User Manual

Logical I/O blocks
General functions
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3. The switch-on or switch-off delay timer starts.
4. After expiry of [TiOnMin] or [TiOffMin], priority 6 is set to inactive.
If the delay times [DlyOn] or [DlyOff] are equal to 0, no action is taken.
If the new value which determines [PrVal] is the same as the current [PrVal], then, here too, no action is
taken.
The minimum on/off time
For each change at the output [PrVal] from OFF to Stage n or from Stage n to OFF, the entry for priority 6 is
set up as follows:
If the minimum ON-time [TiOnMin] or OFF-time [TiOffMin] is greater than 0:
1. Priority 6 adopts the new present value [PrVal].
2. Priority 6 is set to active.
3. The timer for the minimum on-time or off-time is started.
4. After expiry of [TiOnMin] or [TiOffMin], priority 6 is set to inactive.
If the minimum switch-times [TiOnMin] / [TiOffMin] are set to 0, no action is taken.
Constraints
● The functions described above are supported only by the BO, MO, BVAL and MVAL blocks.
● With multistage switch commands, the monitoring periods are enabled only when switching from OFF
to Stage n or from Stage n to OFF. When switching from one stage to another (e.g., Stage 1 to Stage 2),
the timer times are not enabled.
● However, any timer times already running will continue to run.
Application
● Unnecessary on/off switching operations can be prevented by activating minimum switch-on or switch-
off times.
● Activating switch-on or switch-off delays ensures that run-on time delays are maintained.
Information bit
In order for a given value to be included in the evaluation of [PrioArr], its information bit must be set.
The following applies to priority 1,4,7 and 15 (data flow connection): The relevant information bit is set via
pins [EnSfty], [EnCrit], [EnSwi] and [EnPgm].
The following applies to priority 2, 5, 8, 14 and 16 (BACnet command system): When a given value is
commanded via BACnet, the value concerned is entered in the [PrioArr] and the associated information bit
is set automatically.
The following applies to priority level 6: Both the value and the information bit are handled by the block
concerned.
Prio Meaning Use Access via
1 Safety value (life safety)
Reserved for the initiation of safety
functions (1 = highest priority).
If priority 1 or 2 becomes the
determining value for [PrVal], then the
value concerned is transmitted
immediately to the [PrVal] output. It is
not subject to the delay times defined
for priority 6.
Local safety function, e.g.:
- Fire
- EMERGENCY OFF
- Service switch
- Gas alarm
- Thermal package
Data flow interconnection via pins:
[ValSfty] and [EnSfty].
Normally, [ValSfty] is a constant and
[EnSfty] can be enabled/disabled.
2 Higher-level safety function, e.g.:
- Smoke extraction
BACnet command system.
Access via the CMD_CTL block.
3 Not used in Desigo.
4 Critical value (plant protection)
Reserved for monitoring critical plant
states.
If priority 4 or 5 becomes the
determining value for [PrVal], then the
value concerned is transmitted
Local monitoring of critical plant states,
e.g.:
- Frost protection (protection from
excess cooling)
- Interlock of aggregates
- Icing protection
Data flow interconnection via pins:
[ValCrit] und [EnCrit].
Normally, [ValCrit] is a constant and
[EnCrit] is enabled/disabled.