IV Connector and signal
Conforming to EIA RS-232 and CCITT V2.4 standards.2-3 pin for data sending and
receiving, 7-8 pin for RTS and CTS, 4-1 pin for DTR and DCD, 6 pin for DSR and 5 pin for
GND. RS-232 interface (TO DTE): Connector: DB-25/9 hole-shaped connector to be used.
Signal: interior signal cables are separated.
1. Model selection
First of all, you have to get a clear idea of which signal cables are used by your RS-232
system, then you can select the proper model isolator to protect your communication
system. For example, for the terminal of the traditional 2, 3 and 5 lines, you can select the
isolator which supports 3-line-2-cable 1-receive-1-send mode. And for the 5 line terminal of
2, 3, 4, 5 and 7, you can select the isolator which supports 5-line-4-cable 2-receive-2-send
mode.
2. Connection method
RS232 optic isolator can be connected in series with between the serial connection cable of
the previous RS-232 and the RS-232 interface, and either end is OK but you have to pay
attention to the direction indicated by TO DTE or TO DCE. Generally speaking, PC user
and multi-user are DTE devices; MODEM and terminal are DCE devices, however this
general rule dose not apply to all situations. To decide DTE or DCE devices, you have to
base your conclusion on the signal cable of your devices RS-232 interface. For example, it
is DTE for the signal output from DB25 interface pin 2, while its receiving input is DCE.
Therefore, if crossed RS-232 cable is used to connect two DTE devices (e.g. terminal and
multi-users), you have to connect the TO DTE end to the device and TO DCE end to the
cable, no matter which side, and your RS232 optic isolator is connected.
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