FUTABA FDL01TU, Instruction Manual

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3.1
Data Transparent Mode
3.1.1 What Is Data Transparent Mode?
In data transparent mode , the FDL01TU modems are continuously connected in a 1:1
configuration. Full-duplex communication is simulated between the two terminals using a
method in which each modem rapidly switches between transmitting and receiving
(referred to as Time-Division-Duplex (TDD) transmission).
With the exception of FDL01TU modem commands, all data input from the sending
terminal are transmitted to the receiving terminal. Using this mode, the user can simply
replace a serial cable with a pair of FDL01TU modems and communicate without any
special software or hardware requirements.
3.1.2 Time-Division-Duplex Transmission and ARQ Function
As noted above, when in data transparent mode , data packets are exchanged between
terminals the modems rapidly switching between transmitting and receiving, simulating
full-duplex communication.
Data input to the sending FDL01TU modem are assembled together with error detection
bits and other control data, and then transmitted to the receiving modem. If an error is
detected by the receiving modem, it will continue to request retransmission of the packet
from the transmitting modem until it receives a valid packet. This is referred to as the
Automatic Retransmission Request (ARQ) function. The ARQ function greatly enhances
the reliability of the wireless connection because it ensures that the receiving FDL01TU
modem will not pass corrupted data on to its terminal.
Figure 3–1: Send/Receive Timing Diagram
3.1.3 Connection Method
Link is connected and disconnected with the CON and DCN commands. Receiving
modems can be shifted among many others by designating station addresses.
Wireless Modem A send receive send receive send
Wireless Modem B receive send receive send receive
packet length A packet length B
time (t)