Siemens SIMATIC S5 Manual page 96

Example 2
2-step controller (heating controller) without substitute thermocouple/Pt 100 with manual operation
and zone control, heating switch not effective.
Control byte 1 = 00H; control byte 2 = 05H
Example 3
Example 3-step controller with substitute thermocouple/Pt 100 connected to channel 7 with setpoint
ramping, without manual operation, heating switch effective.
Control byte 1 = 79H, control byte 2 = 02H
Byte 10 Manual manipulated variable
If the controller is to be operated manually, bit 0 in control byte 2 must be set (1).
Instead of the manipulated variable calculated by the controller, the manipulated
variable entered by the operator as a percentage is used for the pulse-duration
output. If the output for cooling is to be addressed with 3-step controllers,
128 must be added to the required percentage.
Example:
If a sensor fails, it is possible to avoid switching off the process by changing to
manual operation. By updating the controller integrator, the switchover to
automatically controlled operation after replacing the defect sensor is bumpless.
Bit 0 in control byte 2 must be reset.
At the FB 162 the command "HB" is used to enable manual operation, the
command "AB" to disable manual operation.
Byte 11/12 For explanation see "cascaded control" (Section 3.2)
Byte 13 Free
Byte 14/15 Sampling time
The time base for the controller sampling time depends on the ADC conversion
time and the number of analog inputs to be converted. These inputs must also be
counted when controllers are disabled by entering setpoint = 0.
The following tables show the time base:
a) In normal operation including cascaded control
IP244
C79000–B8576–C860–02
Data Exchange with the Central Controller
control byte 1
control byte 2
manual manipulated variable
manual manipulated variable
= 01 Hex (3-step controller)
= 01 Hex (manual operation)
= 60 (heating at 60 %)
= 168 (cooling at 40 %)
(40 + 128 entered)
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