Fixture one and shapes

[alcrooks]

Hi all,

 

Something I noticed the other day when I was programming a slow movement chase with mac 500s.

The Macs assigned to fixtures 1 to 4 were running the same movement shape, circle, but fixture one was moving very jerkily.

I swapped it out for a spare but that also showed the same behavior, and eventually got round it by giving it the same address as the next one up (17), and reversing pan and tilt, which worked fine...any ideas?

[Paul]

I'm guessing you have Fixture 1 patched to DMX address 1, as you have Fixture 2 patched to DMX address 17. The problem might be with the fixture not always receiving DMX correctly at low DMX addresses - it misses packets and hence gives jerky motion. Try patching Fixture 1 to a higher DMX address.

[alcrooks]

Is this a general dmx thing, a mac thing, or a frog thing?

 

Cheer

 

al :twisted:

[Paul]

The Frog DMX output conforms to the USITT specifications, as I'm sure does the MAC input. It might be more of a system problem - use of audio instead of DMX cable, missing end-of-line termination, ground loops, over-long cable runs etc. Most of the time you get away with it, but these sort of problems tend to start showing up at boundary conditions - low or high addresses, start and end of long cable runs etc.

 

Re-patching the fixture to a higher DMX address will give the fixture more time after the DMX break before it has to extract it's data. This ought to determine whether the problem is DMX related, or is indeed a problem in the desk with fixture 1! Let us know how you get on.

[alcrooks]

Will do, although it's not a problem I've noticed on other desks.