Most of the problems when using the standard DMX512 is connected with incorrect use of terminators, improper cabling, and the emergence of spurious contours on failed grounding. Before you begin to hold a full range of sophisticated tests to detect the causes of failure, we recommend that the following simple checks.
Not connected if too many devices on the line? Is it too loud it load? This can happen when the line is somewhat DOL devices. If these devices do not apply, then in one line can be up to 32 devices that meet standard EIA485.
Is there a terminator in line? Terminator should be one on the far end of the line. The resistance of the terminator should be about 120 ohms.
Are all the wires in the cable connected to both terminals? Devices operating with DMX512, usually continue to work even when not connected to the conductor with inverted data (pin 2). However, in most cases there are faults in the system.
There is not whether any of the signals data? This usually leads to the fact that the normal operation of the system is interspersed with random flashing, etc.
Does the use of optical isolation to decrease or complete disappearance of the problem? If so, then most likely your system has suffered because of the formation of spurious contours with the closure through the ground. Perhaps you should pave the way power cables to reduce this effect. In addition, it may be necessary to use optical isolation on some lines DMX512, or even the entire network.
Oksid.ch - All about DMX 512
Other Protocol Packets
Terminators and their installation