OSI Physical Layer · Data Communications

DATA TRANSMISSION MODES

// INTERACTIVE VISUALIZATION — SELECT A MODE BELOW TO EXPLORE
// SIMPLEX · HALF-DUPLEX · FULL-DUPLEX · ANIMATED SVG

192.168.1.1 TX RX DEVICE A TRANSMITTING 192.168.1.2 TX RX DEVICE B RECEIVING NO SIGNAL ⊘ ─── ─── ─── ─── ──▶ ◀── ─── ─── ─── ─── TRANSMISSION CHANNEL A → B switching in 3.0s A→B PACKETS: 0 B→A PACKETS: 0 EFFICIENCY: 50% MODE: SIMPLEX
SPEED: 1.0×
A→B 0 pkts
B→A 0 pkts
CHANNEL: SIMPLEX
DIRECTION: UNI-DIRECTIONAL
THROUGHPUT: 50%
DEFINITION
SIMPLEX MODE

In simplex mode, data transmission is strictly one-directional. Device A can only transmit; Device B can only receive. The return channel is permanently unused. This is the simplest and cheapest form of communication but offers no feedback capability.

CHARACTERISTICS
  • One-way data flow only — sender cannot receive
  • Full bandwidth dedicated to single direction
  • No handshaking or acknowledgement possible
  • Lowest hardware complexity and cost
  • No collision possible on the channel
CHANNEL UTILIZATION
A → B
100%
B → A
0%

Total channel efficiency: 50% of theoretical maximum

REAL-WORLD EXAMPLES
📺TelevisionBroadcast signal tower → TV set only
📻AM/FM RadioStation → listeners, no reply
🖨️Printer PortOld parallel port (LPT), data out
🚦Traffic SignalsControl center → signals only
// TIMING DIAGRAM — TRANSMISSION ACTIVITY OVER TIME