6. Changes between versions

This document tracks the various additions and breaking changes made in the different versions of the SECoP specification.

Minor version updates like 1.0 → 1.1 only contain backwards compatible changes, while major version updates can contain breaking changes.

A SEC node typically only implements one version of the specification. To maximize compatibility, all clients should strive to support all existing major versions.

6.1. Version 2.0

This version is in the process of being finalized.

Breaking changes

These changes make a 2.0 client necessary to connect to a 2.0 node without major loss of functionality.

• The format of the *IDN? reply has been slightly changed and the meaning of the third field is now clarified.

• The visibility property for modules and accessibles has a new format with extended possibilities (SECoP Issue 079 hints for readonly access).

• The meaning property for modules has a different format with capabilities to link to external definitions/ontologies. meaning can now also be given for individual accessibles, and new “functions” have been added.

• The HasOffset feature has been removed; instead, only the offset parameter is now specified with different semantics: the node needs to take the offset into account when processing target and value. The client can inspect and potentially change the offset, but does not need to apply offset to target and value to get a corrected value.

Backwards compatible changes

• The specification text has been generally restructured and edited to improve clarity and presentation.

• The optional check/checked messages have been added, as well as the checkable accessible property (SECoP Issue 075 New messages check and checked).

• The matrix data type has been specified for datainfo.

• The AcquisitionController, AcquisitionChannel and Acquisition interface classes have been specified (RFC 106: Acquisition interface classes).

• The UDP discovery protocol has been specified (RFC 105: UDP discovery for SECoP).

• Optional SECoP transport over WebSockets has been specified (RFC 107: Optional WebSocket support).

• Predefined parameter postfixes have been specified to allow enabling/disabling parameters and specifying dynamic limits (SECoP Issue 077 predefined parameter name prefixes). The previously explicitly defined target_limits parameter follows this _limits postfix pattern.

6.2. Version 1.1

This minor revision was released in 2025 and is available in the repository.

• The implementation property of modules has been added (SECoP Issue 061 new predefined property implementation).

• The controlled_by and control_active optional parameters have been specified, as well as the control_off command (SECoP Issue 065 handling of coupled modules).

• Features have been defined as a type of base class, and the features module property has been added (SECoP Issue 072 features).

• The target_limits parameter has been specified (SECoP Issue 073 HasLimits and HasOffset).

• The HasOffset feature and the offset parameter have been specified (SECoP Issue 073 HasLimits and HasOffset).

6.3. Version 1.0

This is the first published version of the specification released in 2019. It is available in the repository.

Various pre-release candidates have been preserved as well.