Matrox Meteor-II, Руководство по установке и аппаратным средствам

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34 Chapter 4: Hardware reference
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The polarity of the active and inactive levels of the trigger signal is software
programmable.
Matrox Meteor-II /Multi-Channel can also operate in asynchronous reset mode.
In this mode, the digitizer resets the camera to begin a new frame when the trigger
signal is received.
Direct TTL trigger
Trigger signals can be received in TTL format directly through the video-input
connector. The TTL level signal must have a maximum amplitude of 5 V. A signal
over 2 V is considered high while anything less than 0.8 V is considered low. The
transition of 0.8 V to 2 V is considered to be the rising edge.
The trigger signal’s pulse width must be greater than one pixel. You can determine
the pulse width by taking the inverse of the
pixel frequency . For example, if the
pixel frequency is 12.27 MHz, the minimum pulse width is 1/12.27 MHz
≈
82
nanoseconds.
Opto-isolated trigger
Trigger signals connected to the OPTOTRIG- and O input pins, pass
through an opto-coupler, a device that protects the board from outside surges;
OPTOTRIG- is usually connected to the ground of the trigger source. The voltage
difference across O and OPTOTRIG- must be between 4.05 V and
9.16 V for logic high, and between -5.0 V and 0.8 V for logic low. Refer to
Appendix B for the pinouts of these signals on your board.
UART
Matrox Meteor-II /Multi-Channel features a Universal Asynchronous
Receiver/Transmitter (UART) that provides an RS-232 serial interface. For
example, this allows you to remotely control a camera or a motion control unit,
or communicate with a program logic controller (PLC). The UART is
programmed using the MIL-Lite command
MdigControl() with the
M_UART...
control types.
Note that the UART is not present on the Meteor-II /Multi-Channel for
PC/104
-Plus .