Pressure Controller Eavesdropping for Latency Reduction
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Solution Overview
Problem
Existing communication systems in closed-loop control systems, such as semiconductor manufacturing tools, suffer from inefficiencies due to indirect data transfer and high latency, as pressure controllers receive measurements indirectly from tool controllers rather than directly from sensors, leading to increased message traffic and non-determinism.
Innovation Solution
An improved pressure controller with a local message processor and control processor that can 'eavesdrop' on messages not intended for it, allowing direct receipt of pressure measurements from sensors without requesting them from the tool controller, thereby reducing the burden on the tool controller and minimizing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure controller requests pressure measurements from the tool controller, then the pressure controller can obtain pressure data, but the communication latency increases and message traffic increases
Solution Approach 1:
The pressure controller extracts and processes pressure measurement data directly from the digital bus messages, removing the intermediate step of requesting data from the tool controller. This allows the pressure controller to obtain measurements directly from sensor messages without the additional communication overhead through the tool controller.
Solution Approach 2:
The digital bus acts as an intermediary communication medium that allows the pressure controller to access sensor data without direct sensor-to-controller communication. The bus carries sensor messages that the pressure controller can intercept and process, eliminating the need for separate request-response cycles through the tool controller.
2Loss of information
If the pressure controller polls the tool controller for measurements, then the pressure controller receives data, but the message traffic on the digital bus increases
Solution Approach 1:
The pressure controller merges its data acquisition function with the existing digital bus communication infrastructure. Instead of generating separate poll requests, the controller utilizes the same bus messages that carry sensor data to other devices, combining multiple data acquisition needs into a single communication stream.
Solution Approach 2:
The digital bus serves multiple functions simultaneously: it carries sensor data to the tool controller, provides data to the pressure controller, and enables other communication functions. This multi-functionality eliminates the need for dedicated poll requests from the pressure controller, reducing overall message traffic.
Data Source
AI summary
A tool includes a chamber, a network, a sensor, a tool controller, and a pressure controller. The network carries messages to and from devices on the network. A header portion of a message indicates a sender of the message and at least one intended recipient of the message. The sensor measures a pressure within the chamber. The sensor, tool controller, and pressure controller are on the network. The pressure controller controls the pressure within the chamber in response to measurements provided by the sensor and in response to a set point provided by the tool controller. The pressure controller processes header portions of all messages carried on the network to determine the intended recipients of each message and processes at least part of data portions of both messages intended for the pressure controller and at least some messages not intended for the pressure controller.