This article covers the following topics:
With this app it is possible to compare devices from an ETS project with their physical representatives in the actual KNX installation. In this way individual devices, entire lines and/or areas (or even the entire ETS project) can be compared. The most important use case is to check for functional differences (e.g. due to manipulation/changes by third parties) in the installation, e.g. in the event of a warranty claim. Another use case is to make sure that required modifications have been accomplished, e.g. in the context of a security related upgrade.
Which devices can be compared?
In principle, any registered/certified device with at least one Application Program 'onboard' can be compared, i.e. a KNX choke or a KNX connector cannot be compared. There is however one exception: devices with a 'multi-pass' plug-in cannot be compared at all.
After a device has been commissioned by ETS, all its required configuration data, which is called the 'memory image' (or short the 'image') is downloaded into device memory. This app has the functionality onboard for reading back the memory images from devices (i.e. to reconstruct the 'memory image'), for which it uses a two-step process:
- Step 1 - Basic Comparison
- Step 2 - Enhanced Comparison
Step 1 - Basic Comparison
The following information is read-out from the physical device in the installation and compared with the device in the ETS project:
- its Mask Version (also known as 'device descriptor')
- the ID of the currently loaded Application Program
- the Load Status of the currently loaded Application Program
If the basic comparison fails, the enhanced comparison will not be performed. The basic comparison fails when:
- the Mask Version is unknown to ETS.
- the Mask Version does not match or is not in the compatibility list.
- the Application Program ID does not match, i.e. the combination Manufacturer ID + Device Type + Device Version does not match.
- the Load Status of the Application Program is set to 'Not loaded'.
If a device has more than one Application Program, then this applies for all Application Programs.
Step 2 - Enhanced Comparison
The app creates two memory images, one based on the information found in the ETS project and the other based on the information read from the physical device. The app then compares both memory images and generates a list with differences (if any).
A difference does however not necessarily imply a functional change and/or manipulation of the device.
Example: A scene default value loaded via ETS, could afterwards be modified by the user (during runtime), which has to be considered as an 'allowed' manipulation.
Follow these instructions in order to activate the app:
- Purchase a license from MyKNX
- License it as explained here
- No additional *.etsapp file needs to be installed
Use of the Device Compare app in ETS
The function can be invoked via the context menu from one or multiple devices. Since this app reads out data via the bus, using it will result in operations being displayed in the sidebar (one per device).
Differences found are shown in the Results Display per device.
With the button Update Programming State it is possible to make the physical device in the installation match again with the device in the project.
Note: This button will affect all devices in the list.
Note about the download flags (in the ETS project):
- the app resets (if necessary) the respective download flags in case of a mismatch between the physical device and the device in the ETS project.
- the app sets (if necessary) the respective download flags in case of a match between the physical device and the device in the ETS project.
In summary, there are three different results possible for a device in a project after the comparison:
- the result can be evaluated: displayed in green or red.
- the result cannot be evaluated: displayed in yellow.
- no result because the device cannot or even should not be compared. (raised as warning)