Specifications

Curtis 1310 Manual, Rev. B
41
1 6 F E B R U A R Y 2 0 0 8 D R A F T
5 — VCL
Digital Outputs
All 16 outputs on the 1310 are Pulse Width Modulated active low FET drivers.
They are not simply turned On or Off but must be set to a duty cycle between
0% and 100%. Setting the PWM value to 0 will turn the output off completely
(open output) while a setting of 32767 will set it completely on (always pulled
to B-). A setting of 16383 provides nearly 50% duty cycle. The Put_PWM
and Automate_PWM functions are used for all digital outputs. The variable
PWM#_Output (where # is 1 through 16) can be used by VCL to read the
present state of any output driver.
Each output also has an associated input. This input goes on and off with
the PWM and senses the actual state of the FET driver and wiring. Using the
input function on an output can allow the wiring of a circuit to be fault checked.
Using the wiring configuration shown in Fig. 3, the Aux Contactor on Output 2
can be checked for proper connection before and after engaging it.
If (PWM2_Output = 0) ;check if Aux Contactor is open (off)
{
If (SW_2 = ON) ; check if the input is high
{
;the PWM is off and B+ is getting to the pin,
;so the coil must be connected
Put_PWM(PWM2, 32767) ;close the Aux Contactor
}
Else ;there is a fault!
{
;the input sense was low, so the coil
;must be disconnected or open.
;put your fault detect code HERE....
}
}
If (PWM2_Output = 32767)
;check if the Aux Contactor is closed (on)
{
If (SW_2 = ON)
;the input should be low, check if it is high
{
;the PWM is full on but B+ is getting to the pin,
;so the driver is bad
;put your bad FET driver code HERE
}
}
Because in this example the Aux Contactor is on Output 2, the VCL code can
check that the coil, once turned on, draws a reasonable current. If you look
at Table 2 on page 7, you will see that the raw value of this current reading
is put into ADC16_Output. The next example extends the fault checking to
include this feature.