About DMX512
DMX512 is an industry standard for controlling dimmer packs (and many other devices) using a high speed RS485 serial port. Dimmer packs are used to control room lighting and are widely available. Dimmer packs come in many different styles. They simply plug into a wall outlet and you plug the loads (lights or other line operated items) into the outlets provided. They also come in a form to be mounted into a wall mounted enclosure and are interfaced to the lighting in various ways. If you have a 'theater' style room or kiosk, and want to control the 'mood lighting', use this DMX feature to fade the lights off, start your video, then fade the lights to on. Some of my boards with DMX have a optional 3 pin Molex header. You can make your own DMX cable, order cables from the web. HMS no longer stocks DMX cables!
HMS DMX512 Receiver (HMS-485x: This new interface board for the Brightsign 'Compacts' lets a DMX controller run the Brightsign. I.E. A typical 'show' such as a 'rock concert' has lots of lighting and special effects. This portion of the 'show' is controlled via a DMX512 controller. The master controller is either a computer with a DMX output device, or a DMX controller that has been programmed to run the lights show. Now the Brightsign can become one of the devices controlled by the DMX controller.
DMX512 Receivers: DMX 'Light Boxes' or Fixtures have a dip switch to set the channel. The range is channel 1 to channel 511. The fixture then waits for the sync byte and then starts counting the bytes. When the byte count matches the channel (fixture address) then the bytes are recorded. If a 4 channel device, then the 4 bytes transmitted (including the address and 3 successive byte) then the fixture records those bytes and sets the outputs according to the data of the bytes (range is 0 to 255 for the bytes)oncert' has lots of lighting and special effects. This portion of the 'show' is controlled via a DMX512 controller. The master controller is either a computer with a DMX output device, or a DMX controller that has been programmed to run the lights show. Now the Brightsign can become one of the devices controlled by the DMX controller.
The DMX512 standard is 'Break' signal, then send a zero byte, then send byte 1 for channel 1, byte 2 for channel 2 and so on. The 'Break and the 'Zero byte' (it is called the sync byte in the standard), sets the DMX512 receivers to start over on counting bytes. When the DMX512 gets the byte that matches its address (address 1 to 511), then that byte is 'captured' by the receiver. DMX512 receivers normally have some way of setting their starting address. Then if that receiver has 16 channels, the next 15 bytes after it's 'address' are also captured by that receiver and output to its ports. If the DMX device is a dimmer pack, then the lights will light according to the value of the data byte held by that channel.
DMX dimmer pack light values: A value of zero to a channel turns that channel off. A value of 255 (all 8 bit high) sets the channel to full on. A value of 1 sets the chanel to 1/255 of on brightness, and so on.
About Fade: Fade is a dimming 'rate' feature. The target brightness is adjusted at a 'fade rate'. Fade values are in milliseconds. Fade values less than 12 (60 Hz) may cause intermittent fade on most dimmer packs. Also, the more channels that are sent, takes more time to send the DMX bytes. More time (sending channels) means that fade won't be as smooth or as quick. You may have to experiment with fade values to get the smooth stepping of brightness. Incandescent bulbs won't start glowing with a value less than 40. So if you want fade to start 'instantly' try setting the brightness to 40 with a fade value of 0 (instant change). Pause for 20 milliseconds so that the dimmer box can set it's timer to 40, then send another fade command to increase to the target value with fade value of 12 or greater. Dimmer Packs that are intended for LED lighting may use PWM (Pulse Width Modulation) for controlling the power. The fade value for PWM DMX boxes may not have a limitation on the fade for these style dimmer packs.
Brightsign Values: Because all 'Btn's' on the Brightsign I/O are normally high, the 'HMS DMX512 Receiver' will normally invert the byte received via DMX512. This feature can be cancelled by selection on the option header. This way, when a value of zero is sent the Brightsign, all Btn's (Btn0-Btn7) remain high. This is the default state of the buttons. When a value of '1' is sent to the Brightsign, then Btn0 is set low.
To set a Btn low, use this table:
Add any decimal numbers together to set more than 1 'Btn' low. I.E. to set Btn0 and Btn7 low, add 1 and 128 to get 129. Send 129 to the Brightsign via DMX and Btn0 and Btn7 will go low.
Note: If the 'Don't invert DMX byte' is selected on the options header, then a zero sent by the DMX512 controller will be output as a zero to the Brightsign (all Btn's low).
You can create 'lighting scenes' and then put the scenes file on the SD card. Using BrightScript, you can then get load the file from the SD card and decode it during a video playback or, for a slide show. Contact the people at BrightSign to get help with this programming.
Demo
Video (90 mega bytes)
Note: Custom software available to meet your special lighting requirement. I.E. if you have an information kiosk with a demo video, I can 'time' lighting events with your playback. Any number of DMX channels can be programmed per your requirement.
Updated: March 31, 2023