Falcon Lead Lag Appendix E
E-46
The Slave Command register is writable but it is mostly ignored, however the Aux pump X, Y, and Z are effective
for any setting of the Slave enable parameter.
The Enable for Falcon Master option Slave write and Slave read parameters; if "Enable for Falcon Master" is not
selected, then these parameters are disabled.
SLAVE MODE: USE FIRST, EQUALIZE RUNTIME, USE LAST
If set to Use First, then this Falcon will be used prior to using other Falcons with other values.
If set to Equalize Runtime, then this Falcon will be staged according to a run time equalization algorithm. (Any unit
set to Use First will precede any that are set to Equalize Run time.)
If set to Use Last, then this burner will be used only after all Use First and Equalize Runtime units have been
brought online.
SLAVE SEQUENCE ORDER: 0-255
Slave sequence order is used to determine the order in which Falcons will be used (staged on) for those Falcons
which the same Slave mode setting. Numbers may be skipped, that is 3 will be first if there is no 1 or 2.
Note: For Equalize Runtime purposes, 1 does not mean the Falcon will be used first every time; that will vary over
time based on the master's run time equalization scheme. In this case the sequence number determines the rela-
tive order in which
Falcon controls will be used in a round-robin scheme.
If the slave sequence number value is zero, then the slave Falcon's ModBus address will be used instead.
If two Falcons which are set the same mode both have the same sequence number then an alert will occur and the
order in which they are used will be arbitrary and is not guaranteed to be repeatable.
DEMAND-TO-FIRING DELAY: MM:SS OR NONE
This delay time is needed by the LL master to determine the length of time to wait between requesting a slave
Falcon to fire and detecting that it has failed to start. It should be set to the total time normally needed for the burner
to transition from Standby to Run, including such things as transition to purge rate, prepurge time, transition to ligh-
toff rate, all ignition timings, and some extra margin.
BASE LOAD RATE: RPM OR %
This specifies the preferred firing rate of a burner, which is used for some types of control algorithms.
FAN DURING OFF-CYCLE RATE: RPM OR % (0=DISABLE)
This determines if or where the fan is to be operating during the standby period.
LL MASTER OPERATION AND SETUP
LL master operation is subdivided into the following functions:
• Overall control - The LL master has parameters that enable and disable its operation.
• Periodic data polling - The LL master uses polling to discover new slave Falcon devices and to periodically refresh
the information it has about a known slave Falcon devices.
• Slave control - the LL master sends each active slave a command and also performs a slave status read for each
known slave device. It also sends a Master status broadcast that is heard by all slaves.
• Slave status manager - The LL master keeps track of slave status for each Falcon that is enabled as a slave
device.
• Demand and priority - different sources of demand can cause the LL master to operate in different ways. These
sources have a priority relationship.
• Modulation - each demand source has one or more setpoints that may be active and an operation sensor. These
are used to detect turn-on and turn-off conditions. The difference between operating point and setpoint determines
the LL master's firing rate.
• Stager - the stager determines when slave Falcons should turn on as the need for heat increases, and when they
should turn off as the need for heat decreases.Rate allocation - the PID block's output is used to determine the
firing rate of each slave unit using various rate allocation techniques.
• Add-stage methods - various methods can be used to determine when a new stage should be added.
• Drop-stage methods - various methods can be used to determine when a stage should be dropped
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