Specifications

Curtis PMC 1223/33, 1225/35, 1227/37 Manual
36
3 — PROGRAMMABLE PARAMETERS
THRTL DEADBAND [default access: OEM]
The throttle deadband parameter defines the throttle pot wiper voltage range
that the controller interprets as neutral. Increasing the throttle deadband setting
increases the neutral range. This parameter is especially useful with throttle
assemblies that do not reliably return to a well-defined neutral point, because it
allows the deadband to be defined wide enough to ensure that the controller goes
into neutral when the throttle mechanism is released.
Examples of deadband settings (20%, 15%, 8%) are shown in Figure 20,
along with the formulas used to determine the wiper voltage range (with respect
to B-) that the controller will interpret as neutral.
The programmer displays the throttle deadband parameter as a percentage
of the nominal throttle wiper voltage range and is adjustable from 5% to 30% in
0.5% increments. The default deadband setting is 8%.
The nominal throttle wiper voltage range is 4 volts (from 0.5 V to 4.5 V)
when measured relative to B-. This is true regardless of whether a single-ended or
wigwag throttle is used. When a single-ended throttle is used, the deadband
parameter sets a single threshold wiper voltage—that is, a wiper voltage (relative
to B-) at which the controller will begin to modulate. When a wigwag throttle
is used, the deadband parameter sets two threshold wiper voltages, one on either
side of the 2.5 V (2.5 kΩ) centerpoint, for forward and reverse.
NOTE: The throttle characteristics are defined in terms of wiper voltage
rather than throttle pot resistance because of the range of pot values that can be
used and the variation between pots of the same nominal value. The voltage
Fig. 20 Effect of adjusting the neutral deadband parameter.
Single-Ended Throttle
Wigwag Throttle
0 5V
0.8V
20% Deadband
15% Deadband
8% Deadband
1.1V
1.3V
0 5V
2.2V 2.8V
2.34V 2.66V
2.1V 2.9V
2.5V
KEY:
Neutral 0% 100%
Deadband output output
Notes: Voltages shown are at the pot wiper relative to B-.
Voltages are relative to a nominal 5kΩ pot.
0.5V
0.5V
0.5V 4.5V
4.5V
4.5V
4.5V
4.5V
4.5V
V
DB
= 0.5V + (DB%) (4V) V
DB
= 2.5V ± (0.5) (DB%) (4V)
0.5V