Application

Sequence of Operation
Application Notes
39
Siemens Industry, Inc.
Application Note, App 2926
140-1308
2015-07-07
NOTE:
If desired, the LCM can be used without any fume hoods attached. In this case, MAX
HOOD VOL should be set to 0 cfm to disable the alarming that would occur if the
fume hood flow input drops below 1 Vdc.
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.
Discharge Temperature Sensor – Temperature control is lost and BTU calculations
cease if the discharge temperature analog input point, DISCH TEMP fails. This is
because the temperature loop stops updating and the discharge loop stops operating.
Application Notes
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 0.
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
show as Failed.