Curtis 1234/36/38 Manual, Rev. D
93
1 1 J U LY 2 0 0 8 D R A F T
7 — VCL
This allows the VCL to either multiply (Throttle_Multiplier > 128) or divide
(Throttle_Multiplier < 128) the nominal throttle value. Typically the default
multiplier is set to 128, thus having no net effect. Both Throttle_Multiplier
and Throttle_Offset can be positive or negative.
The output of the multiplying and summing nodes is a VCL variable
called Mapped_Throttle, which is displayed in the 1311 Monitor » Inputs menu.
Checking the value of Mapped_Throttle using the 1311 is a good way to see if
your Throttle Menu parameters are set correctly. A VCL program can control
the throttle by changing the variables VCL_Throttle (only if Throttle Type =
5), Throttle_Multiplier, and Throttle_Offset. The effect of these variables can
be observed as Mapped_Throttle in the 1311 Monitor » Inputs menu.
Mapped_Throttle next passes through a limiter that is active only if a pump
motor is being operated (Pump Enable = On, see page 33). When active, this
function limits the throttle signal to only positive (forward) motion, which is
appropriate for controlling a hydraulic pump motor.
The throttle signal continues to a selector switch that will set the throttle
signal = 0% if any of the following conditions is present: Interlock_State = Off
(see page 64), a fault has set throttle request = 0% (see the Troubleshooting
Chart, Table 5), or if Main_State
≠ 5 or 10 (see page 69).
After this selector switch the throttle signal is a VCL variable called
Throttle_Command, which is displayed in the 1311 Monitor » Inputs menu.
Throttle_Command is the final value of the throttle signal chain that is input
to the Control Mode Processing block; see Figure 15. Checking the value of
Throttle_Command using the 1311 is a good way to see the final throttle sig-
nal. If ABS(Throttle_Command) > 1 count, the motor controller will output
signals to the motor to make it spin.
For investigating why a motor is not spinning, it is useful to use the
1311 to check the state of the throttle signal from beginning to end: using
Throttle_Pot_Raw, Mapped_Throttle, and Throttle_Command. Once these
values are known, the Motor Command Diagram (Figure 14) can be used to
find how that signal progressed from input to final value.
The following throttle processing variables are accessible by VCL:
VCL VARIABLE ACCESS DESCRIPTION
Throttle_Pot_Raw Read Only Voltage measurement at pin 16, scaled for
the proper wiring
Throttle_Pot_Output Read Only Throttle pot input value after being scaled for
the proper wiring. For use in VCL program
when Throttle Type = 5.
OS_Throttle Read Only Throttle pot value after mapping, to be used in
VCL when VCL Throttle Enable = On and
Throttle Type = 1–4
Mapped_Throttle Read Only Throttle pot value after mapping
VCL_Throttle Read/Write VCL-accessible throttle command
Throttle_Multiplier Read/Write Multiplies or divides the throttle signal
Throttle_Offset Read/Write Provides a +/- offset to the throttle signal
Throttle_Command Read Only Command resulting from throttle processing
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