Field Device Interface Command Caching for Protocol Bottlenecks
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Solution Overview
Problem
The low data rate of field level communication protocols creates a bottleneck at interface devices in industrial automation, preventing simultaneous execution of commands for multiple field devices connected through these devices.
Innovation Solution
Implementing a method where interface devices cache commands received for multiple field devices before executing them, allowing for simultaneous command execution by grouping commands based on field devices and utilizing a memory module to manage communication channels efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple field devices are connected to a single interface device using multiplexing schemes, then infrastructure costs are reduced and efficiency is improved, but a bottleneck is created at the interface device due to the low data rate of field level communication protocols
Solution Approach 1:
The interface device receives and caches multiple commands from the control device before executing them on the field devices. This preliminary buffering of commands allows the control device to send commands at a higher rate without being blocked by the slower field level communication protocol, thereby resolving the bottleneck while maintaining the multiplexing architecture
Solution Approach 2:
The interface device acts as an intermediary between the control device and field devices, using a memory buffer to decouple the high-speed control level communication from the low-speed field level communication. This intermediary buffering mechanism allows commands to be received and forwarded at different rates, eliminating the data rate bottleneck
2Reliability
If commands are executed sequentially on field devices due to protocol delays, then communication reliability is maintained, but the interface device cannot execute commands simultaneously on multiple field devices
Solution Approach 1:
Multiple commands are received and cached in advance before execution begins. This preliminary buffering enables the interface device to execute commands on multiple field devices in parallel or rapid succession, significantly improving throughput while maintaining reliability through proper protocol adherence during execution
Solution Approach 2:
The command execution process is segmented into distinct phases: command reception and buffering, and command execution on individual field devices. This segmentation allows the receiving function to operate independently and concurrently with the execution function, enabling simultaneous command reception and execution without interference
3Reliability
If the interface device waits for protocol completion before receiving the next command, then protocol synchronization is maintained, but overall command execution time increases
Solution Approach 1:
Commands are buffered in advance while the interface device is occupied with protocol synchronization and execution on previous commands. This preliminary buffering eliminates idle waiting time, as the interface device can immediately begin executing buffered commands once protocol synchronization is complete, thereby reducing overall execution time without compromising synchronization
Solution Approach 2:
The interface device maintains continuous useful action by receiving and buffering commands during the execution phase of previous commands. This continuous operation eliminates idle periods and ensures that the interface device is always engaged in productive work, either receiving commands or executing them, thereby minimizing total execution time
Data Source
AI summary
A method for communicating with at least one field device via an interface device, wherein each field device is connected to a channel of the interface device, where the method includes receiving a first command associated with a first field device, from an industrial device, communicating with the first field device over a first communication channel for executing the received first command, receiving at least one command associated with the at least one field device, from the industrial device, the at least one commands including at least one command associated with a second field device from the at least one field device, and caching the at least one command in a memory module prior to the execution of the first command.