J. Kissel, for D. Barker

Here is be the timing sequence (assuming the excitation of the suspension is continuous) implemented on H1 SUS/SEI ETMY IOP Software Watchdog (SWWD) and Hardware Watchdog (HWWD):

1. T=0, SUS detects an excitation of the suspension, starts its IOP SWWD WD countdown timer. HWWD also starts its countdown.

2. T=5 mins, the SUS WD countdown expires. The IPC to the SEI IOP SWWD goes to zero.
2.1 the SEI SWWD WD countdown timer starts
2.2 the SUS SWWD DK countdown timer starts

3.0 T=9mins, the ISI and HEPI models see only one minute left on the SEI IOP WD countdown, nicely zero out the DAC drives in preparation for DACKILL

4.0 T=10mins, the SEI IOP SWWD times out and DAC KILLS the ISI and HEPI DACS

5.0 T=20mins, the SUS IOP SWWD times out and DAC KILLS the SUS DACS. Also the HWWD powers down the ISI coil driver chassis and HEPI valve driver chassis

6.0 T=40mins the HWWD opens the relay contacts disabling the SUS coil drive signals.