Siemens SIMATIC S7-300 FM 350-1 Manual page 113

Switching to Comparison Values
Output DO1 switches at two comparison values if the following conditions are fulfilled:
● You have set the behavior of DO0 to "Inactive".
● You have set the behavior of DO1 to "Active for switching to comparison values".
● You loaded both comparison values CMP_V1 and CMP_V2.
● You have enabled output DO1 with CRTL_DO1.
The following table shows when DO1 is activated and deactivated:
Table 7- 22
Comparison values
CMP_V1 and CMP_V2
CMP_V1 < CMP_V2
CMP_V1 = CMP_V2
CMP_V1 > CMP_V2
The result of the comparison is indicated by the status bit STS_COMP2.
You cannot acknowledge and thus reset the status bit STS_COMP2 until the comparison
condition is no longer fulfilled.
The status of the DO1 output is indicated by the status bit STS_CMP2.
There is no hysteresis with this output behavior.
With this output behavior, it is not possible to control output DO1 with the SET_DO1 control
bit.
Figure 7-17
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01
Output DO1 Switch to comparison values
DO1 is activated if
CMP_V1 ≤ Counter level ≤
CMP_V2
CMP_V1 = Counter level =
CMP_V2
Counter level < CMP_V2
or
Counter level > CMP_V1
At the start of the counting process, V2 > V1
Operating Modes, parameters and commands
DO1 is deactivated if
Counter level < CMP_V1
or
Counter level > CMP_V2
CMP_V1 ≠ Counter level ≠
CMP_V2
CMP_V2 ≤ Counter level ≤
CMP_V1
7.3 Count modes
113