TRANSMISSION MODE

TM 11-7010-207-23

2-4. TRANSMISSION MODE

Communication between converters can be in either of the following modes:

Simultaneous two-way transmission using a 4-wire

a. 4-Wire Full Duplex.

circuit.

b. 4-Wire Half Duplex.

Alternating two-way transmission using a 4-wire

circuit.

2-5. CARRIER CONTROL

The 600GR converter can be switched by means of the configuration switch (S2) to

operate in a Constant Carrier mode or in a Switched Carrier mode.

a. Constant Carrier Operation. When a converter board is switched to a

constant carrier mode, the transmitter is always on. The CLEAR TO SEND (CTS)

signal is always on. When data is received from the associated DTE, transmission

of data takes place. The Transmitter Data (TO) indicator lights until data

transmission stops. At the receiving end, the Receive Data (RD) indicator lights

to show that data being transmitted from the distant end converter is being

received. Transmitted spaces cause the TD and RD indicators to flicker during data

transmission.

b. Switched Carrier Operation. When a converter board is switched to a

switched carrier mode, the functioning of the transmitter is controlled by

Request-to-Send (RTS). If the attached terminal does not supply an RTS, signal

switch S2 must be switched to the RTS ON position.

2-6. POWER SUPPLY

Each converter board has a self-contained power supply which supplies the required

+5v, -5V, +12V, and -12V logic voltages. Primary power is supplied through the

rear panel. Primary power is supplied through the board connector by way of a

12-connector strip. The unit is protected by a slow blow fuse accessible from the

rear.

2-7. FUNCTIONAL TESTING

Transmitter and receiver operation can be partially checked by means of the two

position NORM/LPBK switch on the front panel. For a self-test check the NORM/LPBK

switch is placed in the LPBK position. Transmit data from the local terminal goes

to the converter's transmitter (TX) as shown in figure 2-2, and is looped back to

the receiver (RX). At the same time, if data is being transmitted from the distant

end, data from the remote terminal goes to the local converter's receive amplifier

and is looped directly back to the converter's transmit amplifier, testing both

converters and the transmission lines.

In the NORM position, the converters receive and transmit data over the

communication lines.

2-3