Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

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5.1.2. EMAC Use Cases

Time Sensitive Networking (TSN) provides capabilities in addition to the standard Ethernet protocol, to transfer accurate time between locations and to get time-sensitive packets to their destination in a timely manner without interference by lower priority traffic.

The ability to transfer time is done by implementing the IEEE 1588-2008 Advanced Timestamp. To get the time-sensitive packets to their destination quickly is done through two capabilities:
  1. IEEE 802.1Qbu – the ability to interfere in the middle of a packet, interrupt it's transmission, send a priority packet, and then resume transmission of the original packet.
  2. IEEE 802.1Qbv - the ability to define traffic classes and prioritization, and appropriately shape the traffic based on these prioritization.

TSN is typically used at the lower end of Ethernet speeds. At 100 Mbps, a 9 KB jumbo frame would take 720 us. Therefore, if you have a high-priority packet that needs to be sent immediately after a jumbo frame begins, you need to wait at least 720 us at 100 Mbps, which creates a desire to interrupt this packet. At 100 Gbps, this would be reduced to 720 ps, dramatically reducing the time penalty for just waiting until the packet is complete. The HPS supports 3 EMACs with TSN capability, with configurable choices of RGMII single-ended pin connection at rates of 10/100/1000Mbps or connecting through soft logic to a regular serdes for SGMII interface with rates up to 2.5 Gbps.

Industrial applications are one of the major use cases for the Agilex™ 5 EMAC TSN. The primary application is to act as a programmed logic controller (PLC) and programmable automation controllers (PAC). PLCs play a critical role in industrial automation and are part of the operational (OT) control functions in a typical tiered industrial automation infrastructure. The International Society of Automation’s ISA-95 model, a standard for integrating enterprise and production control systems, comprises four levels as illustrated in the figure below.

Figure 49. Typical TSN application in an ISA-95 Model Topology

Agilex™ 5 is designed to support back-to-back connections and a star topology with the TSN switch, and act as an end point for Industrial automation. It is targeted for device application levels 1, 2 and 3 as illustrated in the ISA-95 model above.

For example in a modern industrial factory floor, there may be requirements to time synchronize the entire factory to the same sense of time to allow for appropriate synchronization of activities. In addition, there may be the need for priority traffic, to send safety shut-down messages, or for low-latency control loops.

In a typical use case, PLC/PAC are used for control functions of level 1 and level 2 and require at least 2 EMAC TSN ports for control loops. For example, one TSN port for remote IO where the DUT is connected at a factory cell level and another TSN port is connected as a control loop to daisy-chain other PLC/PAC systems (level 1) for production or product line control, as illustrated at the level 2 layer in the ISA-95 model. The remaining TSN ports can be used for connecting to a SCADA system (level 3) or another control loop depending on the user requirements. Each TSN port can be connected to a separate TSN sub-net with different time reference.

In general, industrial applications for FPGA SoC devices include:
  • Programmable logic controllers (complete device or I/O expansion for external CPU)
  • Single and multi-axis drive systems
  • I/O modules/bus couplers
  • Networking bridges
  • Industrial Ethernet programmable NIC
  • Industrial gateway with control and analytics
  • Industrial camera interfaces
Note: Daisy chain and bridging features require custom software solutions and are not enabled by default.