I made a python script for finding IR resonance using ALS. It currently lives in /opt/rtcds/caltech/c1/scripts/ALS/findIRresonance.py.

The basic algorism is as follows.

1. Scan the arm by putting an offset to the phase output of the phase tracker(Step C1:ALS-BEAT(X|Y)_FINE_OFFSET_OFFSET by 10 deg with 3 sec ramp time).

2. Fetch TR(X|Y) and OFFSET online data using pyNDS during the step.

3. If it finds a tall peak, sets OFFSET to the value where the tall peak was found.

4. If tall peak wasn't found, go back to 1 and step OFFSET again.

The time series data of how he did is plotted below.
I ran the script for Y arm, but it is compatible for both X and Y arm.