User's Manual

905U-K.MAN Rev. 1.1 January 2002
 ELPRO Technologies Pty Ltd Page 27
Pin Name Dirn Function
1 - - Not Used.
2 RD Out Receive Data - Serial Data Output (High = 0, Low = 1)
3 TD In Transmit Data - Serial Data Input (High = 0, Low = 1)
4 DTR In Data Terminal Ready - used by 905U-K as a "wake-up" signal
5 SG - Signal Ground
6 - - Not Used.
7 - - Not Used.
8 - - Not Used.
9 - - Not Used.
The DTR signal must be connected to the 905U-K to enable communications and “wake up” the
microprocessor. This means that the DTR wire must be connected - the PC does not need to
control DTR. When communications is established, the green LED will light continuously.
The serial port communicates at a baud rate of 9600 baud, 8 bits, no parity, one stop bit.
An example cable drawing for connection to a personal computer is detailed below:
E505 DB9 (M) Connector Computer DB9 (F) Connector
1 1 Not Used - optional
2 2 Receive Data
3 3 Transmit Data
4 4 DTR
5 5 Signal Ground
6 6 Not Used - optional
7 7 Not Used - optional
8 8 Not Used - optional
9 9 Not Used - optional