Datasheet

- 17 -
DCE / DTE Connection Table
Because of the polarity of the communication signals, a DTE
configured device must connect to a DCE configured device. The
shaded area in the figure below is an example of a DTE to DCE
connection:
Self Test
To test the internal circuit of the interface converter, connect a
dumb terminal to the unit and do the following:
1. Set SW1 to DCE (if the dumb terminal is configured for DCE).
2. Set SW2 to TxON, RxON.
3. Connect a wire from pin 1 (Tx+) to pin 4 (Rx+)
4. Connect a wire from pin 2 (Tx-) to pin 3 (Rx-)
5. Set the terminal to full duplex and enter data.
If the data displays on the screen, the internal circuit is
operational.
DCE
DB-9
2
3
8
7
4
6
5
DTE
DB-9
3
2
7
8
6
4
5
DCE
DB-25
3
2
5
4
20
6
7
DTE
DB-25
2
3
4
5
6
20
7
DCE
DB-25
2
3
4
5
6
20
7
DTE
DB-25
3
2
5
4
20
6
7
Tx Rx
Rx Tx
RTS CTS
CTS RTS
DSR DTR
DTR DSR
GND
Cable
25/25 or
9/25 pin
IC-485ASIDevice's Connector Pin #