Great!!! Success! Now, some notes...
zeno: It was the "Enable remote" that made it work. Thanks!
fbonomi: You seem to describe correctly what my camera does.
Jucifer: You also are correct. I missed the subtle difference of what you wrote at first. The difference being
With get_usb_power(1), the function reports ONLY 0 or 1; with get_usb_power(), the function reports ONLY 0 or the amount of time. And with get_usb_power(1), it updates when the level of the usb power changes whereas with get_usb_power(), it updates only when usb power goes low after having gone high.
I'm trying to clarify what I see here for other newbys like myself who may get here by searching the forum. So for a user who wants to know when usb power is applied, they should use get_usb_power(1). For someone who wants to know what the pulsewidth is, they should use get_usb_power().
On my SD1100, the command sequence to enable the remote is:
1. turn on camera
2. get in alt mode
3. press "Menu"
4. select "Miscellaneous stuff"
5. select "Remote parameters"
6. choose "Enable Remote"
7. Power off/back on: this item still selected. (I'm never sure which things get remembered and which don't after a power cycle.)
Having only the SD1100, I don't know what works on other models.
Although I searched most of the day yesterday for this information, I never found it. Does anyone know where these details are explained?
Thanks again to everyone for your help!!