Parameter Assignment For Cascaded Control; Changes/Additions To The Messages - Siemens SIMATIC S5 Manual

Special Functions for Plastic Machines

3.2.4 Parameter Assignment for Cascaded Control

If cascaded control is selected, the information in the messages 0 to 12 changes. Message 0 and
therefore controller 0 is always assigned to the master controller. The 12 subordinate zone
controllers are assigned messages 1 to 12. The structure of these changed messages can be found
in Figs. 3.2.6/3 and 3.2.6/4.

3.2.5 Changes/Additions to the Messages

Message 0 for the master controller:
Bytes 0/1 (material temperature setpoint) and bytes 2 and 3 (positive and negative tolerance) are
the same as for conventional controllers. A second setpoint and the corresponding tolerances
(bytes 4 to 7) are omitted.
Control byte 1 must be set as follows:
Bit 0: always
Bit 1: switch
Bits 2 to 7: always
Control byte 2 must be set as follows:
Bit 0: always
Bit 1: always
Bits 2 to 7: always
The controller gain (bytes 16/17), the integral action time (bytes 18/19) and the control zones (bytes
24 to 27) are the same as for standard controllers.
The values for the derivative action time (bytes 20/21), heating/cooling ratio (byte 28) and response
value (byte 29) are omitted.
Messages 1 to 12 for the secondary controllers:
Messages 1 to 12 for the secondary controllers have a form identical to that of the messages
described in the operating instructions. The following special features must be noted.
SBn is the active setpoint of the individual controller. Bit 1 of control byte 1 corresponds to switches
S1 to S12 in Fig. 3.2.6/1. If bit 1 is set, the controller is influenced by the master controller. If bit 1
= 0, the controller operates independently of the master and can therefore be used for other
purposes. The evaluation factor and limitation value (see below) are then irrelevant. Setpoint
ramping is not possible.
The limitation value (byte 11) specifies how many per mil of the entered setpoint (bytes 0/1) of
the controller the setpoint correction can be after evaluation. The value must be in the range from
0 to 255 per mil.
4–76
0 (2-step controller)
S0 "OFF" (0) or "ON" (1)
0
0 (no manual operation)
0 (no setpoint ramping possible)
0
IP244
C79000–B8576–C860–02