MDC›128
MIDI TO DMX CONVERTOR
User Guide
User Guide MDC-128
Features of the MDC›128
l Converts any complete MIDI channel to DMX
l Works from NoteOn/NoteOff or Control Change
l Velocity converts to brightness
Installation.
Connect the MDC-128 to the mains with the lead supplied.
l Brown = live
l Blue = neutral
l Green/Yellow = earth
l The MDC-128 must be earthed.
Connections:
Connect the MIDI signal to the MIDI IN socket using a standard MIDI lead.
Connect the MIDI THROUGH socket to other items in the MIDI chain using a
standard MIDI lead.
Connect the DMX output to the first item of DMX controlled equipment using a
screened twisted pair lead fitted with an XLR plug.
Please note that the MDC-128 does not have an audio input. Do not connect an
audio signal to any of the sockets on the back of the unit. Connection of an audio
signal may result in damage to the internal circuitry.
Operation
Setting the MIDI channel.
The MDC-128 converts one entire MIDI channel to DMX. Select which channel
you wish to convert on the switches on the back of the unit.
Midi Channel Switches on
(All other switches off)
1 NONE
2 1
3 2
4 1, 2
5 4
6 4, 1
7 4, 2
8 4, 2, 1
9 8
10 8, 1
© N.J.D. Electronics 1996 -Page 3-
MDC-128 User Guide
11 8, 2
12 8, 2, 1
13 8, 4
14 8, 4, 1
15 8, 4, 2
16 8, 4, 2, 1
The MDC-128 can either convert NoteOn and NoteOff messages to DMX, or it
can work from Control Change messages. Set the C/N switch to ON if you want to
use Control Change messages, or to OFF if you want to use NoteOn/NoteOff
messages.
Setting the DMX address switches on DMX controlled lighting.
DMX equipment has a set of switches (similar to the MIDI channel select
switches) to set the DMX address. Set these switches to one more than the Note
Number that you wish to use to control the lighting. (If you are using control
change messages as above, set the DMX address switches to the controller
number that you wish to use). Most DMX lighting allows addresses to be set to
any number from 1 to 256, and some allow up to 512. The MDC-128 converts all
128 notes on a midi channel to DMX, so must be used with DMX addresses below
128. By setting the DMX addresses to different note numbers, different notes can
be used to control different lighting products.
The MDC-128 converts the Midi Velocity (or controller data) to DMX data. MIDI
velocity and data only range from 0 to 127, to convert this to DMX data which
ranges from 0 to 255, the MIDI data is doubled.
Many DMX lighting effects require more than one DMX address, and these will
be controlled by more than one MIDI note (or controller) number. In this case the
Address switches set the first note number, and the unit responds to this note
number and three more notes immediately above.
For instance, the NJD IQ500 requires four DMX addresses, so it will be
controlled by four midi Notes (or controls). The DMX address switches will be set
to the first note number, 49 for example, by setting switches 32 and 16 ON on the
back of the IQ500. Note number 48 (C) will then control the pan mirror of the
IQ500, Note number 49 (C#) will control the tilt mirror, Note number 50 (D) will
control the colour and note number 51 (Eb) will control the gobo.
A second IQ500 could then be used with its DMX address set to 53, (by setting
switches 32, 16 and 4 ON). This would be controlled by Note number 52 (E) (pan
mirror), Note number 53 (F) (tilt mirror), note number 54 (F#) (colour) and note
number 55 (G) (gobo).
For further information on DMX addresses and data please refer to the User
Guide of the Lighting equipment that you are using.
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User Guide MDC-128
The colours on the IQ500 are controlled as follows:
Colour DMX data Midi velocity
Magenta 0 - 31 0 - 15
Yellow 32 - 63 16 - 31
Cyan 64 - 95 32 - 47
Pink 96 - 127 48 - 63
Green 128 - 159 64 - 79
Red 160 - 191 80 - 95
Blue 192 - 223 96 - 111
White 224 - 255 112 - 127
Because the maximum velocity is 127, the velocity is doubled to arrive at the
DMX data.
Sending a Note On message for note number 54 at velocity 70 will set the
colour of the second IQ500 to green. Or, if control change operation is selected,
sending a control change messafe for controller number 54 with the controller data
set to 70 will set the colour of the seconds IQ500 to green.
DMX.
The DMX system is a high-speed digital data system, which can transmit all the
information required for light dimmers, multi-motor lighting effects etc. down a
single cable. The IQ250 outputs a DMX signal when operating from its own
microphone, which can be used to synchronise other IQ250s. There is no limit to
the num ber of units that can be connected to the DMX signal, but it is not
recommended that the total cable length should exceed 250m. Each unit
connected to the DMX s ignal is given an address, and it compares this to the data
being sent on the DMX cable, so it can determine which data is addressed to it. It
then uses this da ta to move a motor or set a brightness level as required by the
controller. As the DMX system can transmit as much information as 512 analogue
control wires dow n a single cable, it has to transmit very quickly, in fact, at a
frequency 12 times higher than the highest audio frequency. Anyone who has
used long leads for audio will realies that it is difficult to do without losing the
higher frequencies. To make the DMX system work at such high frequencies, it
requires special c ircuitry and special cable. Cable can be designed to pass high
frequencies with no loss if it has the correct resistance connected at each end, this
resistance is called the characteristic impedance of the cable. DMX cable has a
characteristic impedance of 120W. All NJD DMX products are designed to ensure
that the resi stors are connected automatically. Without them, the signal reflects off
the end of the cable and interferes with the new data coming the other way. If the
cabl e is not correct, the system will not work. Most good quality low-capacitance
screened twisted pair cables will work, but twin individually screened will not. A
lso, if the cable is split or joined other than end-to end, the system will stop
working.
© N.J.D. Electronics 1996 -Page 5-
MDC-128 User Guide
Technical specification.
Dimensions: 482 × 44 × 100 mm
Power supply: 230V AC 50Hz
Power requiremets: 3VA
Mains input: 0.75mm2 cable to BS6500
Fuse: F100mA 5 × 20mm HBC to IEC127.
Midi input: Standard 5-pin DIN
DMX output: 3-pin XLR
Data+ = pin 2 Data- = pin 3 Earth = pin 1
Channels 1-128
Standards:
The MDC-128 complies with the following standards:
EN60065 electrical safety
EN55014 electromagnetic compatibility
IEC 297 fascia panel dimensions
RS-485 Digital transmission system
USITT DMX512:1990 Lighting control protocol
MIDI specification.
-Page 6- © N.J.D. Electronics 1996
© Copyright N.J.D. electronics. Neither the whole nor any part of the information
contained in, nor the product described in thie User Guide may be adapted,
copied, or reproduced in any form except with the prior written approval of N.J.D.
Electronics.
All correspondence should be addressed to:
Customer Support,
N.J.D. Electronics,
10-11, Ascot Industrial Estate,
Sandiacre,
Nottingham,
England.
NG10 5DJ.
Telephone: +44 (0) 115 939 4122
Facsimile: +44 (0) 115 949 0453
Technical Help line: +44 (0) 115 949 0038
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