What hardwhere could i do this with

hi all,

i want to control some old furse lighting dimmers they are controled by fmx, i need some pointers on what i could use with 4v to get this control siginal , the spec is below

The protocol is based on channel ‘bytes’ of 560us wide. Each ‘byte’ is made up of eight 70us ‘bits’. ‘Bits’ are output in the order 1-8.
The ‘bits’ have the following function within a ‘byte’:

Synchronisation ‘byte’: Bit 1 & bit 2 - +12V
Bits 3 - 8 - 0V

Null ‘byte’: Bit 1 - +12V
Bit 2 - 8 - 0V

Channel data ‘byte’ Bit 1 - +12V
Bit 2 - 0V
Bits 3 - 6 - Channel data level (see Note)
Bits 7 - 8 - 0V

Note: The channel data level is 0V for full brightness and +10V for zero brightness.

The ‘bytes’ are output in the following order:

Sync, null, channel 1, channel 2, channel, 3, channel 4, channel 5, channel 6,
null, null, channel 7, channel 8, channel, 9, channel 10, channel 11, channel 12,
null, null, channel 13, channel 14, channel, 15, channel 16, channel 17, channel 18,
etc. for up to a maximum of 96 channels, then the pattern repeats.
There is no gap between ‘bytes’.

The standard connector for these racks is a 5 pin ‘bleecon’ connector (like a 5 pin din, but latching). There is a socket both on the rack and on the desk.
The pinout is Pin 1 = +24V, Pin 2 = -24V, Pin 3 = 0V, Pin 4 = Analogue control signal (as described above).


fmx_1.bmp (122.2 kB)

hi henny… you say this to be Fmx
so i suppose nothing to see with Dmx.

if this is really Fmx what is the mark of those strange dimmers ? knowing constructor would really help more … ( or an old school god of signals, Kalle ? )

there was HERMES for processing electronically conversion of signals between 0/10v analogic / D54 / AVAB signal ( dont remeber its name) …
(photo here but didnt found any doc)


Back Before DMX 512 became the norm there were quite a few mutiliplex control systems about

D54 - that strand used
and FMX that furse used , the dimmers in question are furse regal dimmers

and i do need that 12v for the sync byte.


hi henny maybe this could help ( tel)

i been a member of the blue room for years. and that where i foun the above FMX spec

there is a user on there that has developed a dmx-fmx converter , with any luck he may share his designs.

i just want to test 3 rack of 20 ch to see if they work before i put tooo much work in to it

so was after some way of generating the siginal

sorry not to be of any help :-’

well, i thought about faking this data using dmx because the bit-timing of dmx is known.

but this won’t help with ^Bits 3 - 6 - Channel data level^ at all.
and that 12V thing…

isn’t there any possibility of connecting an ordinary 0-10V demultplexer to analogue inputs?

for sure you can buy a cheap, old dimmerpack but if you’d calculate the time you spend in repairing this you must come to the conclusion that it is cheaper to buy a brand new, reliable one.

IMNSHO i wouldn’t spend any money into cheap, old crap equipment anymore.
i myself have a garage full of old equipment which i wanted to repair/modify one time. if somebody around here needs broken smoke machines, loads of used harting connectors , Solid state relais, single luminaires, ancient disco fx, hundreds of kilograms used load multicore cable: come and visit me.

i have 3 Betapacks similar to this one but without DMX. If somebody has interest…

dmx4all has the cheapest demultiplexors. dont know if its better than their horrible dmx interface ( brrrr )
gateway has very low cost dimmers product also


what i wanted to do was to test theses dimmeers and see what state there in, they look ok but without testing , and if they test out ok i think its worth spending £200 per dimmer upgrading to dmx. because it going to cost a wole lot more to swap out 72channels of dimming.

from what i gathere when the dimmers were last used 10-15 years ago they were fine it was just the desk that died.


hi henny,

do you have access to that broken desk?

perhaps you could use just the output circuits…

sadly no other ideas to do this ‘on the fly’.

or via arduino? but for sure this is also some effort in soldering and programming…