Lighting Networks 101

DMX

Digital Multiplex Protocolor

ANSI E1.11 – 2004USITT DMX512-A

Asynchronous Serial Data Transmission Standard for Controlling Lighting Equipment

and Accessories

Proper DMX Layout

Console

Fixtureor dimmer

Fixtureor dimmer

Fixtureor dimmer

Daisy Chain the signal path

DMX Troubleshooting

Console

Fixtureor dimmer

“T” or “Y” connections change the cable impedance causing reflection

DMX Mixed Layout

Console

Console

Merger

Opto-splitter/Repeater

Each DMX leg out of a repeater is its own electrical entity

Repeaters can be daisy-chained

DMX Troubleshooting (2)

Console

Fixtureor dimmer

Fixtureor dimmer

Fixtureor dimmer

Signal path must be terminated with 120 ohm resistor

Terminator switch or plugon final fixture

Failure to terminate causes signal reflection back up the cable and intermittent problems

DMX Cable

Low capacitance required to maintain wave form

Belden 9842, 9729, 9829 ProPlex, Showplex Cat5, Cat5e, Cat6 Not microphone cable What they say about barb wire isn’t true

Wave Form

Proper square/digital wave form

Sawtooth wave form – likely caused by capacitance in the cable or slew-rating in the transceiver

Wave form overlay (typically caused by reflection)Multiple overlays are possible

DMX Data Packet

Slot 1(lvl=0)

also 44uS

Start Code

44uS

Slot 2(lvl=0)

Mark-after-break 8uS

Break 88uS

Idle time can follow stop bits

High

1 start bit (low)

2 stop bits (high)

DMX Data FrameLine Idle - high

2 Stop Bits- high

1 Start bit- low

8 Data Bits high or low

1 0 0 1 1 0 1 0

Single Data Frame11 bits altogether44uS transmission time

RDM

Remote Device Managementor

ANSI E1.20 - 2006RDM

Remote Device ManagementOver DMX512-A Networks

Why RDM?

Because DMX isn't enough anymore

Too much gear Too many universes Too much paperwork Too many places for things to go wrong Not easy to fix things on the fly

How RDM Works

Does not make legacy DMX-only gear obsolete

Uses a packet structure, like DMX RDM messages are interleaved or inserted

between regular DMX packets DMX does not need to be present for RDM

messages to be sent Requires all devices be transmitters as well

as receivers

RDM Packet Structure

Start Code

Sub-Start Code

Message Length

Destination UID

Source UID

Transaction #

Port ID/Response Type

Checksum

Message Count

Sub-device

Message Data

Hex CC: indicates RDM Packet

Hex 01: basically for future use

Number of slots used by message

UID of intended recipient

Not sure why: only one controller allowed

Used to match query and response

Identifies controller's sending port and responder's type of messageIncremented by responder – tells controller number of queued msgsIDs device within responder ie dimmer within the rack

Payload! At last!

16-bit checksum of all above fields

RDM Message Block

Command Class

Parameter ID(PID)

Parameter Data Length

Parameter Data

Get, Set or Discovery

i.e.: Network Mgmt, Status, Sensors, DMX512 Set-up, others, or manufacturer specific

Number of slots used by next part of message (can be zero)- responder needs to know when check sum begins

Format depends on the PID

New Rules for System Design

No more than 4 in-line devices between a responder and the controller

In-line devices include opto-splitters, mergers, repeaters, anything that reprocesses the signal

In-line devices must be bi-directional

Timing changes to DMX E1.11 Break time extended to 132uS Each in-line device to reduce break by 22uS

Legacy Equipment

DMX distribution gear developed prior to 2000 will likely need to be replaced

no provision for bi-directional signal end gear will depend on manufacturer

as purchasers you should be demanding support for older gear DMX-over-Ethernet likely will be okay currently no programming consoles with RDM

RDM and Pathway Support for firmware upload over RDM DMX/RDM over Ethernet via Pathport In-line Devices:

