Siemens SIMATIC S5 Manual page 101

Data Exchange with the Central Controller
Approximate values (very general):
Notes: If the control zone is too restricted (0 to 4 C) the control action is similar to that
of a purely switching controller (bimetallic controller).
The control zone has nothing to do with the previously described tolerances. The
tolerances are simply for monitoring, whereas the upper and lower limits of the
control zone are controller parameters.
Fig. 2.1/2 Upper and lower control zones
Examples
a) With zone control, bit 1 in control byte 2 = 0
ZONOB
ZONUN
Setpoint
Control zone
b) No zone control active, bit 1 in control byte 2 = 1
ZONOB
ZONUN
Setpoint
Control zone
c) Setpoint ramp, bit 1 in control byte 2 = 1
ZONOB
ZONUN
Setpoint
Control zone
The setpoint is reached in 1.5 hours following the ramp slope if the previous actual value was 0 C.
4–34
= 20 C
= 30 C
= 200 C
= 170 C to 220 C
= 1600 C/h
= 1600 C
= 220 C
= 0 to maximum value (in C)
= 200 C/h
= irrelevant
= 300 C
= 0 to maximum value (in C)
IP244
C79000–B8576–C860–02