Dimming – Digital Serial Interface (DSI) – (DD2)

The Digital Serial Interface (DSI) system was launched into the lighting market back in 1992 by Tridonic and is a more controllable version of digital dimming, which enables the user to group luminaires, operate daylight linked dimming as well as other control options. The term DSI is a Tridonic name which can be set up with a variety of controls and controllers, some of which are offered by other manufacturers but designed to work with the DSI control gear. When launched, was the first use of digital communication in lighting control, and is the precursor to DALI.

DSI uses a protocol for the controlling of lighting where the technology utilises a single byte digital signal to communicate and alter the lighting level to that required, and this eliminates sources of error like voltage drop in the signal cable as well as errors in linearity. The system ensures that there are no issues with interference from the switching and the dimming of the luminaire which can affect switch on and is wired using a dimming pair, run around to each luminaire in the circuit.

For the installation of a DSI system, there is a requirement for a standard Twin & Earth cable to provide the power of Live, Neutral & Earth to the light fitting as well as an additional twin wire control cable. One further requirement is to always use a DSI controller.

There are some advantages with using the DSI system, in that there are no error sources from voltage drop in the control cable and no risk of any polarity errors. The lighting can be operated by using the signal cables, which means that the feeder voltage conduits can be placed independently from the signal cables. This allows for smaller and cheaper regulator units, which can control a relatively large number of luminaires. The system is well-suited to renovation and where the layout changes frequently.

In DSI installations where the addition of emergency lighting is a requirement, one advantage is that the mains voltage can be permanently connected all the time and can therefore provide the charging facility for the luminaire batteries.

One of the disadvantages of installing a DSI system for the smaller application is that of cost as this can often be fairly high, due to the requirement of the digital DSI controller, which must be used for all installations, therefore where this becomes an issue, it is suggested that for the smaller systems, Switch-Dim is the preferred option.

Using a Switch-Dim lighting system can provide an ideal solution for many smaller applications, such as, offices, or for stairwells and corridors, as well as for the smaller warehouse or storage area facility.