User Manual

CM2N8882en / 02.2000 Siemens Building Technologies
6/8 Landis & Staefa Division
Positioning points are analogue output information points. Any status changes result
from operator input and program processes.
Positioning points are also referred to as positioning command points or analogue output
(AO) points.
Positioning points in the plant
•
Primarily consist of electric actuators for modulating or three-position control such as
valve and air damper actuators. These are common positioning signals:
−
Modulating voltage signals (e.g. B. 0..10 V)
−
Modulating current signals (e.g. 4..20 mA)
−
Positioning pulses AC 24 ... 250 V for actuating equipment with three-position response
•
Provide feedback to the system on the present position (optional)
Additionally, positioning points also have a remote/local function which acts on the
modules in parallel to the auto/manual hand switches.
In VISONIK, the positioning modules electrically adjust the positioning signals, i.e., the
digital positioning values transmitted by the VISONIK BPS via the P-bus to the positioning
modules are converted to modulating positioning signals (D/A conversion) or positioning
pulses (pulse time = runtime) in accordance with the positioning module type.
D
A
A
D
1
2
VISONIK BPS
bidirectional
data line
Positioning points
in the plant
P-bus
Communication
partner
Preparation
Processing
8882Z06E
Positionin
g
module
Depending on the programming, positioning command changes may trigger the
following functions in VISONIK:
Function Example
Reports Point status change
Triggering further positioning commands Sequence control
Calculation and issue of new positioning
commands
Functions POS, MIN, MAX, HYS
Display Valve position in plant picture
Transfer of information to various
communication partners
See "Transfer of module point
informationpage 7.
Positioning points
Definition
Design
Positioning module
processing
Functions