Page last reviewed: 12:47:06 (Version: 8. The main purpose of this null modem cable is to let well defined software think there is handshaking available, with a null modem cable which has no provisions for it.Īll specified RS232 signals are completely isolated from the 'computer earth' and the 'mains supply'.įrom the transmission parameters, only the baud rate can be selected from 1200 up to 9600. The null modem cable with loop back handshaking resulted from this. To overcome this problem and still be able to use a cheap null modem communication cable with only three lines in it, a fake null modem cable layout has been defined. with this null modem cable, good written programs will perform worse than badly written programs.

The main problem with this cable is that there is a possibility for the software to hang if it checks the modem signal lines in a proper way. The simple null modem cable without handshaking shows incompatibilities with common software. Null modem with loop back handshaking for DB 9 connectors Set when incoming ring detected - used for auto-answer application. Related Range BL - Bluetooth Serial Adapter CC - PCI Serial Cards ES - Ethernet to Serial PM - Serial PC Card (PCMCIA) PX - PCI Express Serial Cards UC. 3V) For example, Advanced Serial Port Monitor can automatically control the DTR signal and set it LOW (-12V) when sends data out. Raised by DCE in response to RTS from DTE RS232 uses following voltages for signals: Signal 0 (LOW) > +3.0V (+3V. In auto-answer mode raised only when RI arrives from DCEĭata Set Ready.

Arriving data from DCE.ĭata Terminal Ready. The 9-pins sub D (male) connector is for the serial output of the Starrsed Compact.ĭB9: View looking into female connector DCEĭB9: View looking into male connector DTEĪt the female connector the pin layout is:ĭata Carrier Detect.

Appendix - RS-232 (DB9 pins male) hardware back panel connector

Db9 female serial port pinout diagram