Polarity combination: Configure four modes through registers -0 (input falling edge+output low validity), 1 (input falling edge+output high validity), 2 (input rising edge+output low validity), and 3 (input rising edge+output high validity).
3.2 Busy Timer Protection
To prevent multiple trigger signals from interfering with each other, FIW64 has a built-in "trigger busy flag". When a valid trigger input is detected, the busy flag is set and a timer is started (T4=T3+0.1ms). During this timer counting period, any new trigger inputs will be ignored. This mechanism ensures that each trigger outputs complete execution, avoiding overlapping or truncation of output pulses. Users can query the triggering status through software (if supported by the driver), or design external logic based on the timing diagram.
3.3 Typical application scenarios
Strobe lighting synchronization: The camera exposure signal is used as the trigger input, and after a delay of T2, the trigger signal is output to light up the LED flash, achieving precise fill light.
Multi camera time-division capture: Using different trigger channels to set different delays, multiple cameras can be sequentially exposed to avoid light source conflicts.
Motion triggered positioning: After the photoelectric sensor detects that the workpiece is in place, the trigger input is delayed, and the output signal triggers the camera to capture, which is synchronized with the encoder to achieve position synchronization.
When programming, it is necessary to call FIW64_SetTriggerDelayTime (set delay), FIW64_SetTriggerWidth (set pulse width), and FIW64_SetTriggerPolarity (set polarity), and read the current configuration through functions such as FIW64_SetTriggerDelayTime for debugging.
Guidelines for Connecting Input/Output Circuits to External Devices
4.1 Digital Input/Trigger Input Connection
Switch input: Connect one end of an external switch (such as a photoelectric sensor output) to the input pin (such as Digital Input 1) and the other end to the corresponding common terminal (Digital Input Common 1). Note that the common terminal can be connected to an external power source or ground, depending on the sensor type (NPN/PNP). The card optocoupler provides electrical isolation for the input, avoiding ground loops.
TTL signal input: When an external device outputs TTL level (0-5V), the TTL ground wire needs to be connected to the system GND, but attention should be paid to the signal polarity: due to the polarity of the LED inside the optocoupler, if the external signal is highly effective, it may need to be logically reversed in the software (such as through an inverter circuit or driver layer configuration). The manual suggests using a reverse connection method (such as connecting the TTL signal to the common terminal and the common terminal to the input pin) to obtain in-phase response. Please refer to Figure 2-9 for details.
4.2 Digital Output/Trigger Output Connection
Drive relay or indicator light: The output pin is in the form of current injection, that is, when the output is logic high (set by software 1), the internal transistor conducts, and the current flows from the external load (connected to the positive power supply) into the output pin, and then flows through the transistor to the common terminal (COM). The load power supply (3~24V) needs to be provided externally, and the load current should not exceed 80mA (digital output) or 40mA (trigger output).
Logic level output: If TTL high/low level needs to be output, an external pull-up resistor needs to be connected to+5V, and the logic level is generated by the on/off of the output transistor. The manual example provides the connection method, where the output high level (transistor off) is obtained by pulling up the resistor, and the output low level (transistor on) is low.
4.3 Loop Test
To verify the integrity of the trigger link, the trigger output signal can be physically connected to the trigger input (the same card or another card), and the trigger pulse can be sent through software to read the input status, achieving self checking. This is very useful during the system debugging phase.

Hardware installation and driver deployment
5.1 Physical installation steps
Turn off the host power, open the chassis, and select a PCIe slot that meets the bandwidth requirements (FIW62 can be plugged in x1, FIW64 requires x4 or above).
Remove the baffle, align the board with the slot, apply even pressure, and secure it with screws.
Connect the 1394b camera cable (it is recommended to use an industrial grade cable with a locking screw). If power is required for the camera, connect the 4-pin ATX power cord to CN5.
Cover the computer case and turn it on.
5.2 Windows System Driver Installation
After system startup, the built-in OHCI IEEE 1394 driver in Windows automatically recognizes and installs the basic 1394 bus driver (displayed as "Texas Instruments OHCI Compliant IEEE 1394 Host Controller" in Device Manager). If a yellow exclamation mark appears, you need to manually update the driver by pointing to the system's built-in driver or Windows Update.