Application

Sequence of Operation
Application Notes
28
Siemens Industry, Inc.
Application Note, App 2923
140-1347
2015-07-07
Laboratory Room Controller – If the LCM power fails, all actuators default to their user-
defined fail-safe states. Since there is no power to the controller, no LEDs are
available.
Electronic Actuator – If the actuator fails, typically, flow control is lost and alarms are
triggered.
Upon loss of power or control signal to the actuator, it will move to its fail-safe position.
Room Temperature Sensor – If the room temperature sensor fails while CTL TEMP is
not overridden or is not being adjusted by a field panel, then ROOM TEMP and CTL
TEMP both display as “Failed” and temperature control is suspended at the current
value of TEMP LOOPOUT. If ROOM TEMP is unbundled in a field panel and defined
as alarmable, an alarm will be annunciated across the network.
If the room temperature sensor fails while CTL TEMP is overridden or is being adjusted
by a field panel, then ROOM TEMP displays as “Failed”. CTL TEMP will continue to be
overridden or adjusted by the field panel and room temperature control proceeds as
normal. CTL TEMP will continue to have a status of NORMAL. If ROOM TEMP is
unbundled in a field panel and defined as alarmable, an alarm will be annunciated
across the network.
Room Temperature Setpoint Dial – If the room temperature setpoint dial fails while CTL
STPT is not overridden or is not being adjusted by a field panel, then ROOM STPT and
CTL STPT both display as “Failed” and the last known good value of ROOM STPT is
used to determine the current value of CTL STPT. The rest of the room temperature
PID loop is unaffected by the setpoint dial failure. If ROOM STPT is unbundled in a
field panel and defined as alarmable, an alarm will be annunciated across the network.
If the room temperature sensor fails while CTL STPT is overridden or is being adjusted
by a field panel, then ROOM STPT displays as “Failed”. CTL STPT will continue to be
overridden or adjusted by the field panel and room temperature control proceeds as
normal. CTL STPT will continue to have a status of NORMAL. If ROOM STPT is
unbundled in a field panel and defined as alarmable, an alarm will be annunciated
across the network.
Application Notes
Supply Only - Operating Without a General Exhaust Box
This application can operate without a general exhaust box. If a general exhaust box is
not being controlled, set TRACK METHOD to FLOW and set the following points:
 TRACK MODE to 3.
– Without a fume hood attached, use a value of 3 = ETS (exhaust tracks supply)
Flow Tracking, should be used for both the occupied and unoccupied modes.
– With a fume hood attached, use a value of 0 = STE (supply tracks exhaust)
Flow Tracking, should be used for both the occupied and unoccupied modes.
 GEX FLO COEF to 0.
When GEX FLO COEF equals 0, GEX AIR VOL will always read 0, but will never
display as Failed.
 OCC GEX MIN and UOC GEX MIN to 0.
If these two points are not set to 0, GEX AIR VOL— will read 0 since GEX FLO
COEF was set to 0—will be less than the general exhaust box minimum, resulting
in a false ventilation alarm.
 OCC GEX MAX and UOC GEX MAX left at default or a higher value.
These two points should be set to the highest value: 1) default or 2) OCC SUP
MAX / UOC SUP MAX – small values will result in the supply box not being able to
reach higher flow setpoints.