The DMX512 protocol (Digital MultipleX) is a standard for networks that are used to control stage lighting and effects. It is the standard way for connecting controllers (e.g. lighting consoles) to dimmers and special effects like e.g. smoke machines and intelligent lights. The number 512 refers to the 512 control channels that the protocol can handle.
The DMX512 decoder I/O decodes analog signals to DMX512 messages. The DMX512 decoder has auto level detection and auto hysteresis detection. The output of the DMX512 decoder I/O can be shown in a Table sink or passed on a to a Value extractor I/O.
The following fields are extracted from the DMX512 communication and shown as a column in the table:
| Field name | Purpose | Default shown |
|---|---|---|
| Start code (Dec) | ||
| Start code (Hex) | ||
| Slots (Hex) | ||
| Slots (Dec) | ||
| Flags | ||
| Valid | Validity of the message |
Additionally, many other fields can be extracted from the DMX512 communication. These are specific fields, which can be used with certain sensors. Refer to the documentation of the sensor to find out which fields are useful to place in the table.
To show or hide specific columns from the table, use the Select columns
(
) button
in the Table sink.
Double clicking a row in the table will zoom the active graph in to the time frame corresponding to the table row.
The Value extractor I/O can be used to extract a specific value from the decoded data and present that in a graph, a meter or a table.
Measurement on a DMX512 bus, with data decoded by a DMX512 decoder.
DMX512 decoder properties
To control the behavior of the DMX512 decoder I/O, several properties and actions are available.
These can be accessed through a popup menu which is shown when the I/O is right clicked in the Object screen.
The properties can also be accessed through its settings window which is shown when the I/O is double clicked in the Object screen.
To open the Object screen, click the 
Show object screen button.
By default, the settings window only shows the most used settings. When Advanced is ticked, the extended window with all settings is shown. See also the program settings.
Level
In order to decode the analog signal into a digital signal, the DMX512 decoder I/O compares the analog input signal with a mid level: anything above that level is considered "high" and anything below that level is considered "low".
Hysteresis
To minimize the effect of noise on the signal when comparing the signal to the level, a Hysteresis can be used around that level. Anything above "level + hysteresis/2" is considered "high" and anything below "level - hysteresis/2" is considered "low".
Auto detect Level / Hysteresis
Enabling Auto detect Level / Hysteresis will let the software determine a suitable Level and Hysteresis, based on the measured signal. Each time new data is available, the suitable Level and Hysteresis will be determined again. In streaming mode, the Level and Hysteresis are determined once based on the first chunk of data and remain at these values though out the whole measurement.
Auto detect Level / Hysteresis is default disabled.
Invert
For correct detection, the Invert property must be set to the correct value, corresponding to the bus that is under measurement.
- When Invert is disabled levels above high level are logic 1, levels below low level are logic 0
- When Invert is enabled levels above high level are logic 0, levels below low level are logic 1
Invert is default off.
Common properties and actions
Related information
Pulse decoder
The Pulse decoder I/O decodes the two signals from a quadrature encoder to a pulse count/position.
I2C decoder
The I2C decoder I/O decodes analog data on the SDA and SCL lines of an I2C bus to I2C data.
UART / Serial decoder
The UART / Serial decoder I/O decodes analog data on a UART, RS232, RS485, MIDI, DMX, LIN or other compatible serial bus to serial data.
CAN decoder
The CAN decoder I/O decodes analog data to CAN data.
J1939 decoder
The J1939 decoder I/O extracts SAE J1939 SPN values from CAN messages.
SPI decoder
The SPI decoder I/O decodes analog data on an SPI bus to SPI data.
LIN decoder
The LIN decoder I/O decodes analog data on a Local Interconnect Network bus to LIN message data.
SENT decoder
The SENT decoder I/O decodes analog signals on a SENT bus to SAE J2716 SENT messages.
FlexRay decoder
The FlexRay decoder I/O decodes analog data on a bus to FlexRay message data.
Value extractor
The Value extractor I/O extracts a specific value from a decoded serial communication and makes it available for graphs, meters and tables.
