Brake Processing - Curtis 1232E Manual

8 — VCL
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Brake Processing

Brake processing is optional as it can be turned Off (by setting Brake_Ped-
al_Enable = Off, see page 47). If turned On, brake processing can be done with
or without VCL. When the controller is in Speed Mode, any non-zero brake
command will then override the throttle signal and the motor controller will
brake to a stop as determined by the parameters Brake Current Limit (page 41)
and Brake Taper Speed (page 39). When the controller is in Torque Mode, the
brake command is multiplied by 2 and subtracted from the throttle command
to produce the final command; thus a 50% brake command will cancel a 100%
throttle command.
The lower part of Figure 15 shows the brake signal processing section. The
brake signal chain flows from left to right starting with the physical brake pot.
The voltage on the brake wiper input (pin 17) is input into the controller and
has the VCL variable name Pot2_Raw which is displayed in the programmer's
Monitor » Inputs menu. This brake signal is then modified by the Brake Type
Processing and Brake Mapping blocks.
The Brake Type Processing block uses the Brake_Type parameter (page 47)
and the brake potentiometer input (Pot2_Raw) to create a signed 16-bit variable.
This brake signal then passes to the Brake Mapping block, which re-shapes the
brake signal according to the various Brake Menu parameters (page 47).
The signal then passes through a selector switch. If the Brake_Type pa-
rameter is set to 5 (Brake Type = VCL input, see page 47), the Brake Mapping
block output signal is ignored and the command comes from the VCL variable
VCL_Brake. The VCL program manipulates the VCL_Brake variable to get a
brake command. Custom braking functions can be set up in this fashion; e.g.,
braking based on a switch position or an internal fault. The brake potentiometer
can still be used, but must be set up using the Setup_Pot() function. When the
Brake Type is set to 1–4, the variable VCL_Brake does nothing and the Brake
Mapping block output signal passes through.
After the "Brake Type = 5" switch, the brake signal passes through a
limiter which limits the brake signal to a range of 0–100% (0–32767). After
the limiter the brake signal is a VCL variable called Mapped_Brake, which is
displayed in the Monitor » Inputs menu. Checking the value of Mapped_Brake
is a good way to see if your Brake Menu parameters are set correctly. A VCL
program can control the brake by changing the variable VCL_Brake (only if
Brake Type = 5).
The brake signal then goes through a second selector switch that will set
the brake signal = 0% if the Brake Pedal Enable parameter (page 47) is set Off.
If set On then the brake signal will pass through. The brake signal after this
second selector switch is a VCL variable called Brake_Command, which is
displayed in the 1313/1314 programmer's Monitor » Inputs menu.
Brake_Command is the final value of the brake signal chain that is input
to the Control Mode Processing block; see Figure 16. If Brake_Command is
non-zero in Speed Mode Express or Speed Mode, the throttle signal will be
set to 0%.
Curtis 1232E/34E/36E/38E & 1232SE/34SE/36SE Manual,
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