I have find in documents that
"The DMX512 output is designed to feed 32 'units' of load."
but I know that DMX512 can handle 512 devices.
then what is 32 loads ?
Pls explain this....
DMX is a bus, so it has a limit to the number of loads that can be attached.
You may be confusing "channels" with "devices"
A load is a receiver.
A receiver takes current supplied by the transmitter. In the normal course of events the transmitter can supply 32 times more current than one receiver will take.
You can get half or quarter power receivers and so drive 64 or 128 receivers in a bus.
but I know that DMX512 can handle 512 devices.
That is only the software specification, that is that is then number the software can cope with. What the hardware can cope with is often, as in this case, very different.
so dmx can handle only 32 channels ?
for more than 32 channels, shall we need one more dmx ?
so dmx can handle only 32 channels
No, that's all that specified device can handle.
sorry sir, i didn't get it.. can you explain clearly.
why we use 512 and 32 in case of dmx ?
BECAUSE ONE IS A SOFTWARE SPECIFICATION AND THE OTHER IS A HARDWARE SPECIFICATION.
You can change the hardware by having high current drivers or low current receivers or both. But you can't change the software, that has 9 bits reserved for the address in the protocol so you can never have more than 512 devices no matter how much current you supply to the bus.
then can we run 512 devices with dmx or only 32 devices ?
You can run 512 devices with DMX IF the hardware you have is up to it.
Now if your hardware says only 32 loads and you have normal current loads then you can only run 32 devices despite the protocol being capable of running 512 devices.
Suppose you're controlling lights, and you're using 4 channel dimmer packs, which are pretty common.
You could connect 32 of these 4 channel boxes, assuming each is a full unit load (some products may be half or quarter load). Since each box controls 4 lights, at 32 boxes you'd be limited to 128 channels, or 128 lighting circuits you could control.
But suppose you used 8 channel boxes, and they were each only a quarter load. Even though you could connect 128 of these boxes before reaching the 32 unit load limit on the wire, since each box implements 8 channels, as soon as you connect only 64 of these boxes, you would use up all 512 possible channels.
There are also repeaters, which are basically just amplifiers for the signal. They allow you to drive another 32 unit loads with a copy of the original signal, which gets you around the 32 unit load limit.
The 32 unit load limit is a good thing to observe, but in practice you can often get away with driving more than 32 (much like how many computers can be overclocked), though that's not recommended. And realistically, if you've gone to the trouble and expense to connect and configure that much equipment, it's probably only a tiny bit more to use repeaters or quarter load devices.