th_in_gs, 1 year ago I suspect your serial converter is expecting a ‘real’ RS232 signal, with its old-school now-weird voltage levels. Your USB serial adapter is probably using 5V or 3V so-called ‘TTL’ signaling (which in the real world is mostly cross-compatible between 5V and 3V) Good explanation here: https://www.sparkfun.com/tutorials/215
I suspect your serial converter is expecting a ‘real’ RS232 signal, with its old-school now-weird voltage levels.
Your USB serial adapter is probably using 5V or 3V so-called ‘TTL’ signaling (which in the real world is mostly cross-compatible between 5V and 3V)
Good explanation here: https://www.sparkfun.com/tutorials/215