I was asked to summarize the SWWD (software watchdog) timing sequence as a reminder.

t=0: SUS IOP detects top OSEM RMS exceeds trip level, starts its 1st countdown (5 mins)

t=5mins: SUS IOP 1st countdown expired, its IPC output goes to BAD and it starts its 2nd countdown (15 mins). SEI IOP receives the BAD IPC, and starts its 1st countdown (4 mins)

t=9mins: SEI IOP 1st countdown expired, its IPC output goes to BAD and it starts its 60 second 2nd countdown. SEI user models get the 60 second warning IPC so they can cleanly shutdown before the DACs are killed

t=10mins: SEI IOP 2nd countdown expired, DAC cards associated with the chamber the SUS is located in are killed

t=20mins: SUS IOP 2nd countdown expired, SUS DAC cards are killed

For the hardware watchdog (HWWD) the times are doubled. The power to the ISI Coil Driver chassis is removed after 20 mins of continuous SUS shaking.