Wesley BC-620-4CA - Manual (Page 95)

Curtis 1234/36/38 Manual,
OS
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2 3 J U LY 2 0 0 8 D R A F T
7 — VCL
AnalogOut uses the same Put_PWM() and Automate_PWM() used by these
other drivers. The scaling is 0–10V = 0–32767.
Put_PWM(PWM6,6553)
will generate 2.0 volts at the analog output. VCL can monitor this output using
the variable Analog_Output.
INTERFACING THE THROTTLE AND BRAKE COMMANDS
VCL can interface and modify the throttle and brake signals at several points, from
the potentiometer to the final motor controller command. VCL can be used to
create a completely unique command, adjust parameters to provide MultiMode,
or modify the throttle command based on steering angle, height, etc.
The throttle and brake signal chains within the controller are sophisti-
cated and flexible. Before applying VCL to modify these chains, it is important
to fully understand the ramifications of these changes. The motor command
diagram is presented in Figure 14.
Throttle Processing
The top of Figure 14 shows the throttle processing section. The throttle signal
chain flows left to right starting with the physical throttle pot. The voltage on
the throttle wiper input (pin 16) is input into the controller and has the VCL
variable name Throttle_Pot_Raw which is displayed in the 1311 Monitor
» Inputs
menu. This throttle signal is then modified by the Throttle Type Processing
and Throttle Mapping blocks.
The Throttle Type Processing block combines the Throttle_Type parameter
(see page 42) and the throttle potentiometer input (Throttle_Pot_Raw) to cre-
ate a 16-bit variable containing the magnitude of the raw command. This raw
command passes to the Throttle Mapping block, which re-shapes the throttle
signal magnitude and direction based on the various Throttle Menu parameters
(see pages 42–43) and the direction inputs.
Following the Throttle Mapping block are two switches whose purpose
is to give the throttle signal a small value (1 for the forward switch, and -1 for
the reverse switch) to indicate that a direction switch is On—but only if the
throttle signal output from the Throttle Mapping block = 0.
The signal then passes through a selector switch. If the Throttle_Type
parameter is set to 5 (Throttle Type = VCL input, see page 42), the Throttle
Mapping block output signal is ignored and the command comes from the
VCL variable VCL_Throttle. The VCL program manipulates the VCL_Throttle
variable to get a throttle command. When the Throttle Type is set to 1–4, the
variable VCL_Throttle does nothing, and the Throttle Mapping block output
signal passes through.
After the “Throttle Type = 5” switch, the throttle signal is modified by the
multiplying and summing nodes. These nodes can be adjusted by VCL through
the variables Throttle_Multiplier and Throttle_Offset. This is the basic input
point for creating functions like MultiMode, dual drive algorithms, and height
vs. speed control. Note that the throttle multiplier has a built-in “divide by 128.”