"Differential download" means that ETS writes only the differences of the current device data to the data known to be already loaded in the device.
There are two flavors of this differential download:
·Differential Download against last state: ETS remembers the data written to the device and loads the differences to this known state. This is available for System B and Mask $0705.
·Differential Download against ex-factory state: (since ETS 5.6) ETS knows the data present in an ex-factory device and loads the differences to this known state. This is also available for Mask $0701.
It is necessary for the second flavor and useful for the first flavor (so that even for the first download into a device, a differential download can be done) to include the ex-factory state (image data and CRCs) in the product data. This is only supported if the target is ETS4/ETS5.
Option 1: Use ETS
·Create a test project, e.g. using the Create ETS test project command
·Open the test project in ETS4/ETS5, move the test device into a line and give it an individual address.
·Load the device
·Export the project again into a knxproj file
·In the MT project, select the Hardware2Program entry and use the Import DifferentialDownload Data command (in Edit > Binary data) to import the knxproj
Option 2: Use an XML file
This option is more flexible. It is based on an XML description of the ex-factory image with associated CRCs.
The XML file may be generated by reading out an ex-factory device using the ExtractExFactoryImage command line tool, or by some other means in the manufacturer's development process.
To import the data,either use the Import DifferentialDownload Data command (in Edit > Binary data), or the MT command line with the diffimport command.
1) Differential Download against last state
2) Differential Download against ex-factory state
3) Differential Download XML
The XML file containing differential download data is structured as follows:
This is the root element of the XML file
Note a schema definition is provided in the file knx_defaultdata.xsd in the MT installation directory. The import function will however also import schema-less XML files.
If present, this element contains the CRCs of the ex-factory device.
If CheckSums/@Type is MCBCRC, this element contains the content of PID_MCB_TABLE for one interface object.
4) ExtractExFactoryImage Tool
ExtractExFactoryImage.exe projectfile [switches]
This command line tool can be used to read out the image data and CRC from a devices relevant for initial differential download.
The individual address of the device to read. If not given, the first device in the project is read
The name of the file to generate (default: projectfile with extension changed to .xml)
The connection string (see Falcon 5.5 SDK documentation) for the Falcon connection to use (default: first USB connection)
Perform a factory reset (MasterReset with erase code 7) before reading.