1.3.1 PRIME Library Description

The PRIME Library contains the MAC layer, the Convergence Layer and the Management Plane as described in the PRIME specification. In a Base Node, it also includes a proprietary Base Management module to handle the interface between the Base Node and the DCU user application and enhance it with additional functionalities.

The user application communicates with the PRIME Library through the PRIME API, which contains the interfaces defined in the PRIME specification as well as stack control functions. The PRIME Library accesses services and drivers in the Harmony 3 ecosystem through the HAL API.

MAC Layer

The Medium Access Control (MAC) layer provides core MAC functionalities of system access, bandwidth allocation, connection establishment/maintenance and topology resolution according to the PRIME specification.

The MAC layer maintains a set of attributes that provide detailed information about its operation. The PIB attributes related to the MAC layer are stored in the MAC PIB storage and the MAC layer provides an interface to access and update their values through the MAC Layer Management Entity (MLME). The PRIME library supports all mandatory MAC PIB attributes as described in the PRIME specification as well as some vendor specific ones.

Convergence Layer

The Convergence Layer (CL) associates the data received from a user application to its proper MAC connection. It is composed by a common part to segment and reassemble packets and service specific sublayers. The PRIME Library implements the Null SSCS and the IEC 61334-4-32 compliant SSCS.

Management Plane

The Management Plane (MNGP) enables a local or remote control entity to perform actions on a node. These actions include providing access to internal parameters defined by PIB attributes as well as managing the firmware upgrade inside the stack.

Node management in the PRIME Library is accomplished through a set of attributes. Attributes are defined for both PHY and MAC layers. The set of these management attributes is called PLC Information Base (PIB). Some attributes are read-only, while others are read-write. The PRIME Library also implements vendor specific PIB attributes to support extra functionalities.

The Management Plane in the Base Node cannot only be used to control the Base Node, but also to access the Management Planes in the Service Nodes and perform actions on them. In order to fulfill both actions, the control entity can access the Management Plane by using the two communication profiles defined in the PRIME specification:
  • PRIME Profile. It is used by the local control entity to perform remote actions on a Service Node. The Base Node receives the requests in the local Management Plane from the Base Management and passes them to the Null SSCS in the CL so that they are sent by PLC to the specific Service Node.
  • Serial Communication Profile. It is implemented as a protocol in the USI Service and is used by the local control entity.

The PRIME certification conformance tests require accessing the PIB attributes and this is achieved via the Management Plane.

Base Management

The Base Management (Base MNG) module is a Microchip proprietary extension over the PRIME specification to increase the functionalities of a Base Node. The PRIME specification does not always define the interfaces between the Base Node and the DCU user application, so new interfaces must be implemented as required. The Base Management handles the Firmware Upgrade Protocol interface and access to the PRIME Profile. It also notifies about network events, such as node registrations and unregistrations, and manages the whitelist.