Irq pin issue in SEN0542 fingerprint sensor(UART)

Hi, i was understanding working of sensor SEN0542(uart capacitive fingerprint sensor) by executing sample codes, and i came across the IRQ pin in sensor module.

i checked if there is any pulse(toggling) on IRQ pin on finger touch using logic analyzer, but i dont see any pulse on irq pin output.

Is There any software configuration to be done for using IRQ pin? or does it need hardware external  pull up? . Please let me know if am missing something and how to use IRQ pin.