Siemens SIMATIC S5 Manual page 137

Data Exchange with the Central Controller
Bytes 16 to 28
Error bytes 0a to 12a
Bit 0 Parameter assignment error (system parameters):
The bit is set if in control byte 1, bit 2 is 1, the self-tuning function is not currently
active and you have entered zero in the messages for the parameters "slope" or
"delay time".
Bit 1 Parameter monitoring:
This bit is set if main control byte 1, bit 2 is 1 and the parameter monitoring
(oscillation detector, see Section 1.2.1) is not active.
If the oscillation detector has changed the controller gain and the integral action
time by a factor totalling 2.9, the oscillation detector switches itself off for this
controller. In this case, the oscillation detector has either reacted to two weak
oscillations, or one strong oscillation, or one weak and one strong oscillation..
The bit is not set if the setpoint is zero or the heating switch is OFF. The oscillation
detector is reactivated as soon as the self-tuning function has been called again
for the controller and the function has calculated parameters, or when main control
byte 1, bit 2 is 1 following a cold restart.
If the oscillation detector changes the parameters, the parameters stored in the
message remain unchanged.
If bit 7 in main control byte 2 is set, the parameter monitoring bit is not set.
4–70
IP244
C79000–B8576–C860–02