Reliable industrial communication depends on more than choosing the right protocol — it depends on bandwidth, latency, redundancy, and the safeguards built around data quality. This section covers the terms used to describe and measure that reliability.
| Term | Definition |
|---|---|
| Tag | A named reference to a specific data point, such as a sensor reading or setpoint, used to identify and access that value within a control or OPC system. |
| Latency | The delay between when data changes at its source and when that change is reflected to a client application. |
| Bandwidth | The maximum rate at which data can be transmitted across a given network connection. |
| Redundancy | The use of duplicate hardware, software, or communication paths to maintain system operation if a primary component fails. |
| Failover | The automatic switch to a backup system or component when a primary one fails, intended to maintain continuous operation. |
| QoS (Quality of Service) | A measure or guarantee of network performance characteristics, such as reliability, latency, and bandwidth, often configurable in OPC UA PubSub. |
| Data Archiving | The process of moving historical process data into long-term storage for compliance, analysis, or capacity reasons. |
| CRC (Cyclical Redundancy Check) | An error-detection method that verifies data wasn’t corrupted during transmission by comparing checksums. |