, you can set 4 possible reactions to reaching the limit values. The
various options are shown in the table below.
Table 7- 44 Behavior of Digital Output DO0
Parameterization of
Digital output DO0
No comparison Not affected by the monitoring of limit values.
If Output DO0 is already set, it can be reset by
changing the parameter to "No comparison".
You can use Output DO0 freely as a digital output
and set and reset it with the control signal SET_DO0
if you have enabled it with the control signal
CTRL_DO0.
Out of limits DO0 is set in both of the following cases:


Below the low limit DO0 is set if

Above the high limit DO0 is set if

Digital output DO1
You can use Output DO1 freely as a digital output and set and reset it with the control signal
SET_DO1, provided that it has been enabled.
DO1 is not affected by limit value monitoring.
In non-isochronous mode, DO1 switches immediately after the output is set or reset.
In isochronous mode, DO1 switches at the end of the update time at time T
154
Behavior of Digital output DO0
Measured value < Lower limit
Measured value > Upper limit
Measured value < Lower limit
Measured value > Upper limit
Switching time
Isochronous mode
To point in time T . Immediately after
o
setting or resetting
the output
At the end of the At the end of the
update time at time update time
T
i
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01
Non-isochronous
mode
.
o