Appendix A - Red/Green Flash Script Start - Usl LSS-100P Installation And Operation Manual

LSS−100P Installation & Operation Manual
Appendix A – Red/Green Flash Script Start
LSS-100P installation is simplified by using a red and green flash sequence to start script execution. The
flash sequence avoids the need to add a cue (send TCP string or provide contact closure) to start a script.
The LSS-100P compares the output of the red and green sensors. When the green to red ratio exceeds a
threshold, the image is considered a binary 1. When the red to green ratio exceeds a threshold, the
image is considered a binary 0. A single ASCII character is sent using a sequence of red and green
images. The character is sent at 0.5 bits per second (2 seconds per bit). The character consists of a start
bit (0), 8 data bits with the least significant bit sent first, then one stop bits (1). The most significant bit is
0. The script starts on the 0 to 1 transition between the most significant bit and the stop bit. Because of
this, the script starts two seconds (one bit time) before the end of the clip. This two second difference
needs to be taken into consideration when writing scripts. Bits are sampled in the middle of the bit time
(based on the 1 to 0 transition of the beginning of the start bit). The letter 'A' starts script 0 (the first
one).
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