.TH E1432_SET_TRIGGER_CHANNEL 3 E1432
.SH NAME
.nf
e1432_set_trigger_channel \- Enable a channel to generate triggers
e1432_get_trigger_channel \- Get current trigger setting
.fi
.IX e1432_set_trigger_channel(3) 3
.IX e1432_get_trigger_channel(3) 3
.SH SYNOPSIS
.cS
SHORTSIZ16 e1432_set_trigger_channel(E1432ID hw, SHORTSIZ16 ID,
                                     SHORTSIZ16 state)
SHORTSIZ16 e1432_get_trigger_channel(E1432ID hw, SHORTSIZ16 ID,
                                     SHORTSIZ16 *state)
.cE
.SH DESCRIPTION
\fIe1432_set_trigger_channel\fR sets a single channel or group of
channels, \fIID\fR, to digitally trigger a measurement, depending on
the value given in \fIstate\fR.

\fIe1432_get_trigger_channel\fR returns the current value of the
digital trigger source, of a single channel or group of channels
\fIID\fR, into a memory location pointed to by \fIstate\fR.

This parameter may also be set with \fIe1432_set_trigger\fR.

\fIhw\fR must be the result of a successful call to
\fIe1432_assign_channel_numbers\fR, and specifies the group of
hardware to talk to.

\fIID\fR is either the ID of a group of channels that was obtained with a
call to \fIe1432_create_channel_group\fR, or the ID of a single channel.

\fIstate\fR determines if the channel or group of channels can
digitally trigger a measurement.

\fBE1432_CHANNEL_OFF\fR disables it from triggering the measurement.

\fBE1432_CHANNEL_ON\fR enables it to trigger a measurement, and also
enables a trigger channel on an Option AYF tachometer board to pre-arm
the measurement if the pre-arm mode is \fBE1432_ARM_EXTERNAL\fR.

\fBE1432_CHANNEL_PRE_ARM\fR enables the channel to pre-arm a
measurement, but not trigger the measurement, and is valid only for
the trigger channel on an Option AYF tachometer board.

In addition to selecting a channel or group of channels as a source
for triggering a measurement, it is possible to set up the following
trigger parameters for each of the selected channels: the level may be
set with \fIe1432_set_trigger_level\fR, the slope may be set with
\fIe1432_set_trigger_slope\fR, and the mode may be set with
\fIe1432_set_trigger_mode\fR.

A channel or group of channel which has been set to digitally trigger
the measurement will implicitly do that on a local (i.e. module)
basis.  If it is required that these local trigger conditions
translate into system wide (i.e. multiple modules) conditions, it is
necessary to configure the module to act upon the system
sync/arm/trigger line (see \fIe1432_set_multi_sync\fR).  This is
normally handled automatically by \fIe1432_init_measure\fR.

Input channels can be set to trigger the system when the input signal
crosses a threshold, or when the input signal exceeds programmed
bounds.  Source channels can be set to trigger the system at the start
of a "burst".  Some tach channels can be set to trigger the system
when the signal crosses a threshold.

For the Option AYF tachometer, only the second of the two tach
channels can be set to trigger in the non-RPM arming modes; the first
tach channel is not capable of triggering.  In the RPM arming modes,
either channel can be used for RPM arming/triggering.  If the module's
pre-arm mode is set to \fBE1432_ARM_EXTERNAL\fR, then the second of
the two tach channels can be used to pre-arm the measurement.

.SH "RESET VALUE"
After a reset, \fIstate\fR is set to \fBE1432_CHANNEL_OFF\fR.
.SH "RETURN VALUE"
Return 0 if successful, a (negative) error number otherwise.
.SH "SEE ALSO"
.na
e1432_set_multi_sync, e1432_set_trigger, e1432_set_trigger_level,
e1432_set_trigger_mode, e1432_set_trigger_slope,
e1432_set_pre_arm_mode.
.ad
