50 lines
1.9 KiB
Groff
50 lines
1.9 KiB
Groff
.TH WATCHDOG "9" "2010-06-22" "LinuxCNC Documentation" "HAL Component"
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.SH NAME
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watchdog \- monitor multiple inputs for a "heartbeat"
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.SH SYNOPSIS
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.HP
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.B loadrt watchdog num_inputs=\fIN\fR
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.P
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You must specify the number of inputs, from 1 to 32. Each input has a
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separate timeout value.
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.SH FUNCTIONS
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.TP
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\fBprocess\fR
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Check all input pins for transitions, clear the \fBok\-out\fR pin if any
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input has no transition within its timeout period. This function does not
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use floating point, and should be added to a fast thread.
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.TP
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\fBset\-timeouts\fR
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Check for timeout changes, and convert the float timeout inputs to int
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values that can be used in \fBprocess\fR. This function also monitors
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\fBenable\-in\fR for false to true transitions, and re-enables monitoring
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when such a transition is detected. This function does use floating point,
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and it is appropriate to add it to the servo thread.
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.SH PINS
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.TP
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.B watchdog.input\-n\fR bit in\fR
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Input number n. The inputs are numbered from 0 to \fBnum_inputs\fR\-1.
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.TP
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.B watchdog.enable\-in\fR bit in \fR(default: \fIFALSE\fR)
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If TRUE, forces out\-ok to be false. Additionally, if a timeout occurs on
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any input, this pin must be set FALSE and TRUE again to re-start the
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monitoring of input pins.
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.TP
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.B watchdog.ok\-out\fR bit out \fR(default: \fIFALSE\fR)
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OK output. This pin is true only if enable\-in is TRUE and no timeout has
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been detected. This output can be connected to the enable input of a
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\fBcharge_pump\fR or \fBstepgen\fR (in v mode), to provide a heartbeat signal
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to external monitoring hardware.
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.SH PARAMETERS
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.TP
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.B
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.B watchdog.timeout\-n\fR float in\fR
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Timeout value for input number n. The inputs are numbered from 0 to
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\fBnum_inputs\fR\-1. The timeout is in seconds, and may not be below zero.
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Note that a timeout of 0.0 will likely prevent \fBok\-out\fR from ever becoming
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true. Also note that excessively long timeouts are relatively useless for
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monitoring purposes.
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.SH LICENSE
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GPL
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