off all slaves and enters an idle or standby condition.
4.7.2PERIODIC DATA POLLING MESSAGES
The LL master uses polling to discover new slave Sola devices and to periodically refresh the information it has about a known slave Sola devices. Thereafter it polls the known devices to make sure they are still present and to obtain updated status information. It also periodically polls the entire slave address range to discover any new slave devices. A polled Sola is read to determine the values of the following data items: a. The slave's type (compatibility) as indicated by the Slave type b. The slave enable status Slave enable c. The slave mode as set in Slave mode d. The slave sequence order as set in Slave sequence order e.
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. There are 5 commands that might be sent:
•All slaves are commanded to turn off and remain off.
•The LL master sends message to Solas that are off, to turn their fans on.
•The LL master suspends operation which request a burner to recycle and remain in Standby if it has not yet opened its main valve (e.g. it is in Prepurge or PFEP) but to keep firing if it has reached MFEP or Run. This suspend may be for the fan to be on or off in standby. This message is used to abort the startup of a slave that is not yet firing (because demand went away just before it was firing), but to keep it on if it actually is firing (the LL master will
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Date: 8-4-2010
Revision: 0
Form: 2396
discover what happened in a subsequent status response). The LL master also sends this message to a slave that is OnLeave. (This ensures that if the slave is firing when it returns to LL master control, it will stay that way until the master has decided whether to use it; or conversely, if the slave stops firing for some reason that it will not start up again until the LL master has requested this. In either case, the command will be to turn on the off cycle fan if any other slave burners are firing, or to turn the fan off if the slave is the only slave that might (or might not) be firing.
•The LL master sends message to turn the burner on and to assign the burner’s firing rate. If the commanded modulation rate is less than the burner’s minimum modulation rate, then the burner should always operate at its minimum rate.
4.7.3SLAVE STATUS MANAGER
The LL master keeps track of slave status for each Sola that is enabled as a slave device. The slave status manager operates internally for each slave Sola devices (up to 8). There is a table entry for each device containing the following data:
• SlaveState:
Unknown - indicates the table entry is unused and empty
Available - indicates the slave is OK and ready to use, but is not
currently firing as a slave
AddStage - stage is getting ready to fire SuspendStage - stage was getting ready but is not needed
Firing - indicates the slave is currently firing OnLeave - indicates the slave is operating for some other demand source within it that has higher priority than slave demand.
Disabled - indicates the slave is locked out or disabled in some way
Recovering - indicates the slave is in a time delay to ensure that it is OK before it is again considered to be available.
•RecoveryTime: Saves how long the slave must be OK to recover.
•RecoveryTimer: Used to measure the slaves recovery time
•RecoveryLimitTimer: Enforces a maximum slave recovery time
