DMX 512-A / 1990 compatibility

[gomlight]

Hi,

Can I use in the same network devices using DMX 512-A and devices using DMX 512 1990?

In the DMX 512-A we can read that this protocol is not appropriate for hazardous application is it always true with the RDM?

Thank you
gom

[prwatE120]

Provided the products actually comply with the two standards, there should be no real reason not to mix old and new on the same network. Such compatability was a REAL concern for the task group when we created DMX512-A.

One caveat, however. Caution is required when using Transmitters whose outputs are "isolated" or "floating" in conjunction with Receivers that are "isolated" or "floating", as you may end up with NONE of your screened cables' screen connected to chassis or earth.

The latest standard recommends the use of the "grounded Transmitter/ isolated Receiver" topology.

In answer to your second question, RDM does NOT make the Null Start code packets on a DMX link any more robust. Test packets and SIPS (as defined in DMX512-A) allow some qualification about the quality of your links, but I would still not advocate the generic use of DMX as a control protocol in "hazardous" applications.