System Redundancy

System Redundancy with PROFINET

Automation systems have always been designed to meet two key criteria: reliability and availability.  Reliability is the first priority- data that enters the network should pass through it unchanged and should always make it to its destination.  But availability is a more complex problem because it’s not just about moving bits across a network once they’re transmitted.  Instead, availability means […]

Redundancy Terms: S1, S2, R1, R2

System redundancy for PROFINET comes with some strange terminology: S1, S2, R1, and R2 all show up in technical and marketing literature.  They’re usually presented without much context, so we’ll clarify them here. System redundancy relies on the concept of multiple connections to a device or controller to maintain the system in the event of a failure.  In our article […]

PROFINET Media Redundancy + Media Redundancy

The redundant title of this article is your first clue to the topic of this article: PROFINET media redundancy. PROFINET media redundancy is optional with all conformance classes, but in some applications, it is critical for correct operation (for example, hot backup in a safety application).  PROFINET offers network media redundancy through a ring topology. PROFINET has two main media […]

PROFINET Controller Redundancy

The concept of redundancy in PROFINET is broken into several parts: device, network, media, and controller redundancy.  This article takes a look at controller redundancy and why it’s more complex than device redundancy. There are two moving parts that make Controller redundancy work: coordination between controllers (usually some vendor-specific communication between PLC applications) and how devices handle simultaneous connections (a […]

PROFINET Device Redundancy

It’s three A.M.  Third shift is in full swing when a distributed I/O rack decides to stop working.  But instead of stopping the line, the system seamlessly switches over to the redundant I/O rack and just logs a “maintenance requested” message with the operator.  The maintenance crew doesn’t have to scramble, and the night continues without a hitch.  That’s device […]