I am using PCI-6229 and trying to develop a code that can generate a TTL/square function signal as soon as one analog input satisfies following conditions: 1. Crossing a certain value (say, 0 V); 2. Falling edge slope. The time delay between the crossing point and newly generated TTL/square signal will be critical in my measurement, and it should not exceed 1 millisecond. Any suggestion on it? Thank you in advance!