Connections & Tags¶
A connection is one data source — a PLC, an internal memory area, an MQTT broker, or an external web API. A tag is one data point read from (or written to) a connection — a single PLC register, an internal variable, an MQTT topic, and so on. Widgets on a view are bound to tags, not directly to connections.
Open Setup → Connections to manage both.
The connections diagram¶
Every gateway ships with one built-in connection, SCADash Server — an internal data source for memory tags that don't come from an external device (useful for calculated values, flags, or testing a view before real PLC data is available). Add more connections with the + button.
Switch to the list icon (top right) for a table view instead of the diagram:
Adding a connection¶
Click +, then fill in:
| Field | Notes |
|---|---|
| Name | How this connection appears throughout SCADash |
| Type | WebAPI, MQTTclient, or internal out of the box — install a plugin for PLC protocol drivers (Modbus, Siemens S7, Mitsubishi, EtherNet/IP, and others) |
| Polling | How often to read from this connection |
| Enable | Whether this connection is active |
Once a connection is added, its Type determines what further protocol-specific fields appear (address, port, slave ID, etc. — these vary per driver).
Click the pencil icon on an existing connection's card to edit its name and polling interval:
Managing tags¶
Click the link (chain) icon on a connection's card to open its tag list:
Click + to add a tag:
| Field | Notes |
|---|---|
| Device | Which connection this tag belongs to |
| Tagname | The tag's name, used when binding a widget to it |
| Type | number, boolean, or string |
| Init value | The tag's value before the connection has reported anything |
| Description | Free text |
For a PLC connection (added via a plugin), the tag dialog also asks for the PLC-side address to read from or write to — the exact address format depends on the driver (for example, a Modbus register number vs. a Siemens S7 DB address).