DMX Repeater Pro Bi-directional opto-splitter Can also act as a controller

eDIN 1009 RDM opto-splitter Responder Devices:

EDIN 1003 DMX to Contact Output eDIN 1004 DMX-to-Analog eDIN 1006 Analog-to-DMX eDIN 1008 DMX LED Driver

ACN

ANSI E1.17 – 2006Architecture for Control Networks

Remaining Problems

- sheer size of lighting installations (think LED) causing infrastructure problems

- cost of wire and connectors for DMX/RDM

- management tools not covered by RDM- multiple universe management- distribution management (merge,

priority)- everything still mapped to 512

channels

- maybe the answer is... Ethernet?

Ethernet Advantages

- Cheap wiring and distribution gear

- available everywhere

- 10 Mbit = 40 universes at 250 baud(we get back to this one)

- flexibility of star wiring

- cheap (did I mention cheap?)

Proprietary Protocols(again)

Strand ShownetETC Net1ETC Net2

ArtNetPathport

....and less oftenAVAB

CompuliteEnttec

ColornetKiNet

... and none can talk to each other

DMX-over-Ethernet Advantages

signal management - merging, splitting, priority switching

unlimited outputs (dependent on network architecture)

up to 128 universes of input (typical 2008)

number of fully active universes varies from protocol to protocol but typically 12 - 15

Ethernet Limitations

finicky installations

sensitive to electrical interference

not robust (compared to Belden/XLR)

100m cable runs versus 500m for DMX

Enter ACN

media agnostic – use whatever cable you want

intended as a generic language to control devices

allows for plug and play

Alphabet Soup (1)

CID – Component IDentifier

DDL – Device Description Language

DMP – Device Management Protocol

SDT – Session Data Transport

RLP – Root Layer Protocol

Three letter acronyms – not just for audio anymore

Alphabet Soup (2)

CID – Component IDentifier - unique identifier for each device on system

DDL – Device Description Language

- an XML file describing device properties and associated ‘behaviours’

- controller can pick and choose what it wants depending on sophistication and need

Alphabet Soup (3)

DMP – Device Management Protocol

- how to get and set properties of the device

SDT – Session Data Transport

- heart of ACN

- allows efficient, reliable (error-checking) data transmission to one, a few or all devices on the network, depending on need

- created specifically with the typically assymmetric lighting data flow in mind

ACN Overview

- information not bound by 512 data slots

- formatted or configured according to need- device reports native resolution

- end devices can report abilities, parameters to the controller - no searching for libraries anymore

- configuration using terms that make sense to the user

- devices not limited to lighting equipment

How Will it Fit Together?

- Ethernet backbone carrying ACN signals

- some devices such as media servers, dimmer banks and LED drivers will sit natively on the network

- gateway nodes will provide ACN-RDM control over configurable devices

- gateway nodes will provide ACN-DMX control over legacy and 'dumb' gear

What’s on the shelf now?

- DMX, obviously

- RDM, increasingly

- streaming ACN Ethernet protocol is available as Net3 (ETC), sACN (Pathway) and soon others (MA Lighting, Pharos)

- in the near term (5 years or less) sACN will replace the proprietary protocols

- openACN group working on open source code modules (www.openacn.org)

Ethernet Design Tips (1)

- structured wiring- IDC termination- TIA/EIA-568 certification

- Cat5e vs Cat6-STP and conduit

- observe cable lengths- max 90m for copper

- copper versus fibre

Ethernet Design Tips (2)

- Power-over-Ethernet (802.3af)

- device classes and sufficient power

- switches vs routers

- current lack of Etherner protocol converters

Troubleshooting (1)

- managed vs unmanaged switches

- bad things, maybe:

- broadcast storm control- IGMP packet sniffing- multicast filtering- spanning tree protocol

Troubleshooting (2)

- maximum traffic for 10Mb devices- 24 universes for broadcast

protocols- traffic patterns

- Ethernet component reliability issues

- RJ45 vs Ethercon vs XLR

- segregated traffic-VLANS

- media converters