The CT2 counter timer module is for counting all sources of TTL pulses including all ET Enterprises TTL photon-counting module and TTL amplifier discriminators. View outline drawing. 100 MHz capability 32 bit count capability integral microcontroller and RS232 interface to the host computer trigger input for synchronous counting operation The following operating modes are available with the software application provided: continuous readings fixed number of readings continuous readings with trigger high fixed number of readings - start on falling edge of trigger