Viewing Real-Time Values
This describes how to check the current values of registered PLCs / tags in real time. The gateway provides three live views.
| View | Polling interval | Purpose |
|---|---|---|
/ui/connect/list (OPC on the left + tag table on the right) | 5 s | See all tag values of one OPC at a glance |
/ui/connect/tag-view/{opc_id}/{tag_id} (single-tag live chart) | 1 s | Trend and time series of a specific tag |
/ui/main card | 1 s | Gateway system status (CPU/memory/network/Sparkplug, etc.) |
1. Viewing from the [Connection List] screen (/ui/connect/list)
This is the simplest method.
- Click the Connected List icon in the left sidebar, or the main card Connected List (N)
- Click the PLC row you want to view in the [OPC List] on the left
- The tag list and current values for that PLC appear on the right.
- The view refreshes automatically every 5 seconds.
For details on columns / actions, see Connection List / Tag List Screen.
2. Single-tag live chart (/ui/connect/tag-view/{opc_id}/{tag_id})
To examine a specific tag's time series in depth, click the tag row → you are taken to a separate tag-view page (or enter the URL directly).
2.1 Screen layout
┌────────────────────────────────────────────────────────────┐
│ ⊙ {OPC_ID} / {TAG_ID} [←] [↻] │
├────────────────────────────────────────────────────────────┤
│ [태그 메타 패널] │
│ tag_id / java_type / plc_address / opc_id / 마지막 갱신 │
├────────────────────────────────────────────────────────────┤
│ [값 추이 차트] [범위 콤보 ▼] │
│ ┌──────────────────────────────────────────────────────┐ │
│ │ (수치/불리언 — ECharts 라인 / STRING — vis 박스) │ │
│ │ │ │
│ │ [── dataZoom 슬라이더 (연한 그레이) ────────] │ │
│ └──────────────────────────────────────────────────────┘ │
└────────────────────────────────────────────────────────────┘
2.2 Chart types (selected automatically)
| Data type | Chart |
|---|---|
Integer / Long / Float / Double | ECharts line — smooth spline + right-hand Y axis |
Boolean | ECharts step end — 0/1 staircase |
String | vis-timeline box — groups consecutive runs of the same value into a single box (state machine visualization) |
2.3 Chart interactions
| Feature | Description |
|---|---|
| Range combo box | 1분 / 5분 / 10분 / 30분 / 1시간(default) / 3시간 / 12시간 / 24시간 — on selection, data is immediately re-fetched from Cassandra tm_tag_point |
| dataZoom slider | Horizontal bar at the bottom of the chart — drag with the mouse to zoom / pan horizontally. Light gray tone (changed from the previous darker color) — does not obscure the chart body |
| Automatic append | The 1-second polling pushes new values into the chart (incremental append, no full redraw) |
| Mouse hover | Tooltip showing the timestamp in ms plus the value |
| STRING chart refresh | History is sorted ASC and the entire vis dataset is rebuilt — no flicker for consecutive runs of the same value |
Uses the same tone / same data as the right-hand chart in the OPC-UA Node Viewer — except that tag-view shows a single tag full screen, while the opcua viewer shows a tree plus a small chart panel.
3. Table columns (reference)
[OPC List] on the left
| Column | Meaning |
|---|---|
| PLC | Protocol | Per-protocol logo + type |
| Connection status | 🟢 connected / 🔴 disconnected / ⬜ unknown |
| OPC ID / name / description | Identifier / user label |
| Collection interval (ms) | timecycle |
| Auto start / asynchronous | Option ✓ / - |
| Connected tag count | Number of tags on that OPC |
| Collection count | Cumulative reads since boot (point_count) |
| Collection status | 🟢 normal / 🟧 abnormal / ⬜ stopped |
| Actions | ▶ start / ⏹ stop / 🔧 edit / 🗑 delete |
(For the full original 14 columns, see Connection List)
[Tag List] on the right
| Column | Meaning |
|---|---|
| TAG ID / name | Identifier / user label |
| PLC address | Where the value is read from (e.g. D0, M10, 40001) |
| Data type | INT / DOUBLE / BOOL / STRING ... |
| Last value | Most recent collection (rounded solid badge — pp-cell-pill tone. Column width 160px) |
| Update time | Timestamp of the last refresh |
| Read status | OK (solid green) / ERROR (solid red) |
| Read error message | Reason for failure (empty on success) |
| Actions | ✏ inline write / 📈 chart (go to tag-view) |
At-a-glance view on the main screen
Returning to [Home] at the top (or clicking the logo in the upper left) shows the overall gateway status on a single screen.
| Display area | What it shows |
|---|---|
| CPU / memory / disk gauges | Resource status of the gateway PC |
| Connection / tag counts | Summary of total registered counts |
| PLC connection and collection status | Number of healthy / failed connections, cumulative collection count |
| Throughput (mps) | Trend graph of messages processed per second |
A gauge turning red means resources are running short. Contact your system administrator.
For Motor Sense
MOTOR_SENSE type connections are displayed as per-asset cards instead of the standard tag table.
- HEALTH INDEX card — asset health index (imbalance / alignment / bearing, etc.)
- SIGNAL card — signal values such as vibration / temperature / voltage
These refresh automatically at 1-second intervals; no separate refresh indicator is shown.
Retrieving values from external systems
If another system (dashboard, analytics tool, etc.) needs to receive values from the gateway, you can choose one of the following methods.
| Method | Who uses it |
|---|---|
| MQTT subscription | General IIoT systems |
| Sparkplug B subscription | Ignition / HiveMQ Edge / standard SCADA |
| REST API query | Custom-built dashboards / backends |
| Exposure as an OPC-UA server | External SCADA connecting as an OPC-UA client |
Detailed configuration / topic / endpoint specifications are in Advanced — REST API / Advanced — Sparkplug B.
Frequently asked questions
Q. Values are coming in, but they update far too slowly
Most likely the collection interval was set too long when the tag was registered. Try reducing 수집 주기 (ms) in PLC registration [Edit]. 1000 ms (= 1 second) is usually a good choice.
Q. A 5-second screen refresh is too slow for me
The table in /ui/connect/list refreshes every 5 seconds. To view a single tag faster, click that tag to go to the single-tag live chart (/ui/connect/tag-view) — it uses 1-second polling. To view many tags quickly at the same time, use a separate dashboard tool (Grafana, etc.) alongside. See Application Management.
Q. Some tags on the same PLC are fine while others show errors
If only certain tags fail, it is usually because the PLC address notation for those tags is wrong or the format qualifier (format) does not match. Re-check just that one row via [Edit].