In this document, the different upgrade scenarios, and the support for each of them will be outlined.
As a general rule, major versions may only be upgraded, never downgraded, while minor versions within the same major may be up/downgraded at will.
Please read: How do I upgrade the software?
The following scenarios go into specifics.
1. Note on the version number
The version number is split into four parts; [Major].[Minor].[Type].[Revision] like 1.3.1.r66
2. Scenario 1: an old controller with new endpoint - not supported
A system with a controller at [Major] < endpoint [Major] is not supported. This has the consequence that in order to add additional endpoints to an existing installation, which is running at a noncurrent software version, the software version must be bumped to at least the same major version as the endpoint.
An installation with a controller and endpoints, at version 1.3.1.r66 needs to add three new endpoints. The endpoints are delivered in version 2.0.0.r66. The endpoints may be connected to the system, but will never come online nor be downgradable. The entire system must be upgraded to at least version 2.0.0.rxx.
3. Scenario 2: a new controller with old endpoint - supported
A system with a controller at [Major] >= endpoint [Major] is supported. This means that you can freely use any older endpoints with an updated controller.
An installation with a controller and endpoints, at version 2.0.0.r66 needs to add three new endpoints. The endpoints are running version 1.0.1.r59 because they were bought several years ago. The endpoints are automatically upgraded when they are added to the system.
4. Scenario 3: new controller downgrade major - not supported
A controller may never be downgraded to a previous major version.
5 Scenario 4: new controller downgrade minor - supported (but not encouraged)
Downgrades within between minor versions are supported, as long as they are in the same major version. It is not encouraged to do so, as the test coverage for downgrades between any two versions will inherently be low.