Documentation Number 232MSS2-0108 Manual
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics Ltd – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445
4
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 (
D
ata
T
erminal
E
quipment) device
to a DCE (
D
ata
C
ommunication
E
quipment) 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
(DCE)
Signal
A,B,C & D Ports
(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
<----->
