The power switch is what is usually refered to as a soft key. It isn't a physical power contact. Depends on how much is turned off with that soft key. I imagine most of the radio, but having a remote soft key probably could have been done, just not with the current design.
If the power is off then how can ProScan communicate with the scanner to tell it to turn on?
I understand, BUT how about a power OFF button?
I'm pretty sure there is not a protocol command to do that.
The power is not truly off. That button is a soft button. Power is still applied to some circuits of the radio, at least enough to recognize pressing the ON button. A more accurate description is that it is asleep or in standby. Almost all modern electronics work this way. TVs, DVRs, DVD/Blueray players. Cell phones! Computers have a not so often used feature known as Wake-On-Lan. When you turn off your computer, it is in reality in a standby mode if power is still applied. If Wake-On-Lan is enabled and used, you can "turn on" a computer by sending a command to it over the network it is connected to.
The closest you can get now with ProScan is to send the MSM command without a timeout specified. That will put the scanner in Mass Storage mode indefinitely I believe.
It may not be truly off but the the serial interface does not work .
Understand. But the serial interface could have been made to wake up when a signal was sent to it just as is done with Wake-On-Lan. There are apparently some UARTs that will wake up when a signal is sent to them.
Agree, but only goes to a simple switching circuit. I'm pretty sure that there's no power applied to the CPU circuits in Unidens handheld scanners. When scanner are running, the CPU signals to a power switching transistor or IC to keep the power on. When you signal to the CPU from the on/off button to switch off, the CPU it will do a controlled shutdown with a save to SD card, if it uses one, and then the CPU cut the signal to the switching transistor/IC that then cuts all power.
I am at a disadvantage not having a schematic for the SDS 100. I have the schematic for the UBC125XLT and looked for the power on circuit. . It works the same way. Q304 switches the power when the power button is pressed. A UART with a wakeup function could just as well activate the power, but of course all this would require a design change to incorporate the function. It would be a neat feature. Also, it would be possible to add external circuits to do the same thing, but you would have to extend the power button contacts out of the scanner with wiring to a device that detected serial data received at the USB port and processed a command. Sounds like a project for the ARDUINO experimenters.
I can just imagine running the scanner remotely. "Oops I hit the power off button, now what do I do?"
This, along with an IP based switch would accomplish what the OP wants. Go into MSM, wait a period of time, then trigger the IP switch. To turn it back on, trigger the IP switch.
Arduino are great little things that would easily fit in the scanner and I think they can be programmed by anyone who understands logik, if X-then do this- else do that. I believe it has some sort of power save/sleep mode where it doesn't use much power. Let it sense the RX data pin on the USB connector to wake up from sleep and then activate the on/off circuitry. It could even sense when RX data have been gone for a few minutes and simulate a long push on the on/off to power off the scanner, if needed when communication are lost, or sense a whole data telegram that where sent to be used as power off, perhaps the Att Off command which doesn't matter to the scanner.
