Doug Fleenor Design DMXOPTO-5 - Manual (Page 2)

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PRODUCT DESCRIPTION
The DMX512 Optical Isolator (DMX Opto Isolator) provides complete
electrical isolation between lighting consoles and associated
dimmers when installed in the control line. The electrical
connections is broken by using an optocoupler which passes the
control signal using a beam of light. Designed to protect the
console from damage in the event of dimmer failure, the Opto
Isolator may also be used to eliminate ground loops, protect
against lighting damage, and buffer the DMX signal at control
line intersections (wyes).
The input stage of the DMX Opto Isolator is passive. The United
States Institute for Theater Technology (USITT) standard for
DMX512 calls for the input of a receiving device to meet EIA-485
specifications. The DMX Opto Isolator's passive input does not
adhere to EIA-485, and so it's input does not strictly meet the
DMX512 specification. See this manual's section on installation
for more information on the Opto Isolator's input, why it doesn't
meet DMX512, and why it doesn't need to.
The DMX Opto Isolator uses a 10,000 Kilo Baud optocoupler. The
DMX512 data rate is 250 Kilo Baud. The reason for using such a
high speed optocoupler is to insure that the DMX Opto Isolator
does not introduce any signal degradation, even when several are
daisy-chained together.
The DMX Opto Isolator's output section is fully DMX512 and EIA-
485 compatible. The output driver is also capable of 10,000 Kilo
Baud operation.
SETUP AND CONNECTIONS
The DMX Opto Isolator is designed to be placed as close to the
console as possible. In fact, it is possible to plug the
isolator directly into the output jack of the console, and the
control cable onto the end of the isolator. This method of
connection eliminates the need for any additional cables.
In some installations, the console is too close to the wall to
allow the isolator to "hang off the back". In other cases the
likelihood of damage to the "extended connector" makes the direct
installation unwise. In these cases, a short (1 to 2 meter)
DMX512 cable may be used between the console and the isolator, so
that the isolator may be placed on the floor or table near the
console. (The isolator does not need to be close to the console
for proper operation. However the longer the cable between the
console and the isolator, the less protection the isolator will
provide from electro-magnetic induction).
The DMX512 input to the isolator is a male 5 pin "XLR" style
connector, the output is a female 5 pin connector. These are the
connectors specified in the DMX512 standard. The mating
connector for the input to the isolator is a female 5 pin
connector such as the Switchcraft model A5F. The mating
connector for the output from the isolator is a male 5 pin
connector such as the Switchcraft model A5M.