Shared-Setpoint SDO Control With Redundant Master Election
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Solution Overview
Problem
Current data center systems are limited in the number of devices that can be networked together due to communication constraints, and manual intervention is required to designate a new master device in case of failure, which affects efficiency and reliability.
Innovation Solution
The use of the Service Data Objects (SDO) protocol to expand the number of devices in a group and implement redundant master control through master election techniques, optimizing busload and communication efficiency by prioritizing frame transmissions and employing frame triggering and suppression mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional Ethernet-based approaches are used for device communication, then each controller requires a separate Ethernet connection, but the group size is limited by Ethernet switching capacity
Solution Approach 1:
Multiple device controllers share a common communication bus (CAN bus) instead of requiring separate Ethernet connections. The SDO protocol enables multiple slaves to communicate with the master over a single bus infrastructure, consolidating what would otherwise require multiple independent network connections and switches.
Solution Approach 2:
The communication bus serves multiple functions simultaneously: it carries control commands from master to slaves, status information from slaves to master, and coordination signals for master election. This multi-functional use of a single bus infrastructure eliminates the need for dedicated communication channels for each device.
2Reliability
If a single master device controls the group, then control is centralized, but manual intervention is required when the master fails
Solution Approach 1:
Slave devices are pre-configured with their capability to become master and have the necessary control logic prepared in advance. When master failure occurs, the election process immediately activates among slaves based on predetermined criteria (device ID, capability flags), eliminating the need for manual configuration or intervention.
Solution Approach 2:
The system performs automatic master election and failover without requiring human intervention. Slaves autonomously detect master failure, execute the election algorithm to select a new master, and resume normal group operation, making the system self-healing and eliminating manual master replacement tasks.
3Loss of information
If all device controllers transmit SDO messages simultaneously, then communication is comprehensive, but busload increases and efficiency decreases
Solution Approach 1:
SDO messages are segmented into different priority levels and transmission categories. Critical control commands and status updates are separated from routine data exchanges, allowing high-priority messages to be transmitted immediately while lower-priority traffic is scheduled during available bus capacity, preventing complete bus saturation.
Solution Approach 2:
Instead of continuous simultaneous transmission, SDO messages are transmitted in periodic cycles with structured timing. The master controls the transmission rhythm, initiating SDO exchanges at scheduled intervals and suppressing redundant transmissions, which reduces overall busload while ensuring all necessary information is communicated within each cycle.
Data Source
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AI summary
Techniques for group control using service data objects (SDO) are disclosed. A device controller is configured to perform operations including: receiving, from device controllers that are configured to control devices so that the devices operate based on a shared set point, SDO messages using an SDO protocol; determining that the device controller is a master device controller for the device controllers, based at least on the SDO messages; and sending a setpoint update message including a modified value of the shared set point, using the SDO protocol, to slave device controllers in the device controllers, wherein a slave device controller in the slave device controllers is configured to adjust operation of at least one slave device in the devices, based at least on the setpoint update message.