Bringing Ethernet to the Plant Floor? Seven critical things to know before you do it.
1. Do not to take Office topologies to the plant floor but implement plant/machine topologies with Ethernet.
Office Ethernet infrastructures are typically based on commercial grade products meant to be located in a temperature controlled environment and Ethernet switches designed around a large star topology. On the other hand, Industrial Ethernet architectures take into account the differences in conditions and additional feature requirements such as high speed and redundancy. An Industrial network utilizes different topologies dependent on the plant environment (star, ring, tree, and/or line). Shielded cables, metal connectors, and devices with higher temperature and vibration specifications are also required.
2. Ethernet is just the wire; you need an industrial protocol to run automation applications.
The EEE 802.3 Ethernet Standard defines the wiring, the media access rules, and the structure of a frame. Although different devices utilizing communications based on this standard can coexist on the same network, the devices must utilize the same protocol or “communication language” in order to communicate with each other. PROFINET is a communication protocol for industrial applications. It provides full functionality for Distributed IO, Machine-to-Machine connectivity, Machine Safety, and Motion Control.
3. Speed and determinism are crucial.
Throughput is the crucial factor when determining the speed of the network. PROFINET achieves maximum throughput in a network designed for the plant floor with deterministic and reliable communication. The turnaround times in the PROFINET stack are more than 10 times faster than a standard Ethernet TCP/UDP implementation. PROFINET accomplishes this feat by taking advantage of a Real-time channel for time-critical applications where speed and determinism are required and while using the Standard TCP/IP channel for configuration, diagnostics, network routing and other non-time critical tasks.
4. Network configuration may include programming (but hopefully not!).
When establishing the communication relationships between devices, PROFINET utilizes a configuration approach instead of a programming approach. Due to the object-oriented approach which configures interconnections between devices instead of programming and debugging communications, system-integrators and end-users confirm a reduction of 25% in engineering time and commissioning. One key factor for this improvement is the ability of the PROFINET configuration tools to automatically calculate network utilization to specify the system-wide scan rate.
5. Your Industrial Ethernet should not only work today but should be future proof.
PROFINET allows customers to implement a totally integrated automation solution at their own pace on one single Ethernet network which supports the different control disciplines (peer-to-peer communications, distributed IO, machine safety, motion control, and data acquisition.) PROFlNET can also handle the requirements of vertical integration. One example is the trend to seamlessly integrate production data to the business systems (like Enterprise Resource Planning systems). Users can gather production yields, metrics, and other productivity measures with direct connectivity to the plant floor.
6. Your Industrial Ethernet should integrate with already implemented networks and machines from different vendors.
Since PROFINET works with standard Ethernet switches and utilizes the TCP/IP protocol suite, a system based on PROFINET can connect to the overall automation network without the requirement of high-end switches or special features such as IGMP snooping and VLAN. PROFINET not only allows network connectivity but also allows communication between multiple vendors’ products and systems.
7. Account for the cost of engineering, installation, and maintenance.
PROFINET and Industrial Ethernet components take advantage of IT technologies to monitor and display the status of the network. For example OPC and SNMP. Furthermore, diagnostic capabilities within PROFINET provide the ability to incorporate the status of the network directly into the automation system, including PLC, SCADA, and HMI systems. This simplifies configuration and troubleshooting by allowing everything to be done from one central location.
Adapted from material provided by Siemens.
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