The relationship between DMX and RDM
RDM is an extended version of the DMX512-A protocol. The RDM protocol is a remote device management (Remote Device Management) protocol. It is formulated by the American National Standards Institute (ANSI) and is based on DMX512-A. DMX512-A can be regarded as DMX for two-way data transmission. Under the RDM protocol, the control system can send requests to the lamps and the lamps can also respond to these requests, and the settings of the lamps can be changed on the console. Every RDM-compatible lamp can be identified by its built-in unique identification code; the list content is likely to include the lamp model and the number of DMX fields it needs. Including the ability to remotely set the initial address of DMX512, status monitoring and management of these devices.
Reasonable use environment of RDM system:
RDM system rational use environment regardless of landscape effect design, lighting manufacturing, engineering design, construction specifications and many other links must attract sufficient attention.
1. DMX512.-RDM is a two-way transmission communication with risk
DMX512 communication is based on RS485. Usually, the host sends dynamic image signals in simplex mode. The lamps are only in the communication receiving state. At the same time, the RS485 bus network is always in the master-slave structure. When the RS485 bus is long, a terminating resistor must be added to ensure the signal stability. This method has extremely high reliability. The RDM system is a two-way transmission. Because the feedback signal needs to be transmitted back to the host, the master-slave structure of the RS485 bus network has been destroyed. That is to say, every lamp can be used as the host at every moment. If the RS485 bus compares Short, (for example: about 100 meters) two-way transmission will not affect too much. If the RS485 bus is relatively long, signal reflection interference will be large (for example: greater than 100 meters) DMX512 communication baud rate is 250K. It is difficult to add termination resistors to ensure signal stability.
Analysis: The risk of two-way transmission in the RDM system cannot be ignored.
2. Number of lamps controlled by RDM system
Chinese LED landscape lighting projects with more than 10,000 lamps can often be seen. If the simplex DMX512 communication method is used, it has extremely high reliability. If the duplex DMX512-RDM communication method is adopted, due to the large number of lamps, higher quality requirements will be put forward for many links such as lamp production, communication network design, construction quality assurance and so on. Based on the analysis of the overall professional quality of my country's relevant LED landscape lighting industry, I hope that people in the industry must have a clear understanding.
Analysis: If you have full confidence in the company's overall professional quality, it is recommended that the RDM system should not exceed 5000 sets of lamps.
3. RDM system lighting installation environment
China’s LED landscape lighting projects are mainly used outdoors. Due to the fragility of the two-way transmission of the RDM system, the RS485 bus network has been exposed to wind and sun for a long time. Therefore, ensuring the long-term and reliable operation of the RDM system two-way transmission brings risks. It is recommended that your company is the first It is best to use RDM system in indoor environment. In addition, in the past, the DMX512 (RDM-free system) control system often used products (including; system software, main control, sub-control, signal amplifier,,,,) after adopting the RDM system, it needs to be reconfigured (including; system software, main control) , Sub-control, signal amplifier……)
Analysis: It is recommended that if your company adopts the RDM system for the first time, it is best to apply it in an indoor environment.
4. RDM system lamp feedback signal
People in the industry often misunderstand RDM systems and feedback signals. RDM belongs to remote equipment management, while lamp feedback signals are only part of equipment management. For example: RDM commands include: change and set the DMX start address of the lamp; get the status of the DMX device; the information of the lamp manufacturer, etc. Regarding the lamp feedback signal, it is even more demanding that the lamp feedback signal has voltage, current, color temperature, temperature of each LED light source, faulty parts of the lamp, etc. We are not aware that what we are facing is only a lighting fixture, not a "robot". Therefore, the fierce collision between the technical feasibility of RDM system and business operation is everywhere.
Analysis conclusion: The fierce collision between technical feasibility and business operation tests the career bottom line of every technical professional.
RDM system application analysis conclusion:
It is beyond reproach that DMX512.-RDM is a mature technology. Facing this mature technology, as electronic communication engineers, they should be fully prepared for professional technology. It needs to be emphasized again that DMX512.-RDM belongs to two-way communication technology, while DMX512.- belongs to one-way communication technology. There is a huge difference between the two in terms of communication reliability. DMX512. One-way communication system and lamps only transmit image signals on one line. Complete the task successfully. However, the DMX512.-RDM system and lamps are in one line, which contains dual tasks. It not only needs to transmit image signals, but also takes into account the feedback signal back to the host. The communication system has certain risks.
Sincere advice: If you have full confidence in the company's overall professional quality, if your company adopts the RDM system for the first time, it is best to apply it in an indoor environment. It is best not to exceed 5000 sets of lamps.
