Data Link Layer

Abstract

The data link layer provides the reliable means to transfer data between network nodes by detecting and possibly correcting errors that may occur in the physical layer. This layer has the important task of creating and managing data frames. There are usually two sublayers, Logical Link Control (LLC) layer and Medium Access Control (MAC) layer. LLC layer defines the service to the network layer and MAC defines how the communication medium is accessed by multiple nodes. This chapter lists the services that the WirelessHART data link layer provides to the upper network layer. It further describes in more detail the LLC and MAC layers. We describe the message format and its flow control, error detection, and security. We also describe how to maintain slot synchronization with TDMA, schedule slots to listen for packets from neighbors and propagate packets from the network layer. Please refer to the TDMA Data Link Layer Specification (HCF_SPEC-75) for more details.