This connector is not as common as the DE-9 connector. These connections can be seen in blue below (figure 2 for RS-232 and figure 3 for RS-422/485).įigure 2: RS-232 female DE-9 plug with connections required for loopback testįigure 3: RS-422/485 female DE-9 plug with connections required for loopback test Both of these connections are required for RTS/CTS hardware flow control since RS-422/485 have differential connections. For RS-422/485, you will need to connect pins 2 to 3 and 6 to 7. Pins 7 and 8 are used for RTS/CTS hardware flow control where pins 4 and 6 are used for DTR/DSR hardware flow control. When using hardware flow control, you will need to connect pins 4 to 6 and 7 to 8 for RS-232. These connections can be seen in redbelow (figure 2 for RS-232 and figure 3 for RS-422/485). To perform a loopback test with no hardware flow control, you will need to connect pins 2 and 3 for RS-232 and pins 4 to 8 and 5 to 9 for RS-422/485. This connector is found on National Instrument’s one and two port serial interfaces.įigure 1: Pinout diagram for DE-9 Connector The DE-9 connector is the most common serial connector.
