User Manual

Logical I/O blocks
General functions
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The trigger function is used, e.g., for the integration of LON data points. Owing
to the event mechanism, this function is not used for P-bus objects.
The
Switch setting is used to generate an ON or OFF pulse of a predefined
duration. A command via BACnet, or the activation of an Enable signal in one of
Priorities 7…16 via the data flow connection initiates an associated pulse
(event). The minimum switch-on time [TiOnMin] and/or minimum switch-off
time [TiOffMin] must be set. Setting both times can prevent fast switching
operations. Priorities 1…5 have a blocking effect.
The
Pushbutton with delay function is like the Switch function, except an active
pulse can be extended by another pulse at any time.
Runtimes and monitoring periods
The I/O function blocks are designed for the runtimes and monitoring periods
required in HVAC engineering, and can therefore be used directly as
components (motors, dampers, fans, etc.).
Different runtimes and monitoring periods can be set, depending on the
function concerned.
Runtimes:
● Switch-on/off delay
● Minimum switch-on/off time
● Ramp-up/-down time
Monitoring periods:
● Feedback time with switch-on/off
● Feedback signal deviation during operation
Runtimes
Blocks: BO, MO, BVAL, MVAL
The switch-on/off delay when applied to the switching I/O blocks causes a
delayed output if the switch command was written via Priority 7…16. The delay
time affects Priority 6 as described. Switch commands via Priorities 1…5 are
executed without a delay.
When applied to the switching I/O blocks, the minimum switch-on/switch-off
time causes the output to be blocked for a period of time if the switch
command was written via Priority 7…16. The minimum switch-on/off time
affects Priority 6 as already described in Section 24.2.1.3. However, switch
commands via Priorities 1…5 are executed immediately irrespective of the
minimum switch-on/off time.
The ramp-up/down times (run-up/-down times) can be defined in a table for
each stage. These times apply to the two switch types [SwiKind]
Normal and
Motor .
The ramp-up time is the time taken by a motor when changing from a lower
speed to the next higher speed, to reach the new speed. This limits the current
consumption of the motor.
The ramp-down time is the time taken by the motor when switching down from
a higher speed, to reach the lower speed. This prevents feedback to the mains
supply network and protects the fan belt and the motor.
As a rule, the ramp-up and ramp-down times depend on the centrifugal mass
involved, and must be determined separately for each project.
Especially with single-speed motors, the times can be used as Open/Close
runtimes (e.g., damper actuator from 0…100%). A moving damper can thus be
mapped in the system and the transition signal can, if required, be used for
control purposes.
Monitoring periods
Blocks: BI, MI, BO, MO, BVAL, MVAL
Switch
Pushbutton with delay
(time extension)
Switch-on/off delay
Minimum switch-on/off
time
Ramp-up/down time
Feedback monitoring /
process value
monitoring