Field Device Safety Communication Without a Protocol Master
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Solution Overview
Problem
Existing automation systems require a master device for field devices to communicate, which is costly and limits their use in safety-relevant applications without a safety protocol master.
Innovation Solution
The automation system allows field devices to communicate directly with each other via a system bus, enabling them to simulate a master device and operate in parallel or slave modes without a central master, using a safety protocol based on the black-channel principle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety protocol master is used to ensure functional safety in automation systems, then safety compliance is achieved, but system cost increases significantly
Solution Approach 1:
Field devices are configured to monitor each other directly through the system bus without requiring a dedicated safety protocol master. Each field device can detect faults in other field devices and report them to the control device, enabling the system to self-monitor safety-critical functions while reducing dependency on expensive master devices
Solution Approach 2:
The system bus serves as an intermediary communication channel that enables direct monitoring between field devices. The control device acts as a mediator that receives fault reports from field devices and coordinates safety responses, replacing the need for a dedicated safety protocol master while maintaining safety compliance
2Ease of operation
If field devices communicate through a central control device (master), then communication control is simplified, but communication efficiency and data exchange speed between field devices decrease
Solution Approach 1:
The communication architecture is segmented into two layers: control plane (through control device) and data plane (direct field device-to-field device communication). This allows control commands to flow through the central control device while data exchange occurs directly between field devices, eliminating the bottleneck of master-mediated communication
Solution Approach 2:
The system adds a direct communication dimension between field devices alongside the existing hierarchical control dimension. Field devices can exchange data directly through the system bus while still receiving control commands from the control device, creating a multi-dimensional communication topology that improves efficiency without sacrificing control
Data Source
AI summary
An automation system includes a control device, a system bus, a first field device, and a second field device. The control device includes a system bus interface for communication with the field devices by the system bus, and each field device includes a data interface for communication by the system bus. Each field device includes a monitoring input for receiving a monitoring signal and a monitoring output for outputting a monitoring signal. The monitoring input of the first field device is coupled to the monitoring output of the second field device by the system bus, and the monitoring input of the second field device is coupled to the monitoring output of the first field device by the system bus.