mcudogs wrote: Or you could use this freeware serial port monitor software.
Thanks for that, Don! It's pretty close to what I was looking for. I'm pretty impressed that its tentacles can reach out of the computer to the serial hardware that is out past the USB port. But of course it just looks at the serial API, and it all "just works". Impressive.
It still has some Windows limitations showing through. For example, I wrote a program to just send commands to the BMUs; I can see the commands going out. But I can't see the reply, apparently because "no-one is listening". I can't run HyperTerminal to read the result, because my program already has the serial port opened. Sigh. I need "half a comms program" or a program that "opens half the serial port".
There may be other options in the serial port monitor to explore. I guess I'll have the same problem with the charger; nothing will be "listening to what the charger is saying".
The other issue that I had is that it wanted me to "close the application" that has holding the serial port. Well, I did; it has an infinite loop, and I used ^C to cancel out of it. Of course, that means that I bypassed the code that closed the serial port. So the monitor program was hanging (at 100% CPU no less) waiting for the comms port to get closed, and it wasn't going to happen. I had to wind the Windows down and up again to fix that one; process monitor would not kill the monitor (presumably because it has to do some tricky driver-level things that Windows doesn't like to kill).