Matrox Meteor-II /Digital Installation And Hardware Reference page 41

40 Chapter 5: Hardware reference
Clock
Auxiliary I/Os
Exposure
Trigger
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The interface of the Matrox Meteor-II /Digital board can receive
and supply a clock, simultaneously.
Seven general purpose auxiliary signals are supported on the
PCI form factor: four RS-422 or LVDS user signals (two input,
two output), and three TTL output signals. The PC/104-Plus
form factor supports six auxilliary signals: four RS-422 or LVDS
user signals (two input, two output), and two TTL output
signals. These are available for controlling external devices,
such as a strobe light. User signals are programmed using the
MIL-Lite command MdigControl().
Two timers in the PSG can generate two exposure signals
simultaneously. These are available in TTL or RS-422/LVDS
formats. Exposures are programmed using the MIL-Lite
function, MdigControl().
Three trigger inputs are routed directly to the PSG; the
interface supports TTL , RS-422/LVDS, and opto-isolated
trigger inputs. The latter, connected to the OPTOTRIG- and
OPTOTRIG+ input pins, passes through an opto-coupler, a
device that protects the board from outside surges; OPTOTRIG-
is usually connected to the ground of the trigger source.
External trigger inputs allow image acquisition to be
synchronized with external events. The board can operate in
one of two modes, and the selected mode is specified by the DCF.
Matrox Meteor-II /Digital can operate in next valid frame/field
mode. When in this mode, the digitizer waits for the next valid
frame or field (as specified by the DCF file) before commencing
the grab. This trigger mode functions in one of three ways:
Edge-triggered monoshot acquisition: The VIA (Video
■
Interface Asic) waits for the rising/falling edge to capture a
single frame.
Edge-triggered continuous acquisition: The VIA waits
■
for the rising/falling edge to start a continous grab.
Level-sensitive "continuous" acquisition: The VIA grabs
■
continuously while the level of the trigger is high/low.