Digital Signal Interface (DSI) is a protocol

Communications protocol

A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...

 for the controlling of lighting in buildings (initially electrical ballast

Electrical ballast

An electrical ballast is a device intended to limit the amount of current in an electric circuit. A familiar and widely used example is the inductive ballast used in fluorescent lamps, to limit the current through the tube, which would otherwise rise to destructive levels due to the tube's...

s). It was created in 1991 by Austria

Austria

Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...

n company Tridonic and is based on Manchester-coded 8-bit protocol, data rate

Data rate

Data rate can refer to:* Bit rate, or data transfer rate* Data signaling rate* Data rate units-See also:* Baud rate* Channel capacity* Throughput* Bandwidth everything in this page is falsified...

 of 1200 baud

Baud

In telecommunications and electronics, baud is synonymous to symbols per second or pulses per second. It is the unit of symbol rate, also known as baud rate or modulation rate; the number of distinct symbol changes made to the transmission medium per second in a digitally modulated signal or a...

, 1 start bit

Bit

A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...

, 8 data bits (dimming value), 4 stop bits, and is the basis of the more sophisticated protocol Digital Addressable Lighting Interface

Digital Addressable Lighting Interface

Digital Addressable Lighting Interface is a technical standard for network-based systems that control lighting in buildings. It was established as a successor for 0-10 V lighting control systems, and as an open standard alternative to Digital Signal Interface , on which it is based...

 (DALI).

The technology uses a single byte to communicate the lighting level ( 0-255 or 0x00-0xFF). DSI was the first use of digital communication in lighting control, and was the precursor to DALI.

Advantages

• Its simple nature makes it straightforward to understand, implement
  Implementation
  Implementation is the realization of an application, or execution of a plan, idea, model, design, specification, standard, algorithm, or policy.-Computer Science:...
  
  , and diagnose
  Medical diagnosis
  Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...
  
  , while its low voltage means it typically runs along relatively thin cables.

• Because each device has its own wire to the controller
  Controller (computing)
  In computing and especially in computer hardware, controller is a chip, an expansion card, or a stand-alone device that interfaces with a peripheral device...
  
   (rather than being part of a network
  Computer network
  A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
  
  ) it has no need of an address to be set, so can be replaced simply by unplugging the faulty one and plugging in the new.

• It dims to off, so does not require mains switching equipment to turn them off.

Disadvantages

• It requires one wire per control channel so a sophisticated system could have hundreds of wires, thereby making diagnoses of problems difficult.

• It is a proprietary
  Property
  Property is any physical or intangible entity that is owned by a person or jointly by a group of people or a legal entity like a corporation...
  
   standard initially exclusive to Tridonic and mainly brands of Tridonic's parent company Zumtobel.

Rival protocols

• DALI
  Digital Addressable Lighting Interface
  Digital Addressable Lighting Interface is a technical standard for network-based systems that control lighting in buildings. It was established as a successor for 0-10 V lighting control systems, and as an open standard alternative to Digital Signal Interface , on which it is based...
  
  
• 1-10v analog

DALI

DALI is an open standard

Open standard

An open standard is a standard that is publicly available and has various rights to use associated with it, and may also have various properties of how it was designed . There is no single definition and interpretations vary with usage....

for digital control of lighting. Several companies have adopted the DALI protocol in their product offerings. Even though DALI is an open standard, there are already versions of its implementation emerging in different lighting manufacturers products as they strive to provide a point of difference. DSI is essentially the same technology as DALI in terms of messaging, however, DSI eliminates the individual addressing aspect of each light fitting found in DALI.