Serial Port Pulse

Is it possible to pulse one of the pins on the serial port of a 433 board. I found at least one post on the subject which mentioned to try:
/ port set serial0 dtr=on rts=off
I’ve tried that as well as switching dtr=on to dtr=off with a script, but it is not clear as to whether the RB433 supports dtr=

It looks like pin3 is -5V when idle as stated in the RB433 user guide. Any command I can use to get it to +5V?

Thanks,