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© Sealevel Systems, Inc. 7205e Manual | SL9239 12/2022
RS-422 & RS-485 (DB9 Male)
Pin #
Signal
Name
Mode
1
RX +
Receive Data Positive
Input
2
RX –
Receive Data Negative
Input
3
TX –
Transmit Data Negative
Output
4
TX +
Transmit Data Positive
Output
5
GND
Ground
6
RTS +
Request to Send Positive
Output
7
RTS –
Request to Send
Negative
Output
8
CTS – Clear to Send Negative
Input
9
CTS +
Clear to Send Positive
Input
Baud Rates and Oscillator Value
The 7205e utilizes a 14.7456MHz oscillator, which is automatically entered by the SeaCOM driver under
Windows 2000/XP/Vista operating systems. The oscillator value can be found in the COM port properties
of Device Manager under the ‘Advanced Tab’.
The high-speed oscillator and the UART’s flexible clock prescaler support a wide range of standard and
non-standard baud rates. You simply need to select the appropriate baud rate in your communications
software and the driver will calculate the closest matching baud rate.
When you use the board in other operating systems like Linux, the baud rate you select is multiplied by eight
resulting in the actual, faster baud rate. This allows the board to achieve data rates to 921.6K bps.
