Monitoring Functions And Error Messages - Siemens SIMATIC S5 Manual

1.1.5 Monitoring Functions and Error Messages

Setpoints
Two setpoints can be entered for each controller. The setpoint must not exceed the maximum
value.
– If a higher setpoint is entered, an error bit is set and the value is limited to the
maximum value.
– If the second setpoint (lower setpoint) is greater than the first setpoint, it is limited to
the first setpoint and an error bit is set.
Actual values, tolerances
Two upper and two lower tolerances can be set for each controller. The following states can
be monitored:
– Actual value is greater/less than setpoint plus first positive tolerance or setpoint
minus first negative tolerance
corresponding error bit is set.
– Actual value remains within the second tolerance band and returns to the first
tolerance band
the most extreme value reached is stored.
This can be read by the CPU (in message 19 and 20).
– Actual value violates the second tolerance band
depending on the parameter assignment (in message 15) the affected controller
may be disabled.
Fig. 1.1.5/1 Tolerance bands
IP244
C79000–B8576–C860–02
Description of the Firmware
4–11