Industrial Ethernet Guide - Real-Time Works Only In A Box
The following is part of A Comprehensible Guide to Industrial Ethernet by Wilfried Voss.
Ages-old technology wisdom says that real-time works only in a box. This statement has, however, been obsoleted by Industrial Ethernet. Industrial Ethernet allows the design of a real-time network rather than an isolated real-time system.
Note: The reference to real-time capabilities of Industrial Ethernet is intended as a general view of the technology. There are still lively discussions between the various user organizations about the degree of “real” real-time performances of their respective technologies.
Let’s look back at a previous statement:
"While there are compelling reasons to prefer Distributed Control, Central Control is traditionally better suited for real-time control."
When it comes to real-time control of high-speed and high-precision manufacturing equipment (such as, for instance, a robotic arm), it is mandatory that all electrical components work together in a highly synchronized fashion. The sampling of measurements at non-deterministic or even random times will deliver incorrect results.
Execution speed is sometimes important while determinacy is always important.
The challenge for all serial networking solutions lies in the guarantee of deterministic behavior, which is represented through constant cycle times, low latency, and minimal variations (jitter). Some of the traditional protocols (e.g., CANopen or DeviceNet) have mechanisms included to support real-time control through, for instance, synchronizing nodes, but they reach their limitations reasonably quickly and may become unpredictable, especially with the demand for short cycle times.
The only solution thus far has been to abandon the idea of distributed control and instead rely on central control, because only an enclosed processor system, due to its compact design, could guarantee short cycle times with low jitter.
Here, too, Industrial Ethernet plays a unique role due to its vast speed. The implementation of unique real-time software add-ons on top of or bypassing the TCP/IP protocol suite and the application of Ethernet switches allow a broad range of real-time applications through distributed control.
The highly deterministic real-time performance of Industrial Ethernet with short cycle times and low jitter is unsurpassed by any other Fieldbus technology.
netSHIELD"NSHIELD 52-RE" - Industrial Ethernet Development Platform
It enables the user to connect a Microcontroller based application to all market relevant Real-Time-Ethernet industrial networks with best-in-class real-time capabilities, like PROFINET, Ethernet/IP, EtherCAT, and others.
The extension board features a netX 52 system-on-chip. The netX SoC architecture is designed from the ground up for the highest demands on flexibility, determinism, and performance in terms of multi-protocol capability and low latency for short cycle times. The heterogeneous multi-core architecture features an ARM processor core, coupled with a flexible communication subsystem (xC) for varieties of industrial applications support.