In the production of equipment DMX512 no definite standard for connecting lines total and ground wire to the zero power or grounding device case. EIA485 standard requires that the line land direct connection to the land lines supply voltage as a receiver and a transmitter. Exception may be made in the case when the applied voltage does not exceed certain values. In practice, this means that manufacturers often make the connection of land supply voltage line and leave ╚ ╩ land in the device under the floating potential.
The earth (zero) wire line must be connected to the zero point of the supply voltage of the transmitting device in most systems DMX512 (with the exception of transmitting devices on battery power, testers, etc.). This should be done for reasons of reducing the influence of external interference and to increase electrical safety. EIA485 Standard also specifies that the line at the other end can be connected to the zero point of the receiving device. This usually can lead to some specific problems when using large-scale systems - from errors in the reception signal to catastrophic failures.
When installing the network DMX512 is important to determine in advance from any device connected to the cable shielding to the zero point of electric power, and have no - no. This can be done simply by checking the conductivity between pins 1 connector DMX and zero point of the device (or corps).
In that case, if all devices (except the transmitting device - consoles) isolated from the zero point of the supply voltage is usually not required to carry out any action to ensure reliable operation of the system. In the same case, when one or more devices connected to the zero point, may be necessary to install special circuitry on an insulating portion of the network DMX512 or the entire network as a whole.
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