Lighting interface introduction about DMX512, DALI, KNX.

Home automation is more and more popular in recent years. We list some main interfaces by wire control below. To let you know more.

DMX512 Interface

Time-honored lighting control Interface, proposed by the American Stage Lighting Association in the 1970s. Before KNX was popularized, it was a popular dimming interface. It was used a lot in KTV and theaters. At the same time, it was also often used in outdoor decoration projects of general buildings.

1. Communication medium: RS485
2. Rate: 250kbps
3. 512of devices supported by a single line (in fact, we can’t say device by number channel, one address represents one function point. For example, one RGB light needs 3 channels)
4. The refresh mode is adopted, and there is generally no feedback (just send a signal, and send it continuously in a certain frequency range.)
5. Single-channel single-address, master-slave type.

DALI Interface

Focus on dimming, an Interface specifically for lighting. It is used more in engineering and construction, and it has developed from DALI1 to DALI2. The bus voltage usually is 15-23V. Generally speaking, the cost of the DALI interface circuit is relatively low, and a few capacitors, transistors, resistors, and optical couplers can complete the interface signal modulation. As a result, the DALI products of many companies in the market are not standard. Due to it being 1200bps, a cycle should be 833us/bit. But after testing, we found some products sold on the market have inaccurate dimming due to the long rise or fall time within 833us.

Generally, DT6 is for LED single color lights and DALI2 for LED lights can support two-color and RGB dimming. The early developers were mixed, resulting in poor compatibility of DALI products. With the advancement of the DALI Alliance, the standards will become more and more unified, and the situation will gradually improve.

Meanwhile, DALI addresses are automatically generated addresses and random. So we need to find out the address of the light.

1. Digital addressable lighting interface
2. Internationally published lighting control communication Interface
3. Rate: 1200bps.
4. Number of single-line supported devices: 64
5. Single lamp with a single address, generally master-slave, can also support controllers such as panels and sensors.

KNX Interface

In May 1999, the three major European bus protocols EIB, BatiBus, and EHSA merged to form the Konnex Association and proposed the KNX. It is the only global standard for home and building control. And provides complete solutions for home and building automation.

KNX and DALI are currently the best combinations in lighting. The advantage of KNX is that the configuration method is relatively complete and unified, and each manufacturer’s product can use ETS software to configure, while DALI is only an interface protocol, there is no unified configuration tool, and the software needs to be developed separately by each brand. Since DALI is specifically aimed at lighting and dimming scenarios, the protocol stack has a good application in lighting. And the cost of DALI is lower than that of KNX. But since the DALI address is randomly generated, there needs to be a step to finding the light. If there is a problem, the configuration is more troublesome.

1. Intelligent Building Construction Standards
2. Rate: 9600bps
3. Number of devices supported by a single line: TP1-265 can be extended to 65535 devices.
4. Distributed, no master-slave distinction