Application

Sequence of Operation
Damper Position on Return from Power Failure
25
Siemens Industry, Inc.
Application Note, App 2927
140-1311
2015-07-07
Network Annunciation
If the LCM is connected to a field panel, alarms can be reported using the workstation
software, or by using a printer that is set up in a building manager’s office to receive
alarms. Points in the controller must be entered in the field panel’s point database
(referred to as unbundling) and defined as alarmable. For example, if the room
pressurization alarm (VOL DIF ALM) is unbundled in a field panel and a pressurization
alarm is triggered, an alarm will be annunciated across the network.
Damper Position on Return from Power Failure
On a return from power failure, the damper-command DOs (DOs 1 through 4) remain
OFF for 5 seconds prior to resuming control. Because of this it is recommended that
the Supply Damper (SUP DMPR DIR) be set for Normally Closed (NCLOSE, closed
when the actuator is retracted) for rooms where negative or neutral pressurization is
required and Normally Opened (NOPEN, open when the actuator is retracted) for
positively pressurized rooms. Likewise, it is recommended that the General Exhaust
Damper (GEX DMPR DIR) be set to NOPEN for rooms where negative or neutral
pressurization is required and NCLOSE for positively pressurized rooms. The default
for the SUP DMPR DIR is NCLOSE. The default for GEX DMPR DIR is NOPEN.
Operation of AVS FAILMODE
AVS FAILMODE is an enumerated point that describes how the supply Damper and
the general exhaust Damper will respond if one or both Air Velocity Sensors (AVS) fail.
It can handle both positively pressurized rooms and negatively pressurized rooms.
The default value of AVS FAILMODE is
0. This default causes both the supply and
general exhaust to hold their current position when an AVS fails. Open Supply, Open
Exhaust and Close Supply, Close Exhaust are not defined AVS FAILMODE states.
AVS Failure and AVS FAILMODE Table Values.
AVS FAILMODE
0
(default)
Hold Supply, Hold General Exhaust
1
Hold Supply, Open General Exhaust
2
Hold Supply, Close General Exhaust
3
Open Supply, Hold General Exhaust
4
Close Supply, Hold General Exhaust
5
Close Supply, Open General Exhaust
6
Open Supply, Close General Exhaust
7
VENTILATION
8
PRESSURE
AVS FAILMODE values are not additive. For example, if AVS FAILMODE equals
3,
this means to open the supply Damper and hold the general exhaust Damper if an
AVS fails.
The first seven values of AVS FAILMODE (0 through 6) describe specific actions taken
when an AVS fails. For example, if AVS FAILMODE equals
5, then whenever an AVS
fails, the supply Damper will always close and the general exhaust Damper will always
open.