6 ms·

"Soft Bypass function The Soft Bypass function allows me to over-ride the status of the hardware bypass switch when needed. When Soft Bypass is engaged, the byp

"Soft Bypass function The Soft Bypass function allows me to over-ride the status of the hardware bypass switch when needed. When Soft Bypass is engaged, the bypass button's LED flashes to remind me Soft Bypass mode is enabled." These sort of things usually end in tragedy. I worked at a chemical plant that had an explosion where the safety systems (SIS) were bypassed. The engineers were trying to light off a boiler and were having trouble. The safety system had a 30 minute time delay between unsuccessful light off attempts to allow the fuel to disperse. The engineers bypassed the time delay and attempted multiple unsuccessful light offs in a row which flooded the boiler with fuel. Finally, it lit and went boom. Those near the equipment in the field were all killed. Hope you don't have any pets, children, or slow moving adults around.

jrockway 5y ago
The "bypass" system seems to only suppress notifications about the door being open. This project doesn't appear to be coupled to any garage door control systems; it can't open or close the door, it can only report on the current state by ringing the doorbell or sending email. It seems that even if the system grossly malfunctions, you're left with a perfectly normal garage door opener. So the lecture about safety is probably not applicable here -- more likely is that the thing catches on fire, or gets the Google account banned after ignoring some rate limit.
- simondotau 5y ago
  I added automation to my garage door, but not before calibrating (and carefully testing) the force limits on the motor, and installing (and carefully testing) an infrared trip sensor which integrates into the motor. When a garage door doesn't close when requested (or does open when not requested) it will spray notifications to everyone's phone, but it won't try to close the door again.
froh 5y ago
yes, naming is hard. the gadget is not a garage door control but purely a mgarage door monitor. so the so called bypass is purely related to the monitor. the garage door control, if any, with its safety features remains completely stand alone. that to me looks like an ok architecture from the safety pov, where the gadget behaves as an eye and maybe a finger pushing the control remote, so the safety is delegated to the garage control. to state the obvious, I'm fully with you that there should be no override bypass inactive whatever on any kind of safety sensor, and the sensor should always be fail safe, i.e. if a sensor fails the motor stops, if an electronics compinent fails, the motor stops, if not locked shut it should be possible to manually completely reopen the door, etc. obligatory pointer to Nancy Leveson http://sunnyday.mit.edu/ http://sunnyday.mit.edu/
t0mas88 5y ago
You have this exact same thing with airplane engine starts. Add fuel at the wrong time and the whole thing either exceeds temperature limits and has to be completely taken apart or you cause a fire. The most common cause of destroyed engines is exactly like you describe for the boiler, it didn't start the first time and someone ignores the cooldown limits and/or cause of the failed start (e.g. not enough power in the batteries to get the turbine up to minimum speed before adding fuel, try again now with even less power because you used some on the first attempt)
djrogers 5y ago
> These sort of things usually end in tragedy. > Hope you don't have any pets, children, or slow moving adults around. What aspect of a garage door status monitor do you consider a safety item? This has nothing to do with the various safety systems built in to garage doors (IR sensors, pressure sensors, etc) - it just alerts the owner if they forgot to close the garage door. The bypass silences those reminders.

jrockway 5y ago

The "bypass" system seems to only suppress notifications about the door being open. This project doesn't appear to be coupled to any garage door control systems; it can't open or close the door, it can only report on the current state by ringing the doorbell or sending email. It seems that even if the system grossly malfunctions, you're left with a perfectly normal garage door opener. So the lecture about safety is probably not applicable here -- more likely is that the thing catches on fire, or gets the Google account banned after ignoring some rate limit.

simondotau 5y ago
I added automation to my garage door, but not before calibrating (and carefully testing) the force limits on the motor, and installing (and carefully testing) an infrared trip sensor which integrates into the motor. When a garage door doesn't close when requested (or does open when not requested) it will spray notifications to everyone's phone, but it won't try to close the door again.

froh 5y ago

yes, naming is hard. the gadget is not a garage door control but purely a mgarage door monitor. so the so called bypass is purely related to the monitor. the garage door control, if any, with its safety features remains completely stand alone. that to me looks like an ok architecture from the safety pov, where the gadget behaves as an eye and maybe a finger pushing the control remote, so the safety is delegated to the garage control. to state the obvious, I'm fully with you that there should be no override bypass inactive whatever on any kind of safety sensor, and the sensor should always be fail safe, i.e. if a sensor fails the motor stops, if an electronics compinent fails, the motor stops, if not locked shut it should be possible to manually completely reopen the door, etc. obligatory pointer to Nancy Leveson http://sunnyday.mit.edu/ http://sunnyday.mit.edu/

t0mas88 5y ago

You have this exact same thing with airplane engine starts. Add fuel at the wrong time and the whole thing either exceeds temperature limits and has to be completely taken apart or you cause a fire. The most common cause of destroyed engines is exactly like you describe for the boiler, it didn't start the first time and someone ignores the cooldown limits and/or cause of the failed start (e.g. not enough power in the batteries to get the turbine up to minimum speed before adding fuel, try again now with even less power because you used some on the first attempt)

djrogers 5y ago

> These sort of things usually end in tragedy. > Hope you don't have any pets, children, or slow moving adults around. What aspect of a garage door status monitor do you consider a safety item? This has nothing to do with the various safety systems built in to garage doors (IR sensors, pressure sensors, etc) - it just alerts the owner if they forgot to close the garage door. The bypass silences those reminders.