Application

Sequence of Operation
Active Flow Minimums and Maximums
11
Siemens Industry, Inc.
Application Note, Application 6759
140-1335
2015-07-07
The following table shows what is enabled when OCC ENA is at a particular value.
OCC ENA Values.
OCC ENA (value)
Description
0
(default)
Both OCC BUTN DI1 and OCC SWIT DI2 are disabled.
1
Only OCC BUTN DI1 is enabled.
2
Only OCC SWIT DI2 is enabled.
NOTE:
OCC ENA does not allow both OCC BUTN DI1 and OCC SWIT DI2 to be enabled at
the same time. If OCC ENA is set greater than 2, it will default to 0.
OCC SWIT DI2 – The occupancy switch (dry contact switch in the room) can be any
device that closes the switch when the room is occupied (occupancy sensor, extra
contact on light switch, and so on). The controller uses this input for occupancy if the
setup point OCC ENA is set to 2. Otherwise, OCC SWIT DI2 does not affect
occupancy.
OCC BUTTON – Some thermostats include a momentary switch with a push button.
The controller can use this button as a source of occupancy commands if the setup
point, OCC ENA, is set to
1.
When the room sensor button is pushed, the controller interprets this as a request to
change the occupancy status of the room. If the room is unoccupied, it changes to
occupied. If it is occupied, it
may switch to unoccupied, depending on the states of the
other occupancy sources. The current request status of the room sensor button is
indicated by BUTTON CMD. This point is used to investigate the room sensor button’s
effect on the occupancy status of a room.
OCC BUTTON does not provide that information because it is connected to a
momentary switch.
Active Flow Minimums and Maximums
When OCC.UNOCC equals OCC:
 The active supply airflow minimum equals OCC SUP MIN.
 The active supply airflow maximum equals OCC SUP MAX.
 The active general exhaust airflow minimum equals OCC GEX MIN.
 The active general exhaust airflow maximum equals OCC GEN MAX.
When OCC.UNOCC equals UNOCC:
 The active supply airflow minimum equals UOC SUP MIN.
 The active supply airflow maximum equals UOC SUP MAX.
 The active general exhaust airflow minimum equals UOC GEX MIN.
 The active general exhaust airflow maximum equals UOC GEN MAX.