Serial debugging several understanding

RS-232C interface definition (DB9)
Pin defined symbol
a carrier detect the DCD (the Data Carrier Detect)
2 receives the data the RXD (Received the Data)
. 3 transmits data the TXD (Transmit the Data)
. 4 Data Terminal Ready the DTR (the Data Terminal the Ready)
. 5 signal the SG (Signal ground)
. 6 data ready the DSR (the data the Set the ready)
. 7 request to send the RTS (the to the send the request)
. 8 Clear to send the CTS (the to the Clear the send)
. 9-rings RI (Ring Indicator)
the serial port with the development labcvi when writing a program with multi-function serial port debugging assistant virtual com port com1 and com2 communication, I found that every time labCVI occupied com1 mouth, then another software only with the com2 port (the reason may be labcvi been in debug state, did not really quit due).