The Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a sublayer of the Data Link Layer specified in the seven-layer OSI model (layer 2), and in the four-layer TCP/IP model (layer 1). It provides addressing and channel access control mechanisms that make it possible for several terminals or network nodes to communicate within a multiple access network that incorporates a shared medium, e.g. Ethernet. The hardware that implements the MAC is referred to as a Medium Access Controller.The MAC sub-layer acts as an interface between the Logical Link Control (LLC) sublayer and the network’s physical layer. The MAC layer emulates a full-duplex logical communication channel in a multi-point network. This channel may provide unicast, multicast or broadcast communication service.
10/100 Ethernet MAC
- Implements the full 802.3 specification with preamble/start frame delimiter (SFD) generation, frame padding generation, cyclic redundancy code (CRC) generation, and checking on transmit and receive respectively
- Supports 10-Mbps and 100-Mbps operation
- Supports full-duplex or half-duplex operation selectable via a core configuration option
- Seamless interface to commercial fast Ethernet PHY device via a 4-bit Medium Independent Interface (MII) operating at 25 MHz
- 32-Bit Avalon™ streaming bus system-on-a-chip (SOC) interfaces allow for efficient direct memory access (DMA) transactions
- 32-Bit Avalon System Interface with separate slave ports for data and control
- CRC-32 checking at full speed with optional forwarding of the frame check sequence (FCS) field to the user application
- CRC-32 generation and append on transmit or forwarding of user application provided FCS selectable on a per-frame basis
- Programmable frame maximum length providing support for any standard or proprietary frame length (e.g., 9-Kbyte jumbo frames)
- Statistics indicators for frame traffic as well as errors (alignment, CRC, length) and pause frames providing for IEEE 802.3 basic and mandatory Management Information Database (MIB) package as well as Ethernet MIB (RFC 2665) and Remote Network Monitoring (RFC 2819) enabling implementation in simple network management protocol (SNMP) environments
- Includes data path first-in first-out (FIFO) interfaces with fully programmable depth and threshold levels ensuring data rates of 1Gbps with full back-to-back frame transfer support
- MDIO Master interface for PHY device configuration and management with two programmable MDIO base addresses
- Media access controller (MAC) fully integrated in Altera’s SOPC Builder with supporting files for easy system configuration and generation
- C Software drivers, example applications, and driver for TCP/IP networking libraries
Figure 1 shows MorethanIP’s 10/100 Ethernet MAC Core.
10/100 Ethernet Media Access Controller Core
The programmable 10/100 Ethernet MAC from MorethanIP provides, with a single intellectual property (IP) core solution, a solution for Ethernet applications (line card, network interface card (NIC), or switching) operating at 10 or 100 Mbps. The 10/100 MAC core can operate in half- or full-duplex mode, supports transparent (for switching applications) and full Ethernet frame termination/generation (for NIC or line cards applications).
The core can seamlessly connect to any industry standard PHY with Media Independent Interface (MII) and to a user application via the Avalon SOC interface available, for example, with Nios® embedded processor environments. Optionally, the core is also available with a generic FIFO interface (Atlantic™ interface compatible).
The core is optionally delivered in generic synthesizable hardware description language (HDL) code, or as a FPGA netlist. In addition, MorethanIP also provides a programmable 10/100/1000 Ethernet MAC core.
The MAC comes integrated in Altera’s SOPC Builder for easy system configuration and generation and drivers are provided to use the MAC with networking libraries.
1) EtherNet/IP is an application layer protocol that is transferred inside a TCP/IP Packet. That means that EtherNet/IP is simply the way data is organized in a TCP or UDP packet. For information on what TCP or UDP is get my Industrial Ethernet Book.
2) All devices on an EtherNet/IP network present their data to the network as a series of data values called attributes grouped with other similar data values into sets of attributes called Objects.
3) There are EtherNet/IP Required Objects – Identity, TCP, Router that every device must have. The EtherNet/IP Specification defines those objects.
4) There are EtherNet/IP Application Objects that have the data for your specific device. For example, an EtherNet/IP Drive device has a Motor Object. EtherNet/IP devices that support specific devices all have the same set of EtherNet/IP application objects.
5) There are two kinds of messages that are transferred between an EtherNet/IP Scanner Device (opens connections and initiates data transfers) and EtherNet/IP Adapter devices (provides data to Scanners). These messages are Explicit Messages (asynchronous, as needed) and I/O Messages (Data messages that are continuously transferred).
6) EtherNet/IP is part of CIP, the Common Industrial Protocol. CIP defines the Object structure and specifies the message transfer. CIP protocol over CAN is DeviceNet. CIP protocol over Ethernet is EtherNet/IP.
Ethernet/IP (Ethernet Industrial Protocol)
Ethernet/IP (Ethernet Industrial Protocol) is a network communication standard capable of handling large amounts of data at speeds of 10 Mbps or 100 Mbps, and at up to 1500 bytes per packet. The specification uses an open protocol at the application layer. It is especially popular for control applications.
Ethernet/IP typically employs active star network technology. This type of network is easy to set up, operate, maintain, and expand. It allows mixing of 10 Mbps and 100 Mbps products, and is compatible with most Ethernet switches. Ethernet/IP is used with personal computers, mainframes, robots, input/output (I/O) devices and adapters, programmable logic controllers (PLCs), and other devices. The specification is supported by the Industrial Ethernet Association(IEA), ControlNet International (CI), and the Open DeviceNet Vendor Association (ODVA).