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Analog to DMX outboard: Difference between revisions
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→Why are there two grounds?
m (the outboard for use on OB's that need more cleverness, but don't have a full desk available.) |
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* The [[Analog to DMX]] box expects a reference Gnd from wherever it gets it's signal, this can be used, in conjunction with the AREF of some microcontrollers, to boost or cut the difference between 'reference' and signal (channels), so that was given a separate line. Usually, just leaving this alone or common (i.e. pins 14 and 15 bridged) is fine - it's main reason for existance is to be used as part of a compensator for long cable runs making voltage drops. | * The [[Analog to DMX]] box expects a reference Gnd from wherever it gets it's signal, this can be used, in conjunction with the AREF of some microcontrollers, to boost or cut the difference between 'reference' and signal (channels), so that was given a separate line. Usually, just leaving this alone or common (i.e. pins 14 and 15 bridged) is fine - it's main reason for existance is to be used as part of a compensator for long cable runs making voltage drops. | ||
* The [[Analog to DMX]] also sends 0v ground out to it's controlling devices, so they can operate - rather than being boxes of variable resistors. | * The [[Analog to DMX]] also sends 0v ground out to it's controlling devices, so they can operate - rather than being boxes of variable resistors. | ||
*Compensation happens at the slave end. Doing it at the control end risks someone coming along sometime in the future, and splitting the channels off the lines - in a worst-case scenario, they then compensate for long lines, something gets more than 10v without expecting it... | |||