9. Technologies
HDMI20-OPTC series – User's Manual
68
9.4. Serial Management
9.4.1. General Information
There are two types of devices in general serial communication:
▪
Data Terminal Equipment:
Data Terminal Equipment (DTE) is an end instrument that converts user
information into signals or reconverts received signals. Typical DTE devices: computers, LCD touch
panels and control systems.
▪
Data Circuit-terminating Equipment:
Data Circuit-terminating Equipment (DCE) is a device that sits
between the DTE and a data transmission circuit. It is also called data communication equipment and
data carrier equipment. Typical DCE devices: projectors, industrial monitors and amplifiers.
Among others the pin assignment is different between DTE and DCE.
DTE
DCE
Pin 2:
RD
TD
Pin 3:
TD
RD
RD
: Received Data (digital input)
TD:
Transmitted Data (digital output)
Different type of serial cables must be used between different serial devices.
DTE
DCE
DTE
Null-modem
Straight
DCE
Straight
Null-modem*
* In general contact DCE with DCE by tail-circuit serial cable.
9.4.2. Types of Serial Cables
Straight Serial Cable
Null-modem Serial Cable
Straight pin-outs both ends.
Straight pin-out at the one end and cross
pin-out at the other end (interchange lines
of TX and RX).
Serial cables between devices may have male or female plugs and their type may be straight or null-modem
in usual.
ATTENTION!
The cable type does not depend on the plug type.
9.4.3. RS-232 Signal Transmission over Lightware Extender Devices
The following examples describe the detailed integration of Lightware devices between different RS-232 pin
assignment units.
INFO: Both HDMI20-OPTC-TX220-PRO and HDMI20-OPTC-RX220-PRO are DTE units (according to their pinouts)
with male plugs.
Extending RS-232 between DTE and DCE third-party devices
Connect null-modem serial cable between controller system (DTE) and the transmitter (DTE) and straight
serial cable between receiver (DTE) and projector (DCE).
RS-232 connection example between a controller system and a projector
Extending RS-232 between DCE and DCE third-party devices
Connect straight serial cable between controller system (DTE) and the transmitter (DCE) and null-modem
serial cable between receiver (DTE) and computer (DTE).
RS-232 connection example between a media player and a projector
Transmitter
Controller system
Projector
Female - Female
Female - Male
Transmission
interface
Straight serial
cable
Null-modem
serial cable
DTE
Pin 2: RD
Pin 3: TD
Receiver
DTE
Pin 2: RD
Pin 3: TD
Pin 2: RD
Pin 3: TD
DTE
DCE
Pin 2: TD
Pin 3: RD
Transmitter
Media Player
Projector
Male - Female
Female - Male
Transmission
interface
DTE
Pin 2: TD
Pin 3: RD
Receiver
DTE
Pin 2: RD
Pin 3: TD
Pin 2: RD
Pin 3: TD
DCE
DCE
Pin 2: TD
Pin 3: RD
Straight serial
cable
Straight serial
cable