ADVANTECH has written about the application of Ethernet in high availability manufacturing.
Modern manufacturing is focused on reducing complexity and increasing the transparency of processes throughout the enterprise.
The ability to communicate data from any part of the enterprise is a key factor in this drive.
The traditional Purdue Reference Model for computer integrated manufacturing has been compressed to the three layers of plant floor, manufacturing operations management (MOM) and the manufacturing/enterprise business system.
On the plant floor, field devices and machines, controllers, higher level control systems and distributed control systems communicate with each other.
The MOM layer is required to have instantaneous communications with asset management, production control and production management.
In some cases, if communications between the systems or devices are lost, production can be severely disrupted. Non-stop communications are therefore a critical part of modern manufacturing.
Earlier in the history of industrial computing, serial interfaces such as RS-232 were used commonly in devices such as programmable logic controllers (PLCs). These interfaces had connectivity and physical limitations, and were not scalable to cover the entire factory floor.
Additionally, custom application program interfaces (APIs) were required for every device-to-device transmission, and small changes could break the communications method.
Yet asynchronous serial communications connections are still among the most commonly used industrial device interfaces. They are used for configuration and setup, human-machine interfacing (HMI), production setup, monitoring, troubleshooting and diagnostics.
To overcome the limitations of the legacy system while preserving the use of serial technology, an Ethernet serial device server can be used. The server operates as a portal which acquires serial data, then routes it through the Ethernet network, allowing both new applications and old devices to be used in parallel.
Ethernet bypasses the distance and interface limitations of serial devices. It allows the use of servers and gateways to build a network. In the event of an interruption of communications links a redundant link can be installed and operated. Dual and independent network connections will provide protection against single-point failures, ensuring continuous uptime.
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