german:  |
DMX Interface Hardware: this is a complete step-by-step description how to access the hardware, and how to set the working parameters required for DMX512/1990. Find memory maps, hardware addresses and other hardware-related stuff.
|
THE PMX PROTOCOL
I will describe PMX in depth as this protocol is very popular and versatile, and many people use is to control Golden Scans and Universal Interfaces via a computer COM port! so here goes.
This provides information for people wishing to receive serial data from pulsar and Clay Paky controllers or to drive Pulsar and Clay Paky lighting aquipment.
SERIAL FORMAT
9600 baud, 1 start bit, 8 data bits, 1 stop bit, no parity. The data stream may be fully packed.
CABLE
For RS432 operation, use 2 core screenedcable. Screen=Chassis Ground - connect at both ends, Cores: Signal, Signal Ground (which must NOT connect to the screen or chassis). For RS232 operation, over shorter distances, for example from the Masterpiece to the Screen Driver, single core screened cable may be used.
MAXIMUM LENGTH RS423 1200m, RS232 100m.
TERMINATION
line termination is NOT required.
BRANCHING
no problem.
HANDSHAKING
not required - so RTS (Pin E or 5 on a BBC Micro or pin 4 on a 25 pin `D' connector) and CTS (Pin D or 2 on a BBC Micro or pin 5 on a 25 pin `D' connector) need to be cross linked at the computer.
RESOLUTION
up to 14 bits possible, but normally 8 bits (256 possibilities), older products used 7 bits (128 possibilities).
NO OF CHANNELS
15,360 max. The protocol allows 128 pages of 120 channels each for future expansion!
REFRESH
is not required. Data is latched by the receiving device. Only the changes need to be transmitted. However it is good practice to send the constant Levels and the Page Number from time to time- for example, when there are no changes to send.
TRANSMISSION PROTOCOL:
Address
A byte with bit 7 set is an Address i.e. a Channel Number.
Channels Numbers in the range 1-120 are sent as 128-247.
Channels Numbers in the range 121-240 are sent as 128-247 after having first changed the Page Number from 0 to 1 see below.
Level
A byte with bit 7 clear is a Level. ONE or TWO Level bytes with values of 0-127 follow an Address.
For 7 bit resolution, only ONE byte need be sent.
For 8 bit resolution, where bit 0 is Lo, only ONE byte need be sent.
For 8 bit resolution, where bit 0 is Hi TWO bytes need to be sent with bit 6 of the second byte set. For future expansion, bit 5 to bit 0 of the second byte could be used, giving up to 14 bit resolution. If only ONE Level byte is sent, it will not be acted upon until the next Address is received.
Bytes 248 to 255 are used for special codes:
248 sets all channels to the Level which follows e.g. 0 for Blackout.
249 changes Page Number to the ONE Level byte which follows (0-127).
Each of the 128 possible pages allow you to address 120 channels. Receiving units default to page 0 (channels 1-120) at switch on. The Page Number remains in the new page until another 249 sequence is sent. 250-255 are reserved by Pulsar to send ASCII, Key Presses, Slider Moves & other Controller to Controller information.
If you need further information I would be only to pleased to answer any of your questions. Pleas address all correspondence to me at
steve@cpp.com
for work or
steve@histon.demon.co.uk for home.
Pleas Note - Everything contained within these web pages are MY views and not necessarily the views of Pulsar, Clay Paky, Esta, the Wife, Kids, Uncle Tom Cobbley or anybody else! - Thank You
MORE INFO ON DMX EQUIPMENT:
 DMX-Tester |
Measuring and Testing Equipment for Lab and Road Use |
| Interfaces |
DMX/Analog Decoder, Relay- and Dimmer-cards |
| LIGHTLINE |
SOUNDLIGHT DMX Glassfiber Technology |
