Siemens SIMATIC S5 Manual page 121

Data Exchange with the Central Controller
Bit 2 The whole module is re-initialized with the values stored in messages 0 to 15 and
30 to 42 (requires FB 162 for the data exchange with the commands "PA" and
"PZ").
Bit 3 Trigger bit for measured value acquisition once at channel 14, resets
acknowledgement bit 2
FB 162).
Bit 4 Must be set if the manipulated variable averaged over the monitoring time (byte
2/3 in message 15) is to be output while a thermocouple is out of action. This is
common to all controllers. (See commands "G1", "G2": FB 162).
Bit 5 When this bit is set, the lower setpoint is used instead of the temperature setpoint
(lower "night" temperature). (See commands "S1", "S2": FB 162).
Bit 6 Free
Bit 7 If the actual value of a controller is outside the second tolerance and bit 7 is set,
the affected controller is disabled if the actual value had been within the first
tolerance band at least once following a setpoint change.
Bit 7 is set or reset in the FB 162 using the commands "T2" or "T1".
When the actual value returns to the second positive tolerance band, the controller
automatically resumes operation.
To simplify operation with function block FB 162, bits 0, 1, 2 and 3 are stored individually a second
time in the main control bytes 4a, 4b, 4c and 4d.
You do not need to set or reset bits 0 to 3. This is performed automatically by the function block.
4–54
3
in status byte 1, message 16 (see Direct Functions:
IP244
C79000–B8576–C860–02