B&B Electronics 232MSS2 manual Port Configuration, DCE Master Port Chart C & D Ports

Port Configuration

In order to determine the proper port configuration of the 232MSS2, it is necessary to have a basic understanding of the terms DCE and DTE. RS-232 was designed, using DB-25 connectors, for connecting a DTE (Data Terminal Equipment) device to a DCE (Data Communication Equipment) device. Each device will have inputs on pins that correspond to outputs on the same pins of the other device. For example, a DTE device will transmit data out on pin 2 (on a DB-25) and a DCE device will receive data in on pin 2 (on a DB-25). IBM PCs and serial printers are DTE devices, modems are DCE devices.

If an IBM PC (DTE device) is going to be connected to the 232MSS2 master port, the master port should be configured as a DCE port. If a modem (DCE device) is going to be connected to the master port, it should be configured as a DTE port.

The master port can be configured as a DCE port (data received on pin 2) or a DTE port (data received on pin 3) by setting dipswitch “SW1”, position 8. To configure the master port as a DCE port, move dipswitch “SW1”, position 8, to the "OFF" position. When the master port is configured as a DCE port, ports A, B, C, & D will become DTE ports (Refer to Table 2). To configure the master port as a DTE port move dipswitch “SW1”, position 8, to the "ON" position. When the master port is configured as a DTE port, ports A, B, C, & D will become DCE ports (Refer to Table 3). Always power down the smart switch when changing switch settings.

Table 2. DCE MASTER PORT CHART

Master Port				A,B,C & D Ports
	(DCE)		Signal		(DTE)
Pin#		Direction	Description	Pin#	Direction
2		Input	Transmit Data (TD)	3	Output
3		Output	Receive Data (RD)	2	Input
4		Input	Request to Send (RTS)	7	Output
5		Output	Clear to Send (CTS)	8	Input
7		<------->	Signal Ground (SG)	5	<----->

4Documentation Number 232MSS2-0108 Manual

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