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Analog Modulation Parameters
These parameters are used only when 4-20mA or 0-10V is selected for modulation output.
Pump Control
The pump control system operates three pumps identified as
Pump A, Pump B, and Pump C. There are multiple pump
control functions which may be attached to any of these pump
outputs. If a function is not attached to a pump, then it has no
effect except that it still will provide input to another pump
function.
It is possible (although not necessarily useful) to attach
multiple functions to the same pump. If this occurs then the
pump will be on if either function requests the pump to be on
(i.e. a logical OR).
Central Heating (CH) Pump
The CH pump function is implemented as shown in Fig. 18.
The CH pump function turns on with overrun time for CH
demand and LL slave demand, assuming that the burner is
neither locked out nor in an anti short cycle delay, however,
these are optionally forced off by CH anticondensation. The
CH pump turns on without force-off and using a separate
overrun timer for CH frost protection. It turns on with neither
force-off nor overrun when outlet high limit is active.
Fan gain up 1-100
This is the gain for speeding up the fan.
Fan gain down This is the gain for slowing down the fan.
Fan speed-up ramp RPM per second
Whenever the burner is firing it will be commanded to increase its RPM no faster than the
rate provided by this parameter.
Fan slow-down ramp RPM per second
Whenever the burner is firing it will be commanded to decrease its RPM no faster than the
rate provided by this parameter.
Fan min duty cycle duty%
The fan modulation output will never send a duty cycle lower than this threshold, except for a
0% duty cycle to turn the fan off.
This can be used to limit the minimum PWM to a level that prevents stalling of the fan. During
start-up conditions the fan speed is monitored by the burner control which will react if it is not
correct. Additionally, during Run if an out-of-range fan speed is reported for more than 3
seconds then the burner control will recycle back to Standby (and try again).
Table 23. Fan Speed Modulation Parameters.
Parameter Comment
mA modulation slope
mA modulation intercept
V modulation slope
V modulation intercept
n
These parameters support factory calibration of the current and voltage outputs by specifying
the slope and intercept of the function that can be used to convert the desired output into the
appropriate PWM duty cycle.
Analog output hysteresis n
This parameter adjusts the amount of hysteresis appliled to the PID output when a non-PWM
modulation is selected. The "n" value determines how much the PID is required to change in
a new direction before the output will change.
This is somewhat experimental, although simulation shows this technique provides better
response and also better control of motor reversals than a deadband.
A typical range is 0 (disabled) to 10, although higher values are allowed. The amount of PID
change required to change direction is computed as:
n/10 * Pgain * P scaler
Background: The granularity of temperature measurement in the Falcon is 0.1C, which is
represented internally as an integer (e.g. C * 10). Thus if the temperature changes by the
smallest measurable amount (e.g. 1 count), per P term of the PID output will contribute a
change of 1*Pgain * P scaler, to the total PID output. The parameter thus allows some
fraction of this change to be the threshold for changing direction, e.g. "n" = 5 means0.5 or half
of this amount of change would be needed to change direction. If the Igain is zero then using
any value of "n" less than 10 makes no difference; however when Igain is non-zero it also
contributs to the PID output, so smaller amounts of hysteresis make sense. Experimentally,
values of between 5 to 10 seem to work well.
Table 22. Fan Speed Modulation Parameters. (Continued)
Parameter Comment
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