I can't receive data from Com Port

1
votes

I connect com3 to com4 from my pc to another pc using Prolific USB-to-Serial Comm Port on both sides (using Rs232 female between both). I can send data to port from both computer successfully.

But I can't receive any data on both sides.

Ports config on both sides is the same.

When I monitor this connection, I see status of CTS,DSR,DCD,RI is Disable(Red) (just RTS,DTR is Enable(Green)).

I using "null modem" and tested cable. Do you have a solution for receiving data?

1
serial-port
Typo alert - it's spelled receive - not "recieve" .... – marc_s
CTS and DSR must never be off with a proper null modem cable. Since CTS connects to RTS on the other side and you know that RTS is on. Same for DTR and DSR. You can fumble along by setting the Handshake property to None, a property that must always be assigned. – Hans Passant
how can i change to set on DTS and DSR? i use Serial Port Monitor 7 for test Connection. – Pedram-Faraji

1 Answers

1
votes

You need to cross Rx/Tx signal lines, or use a "null modem" cable. The latter does not only cross the data lines (pins 2 and 3 on DB9 connector), but also the corresponding flow control signals.

A simpler test would connect pins 2 and 3 on a DB9 RS232 port, and use a terminal program with "local echo" set to off. This setup just receives anything you send out - veifying that the USB2UART adapter actually works.