SEL RTAC Tag Database — Architecture and Configuration
Key Takeaway
How the RTAC tag database works — tag types, naming conventions, quality attributes, system tags, scaling, aliasing, and organization for large substations.
Quick Answer
The RTAC tag database is the central data hub — all protocol drivers read data into tags and write from tags, all IEC 61131-3 programs access tags, and all HMI elements bind to tags. Tag types include BOOL, INT, DINT, REAL, STRING, TIME, and quality attributes.
Tag as Central Hub
Protocol client → Tags ← IEC 61131-3 Programs → Tags → Protocol server → SCADA Master. Tags → HMI displays. Everything connects through tags.
Tag Types
- BOOL — discrete status, relay word bits
- INT/DINT/UDINT — counters, integers
- REAL — analog measurements
- STRING — device identifiers
- TIME — durations, timestamps
Tag Quality
GOOD, BAD, UNCERTAIN. Propagated from protocol driver through to SCADA server and HMI. BAD quality means source device not communicating.
Naming Convention
Recommended: [Substation]_[Device]_[Function]_[Parameter]. Example: SUB1_SEL351_FDR1_IA_CURRENT.
System Tags
Built-in RTAC status: driver communication status, CPU load, memory, time sync quality.
Organization
Hierarchical folders — by device, by bay, by function. CSV import for large substations with hundreds of tags.
Frequently Asked Questions
Hierarchical folder structure — grouped by device, bay, or function. Each tag has a unique name, data type, scaling, and quality attributes.
GOOD means recently received from communicating source. BAD means communication lost. UNCERTAIN is transitional. Quality propagates to SCADA and HMI.