Maybe a special connecting cable must be soldered at first. Normally a DB9 socket is necessary for the connection to the COM interface of the PC.

DB9 female socket ( front view )

DB9 male plug ( front view )

Full-Duplex-Connection

Most of the devices can transmit data in both directions simultaneously. LIAN 98 and the test object work simultaneously as transmitter and receiver. None of both transmitters has to wait for clearance for transmitting data. Therefore the signals RTS and CTS are not significant. Sure, LIAN 98 is setting the control signals RTS and DTR to 1 when it is ready for transmission and receipt but it does not check the signals CTS and DSR.

Cable without "Handshaking".

The simplest way for the communication between two devices is a communication without the use of control signals. Only data lines and signal ground are connected, all other pins do not have a connection. Condition for the use of this simplified cable is that the test object does not check the control signals ( DSR, DCD ).

Cable with "Loop Back Handshaking".

If a device checks the signals DSR, CTS and DCD the connections between pin 4 to pin 1 and 6 and pin 7 to pin 8 are necessary. LIAN 98 does not use the DCD signal ( Data Carrier Detect ), this connection is optional. Normally the DCD signal indicates the existence of a communication connection between two modems and is also used by some devices ( substations, master stations, ... ).

This cable with "Partial Handshaking" works in most cases.

Half-Duplex-Connection

In case of a half duplex connection LIAN 98 as well as the test object can work as transmitter and receiver, hereby only one data line ( 2-wire connection ) is available that can be used alternately for transmission or receipt of data. The control signals RTS and CTS are used in order to define the allocation of transmission or receipt. When LIAN 98 should work as transmitter it activates the signal RTS and waits for the confirmation of the test object via the signal CTS. After the receipt of the signal CTS the data are transmitted and after the transmission of the data the signal RTS is set to 0. In each other case LIAN 98 is working as receiver only.

As long as the LIAN 98 software is ready for transmission and receipt the signal DTR is activated in order to show the partner that LIAN 98 is ready for operation, as well the software expects an activated DSR signal from the test object.

Cable for "Full Handshaking".

Modem-connection

The PC must be connected to the network hub or switch before LIAN 98 will be started, otherwise parametrization of the network in LIAN can not be done.