User Manual

Siemens Building Technologies CM2N8894E 10.1999
Landis & Staefa Division 3/4
The VISONIK BPS has the following two complex controllers:
−
SEQ sequence controller
−
STR adaptive controller
Sequence controllers SEQ allow for creating the following controls through combination
with RGB controller blocks:
Sequence Cascade/sequence
x
°C
8894Z03
RGB
RGB
w
w
RGB
RGB
RGB
x
w
y
w
x
°C
8894Z04
°C
Below is a list of the primary features of the two control types:
Control Features Properties
Sequence Several actuators in
sequence/own
controller block for
each actuator
The controller parameters of each portion can
individually be adjusted to the different
amplifications and time responses.
(e.g., heating and cooling elements, mixing
dampers, etc.)
Cascade/
sequence
Reference controller
plus auxiliary control
loop with one or
several sequential
controllers
The reference controller defines the setpoint for
the sequential controller(s).
For the reference control loop, an upper and lower
limit can be defined.
Influencing variables in the auxiliary control loop
(e.g. supply air) are controlled before reaching the
primary control loop (e.g. room).
The STR (Self Tuning Regulator) adaptive controller is based on the RGB controller
block. The controller parameters are set to meaningful basic values and then adjusted
cyclically and automatically to the current states in the control loop via function STR:
y
STR
w
x
8894Z05E
Control loop
Controller
Setting
requirements
Identification
Controller parameter
Loop parameter
The following steps occur on each call-up of function STR:
1. Identification of the control loop
2. Adjustment of the controller parameters via saved settings
3. Calculation and output of positioning variable y by the controller
Adaptive controllers are used in control loops that vary due to the impact of various
influencing variables. However: Even adaptive controllers cannot handle all complex
control loops (e.g., loops with long dead times).
Complex
controllers SEQ
and STR
SEQ sequence
controller
Features
STR adaptive
controller
Function and use