On Tue, 5 Nov 2019 10:36:58 -0800 (PST), three_jeeps
wrote:

On Tuesday, November 5, 2019 at 8:14:42 AM UTC-5, legg wrote:
I've got a battery management unit that is reluctant to
demonstrate functionality. The vendor's terminal com
software seems non-functional (will not install).

So far the only evidence of life is a control line (one
of three) hard on, and rare /XFFE /FFF signalled outputs
on the rs232 port. Internal DC-DC fails to power LEM
sensor. Balancing terminals seem inactive.

Can anyone recommend a tutorial on poking a serial port
for status / data register contents ?

It should be reporting on the voltage of four LiFePO4 batteries,
powering a LEM sensor and reporting current. Many other
undocumented features for I/O via remote terminal. Has
CAN port, which seems to be used only for control power and
crude 'run' (input) /'stop charging' (output) LF/DC signals.

snip
RL
What initially comes to mind is to connect a terminal or terminal emulator
and try some of the more run of the mill key sequences: return (return n
times), ctl-c, ctl-d, esc, F1..Fn, etc.
What comes back may not be visible on a terminal unless the terminal can
display non-printing ASCII characters. A serial line logic analyzer in
parallel may help.
snip

Monitoring program is MicroRidge Comtest Serial.
Can issue single characters, or a string.

Return - you mean CR /x0d ?

Cntrl - ? how to?

RL