Links and heartbeat
Every connection has its own role, its own two links and its own heartbeat. The panels below act on the connection selected in the rail (see Connections).
Role
Role decides how both links reach the Concentrator. Link A and Link B always share one role.
| Role | Behaviour |
|---|---|
| TCP Client (dial) | Dials the Concentrator's TCP-server receiver line (STCPIP=) at the address entered for each link |
| TCP Server (listen) | Listens for the Concentrator's TCP-client receiver line (TCPIP=) to dial in, and re-accepts automatically after the peer drops |
The role is locked while the connection is running. Go in the Receiver panel, or the start icon on the connection's row, starts it; Stop ends it. The status pill shows Idle or the live state.
Link A and Link B
Each link has its own host and port, defaulting to 127.0.0.1 with port 7001 for A and 7002 for B, a state pill, a Primary badge when it holds primacy, and a Make primary button.
- Link A always comes up with the connection and cannot be switched off on its own.
- Enable Link B brings the second link up and fans every send to both links, primary first. This is the split setting: a connection with Link B enabled sends on both.
- A primary drop promotes the surviving link automatically. There is no auto-revert; the promoted link stays primary until changed by hand.
- Make primary promotes a link explicitly. Disabling Link B while it holds primary hands the role back to A.
- A dial-role link that drops redials on a 5, 10, 20, then 30 second backoff. A listen-role link re-accepts instead. A link that has never connected is not promoted during its first few seconds, so a cold start does not hand primacy to a link that was never up.
[Image: the Links panel with both links up and A primary]
Heartbeat
Automatic heartbeat is on by default and sends the heartbeat signal every 30 seconds on every connected link, which keeps a Concentrator TCP-server line from tripping its TOUT2= idle timeout. The period is set in seconds beside the checkbox. HB signal takes the heartbeat bytes in the <NNN> escaped form; left empty, the receiver type's own idle or link-test signal is used.
Counters
- Delivered A and Delivered B — signals successfully written on each link.
- TX fails — one per failed-write transition, not one per retry.
- Promotions — how many times primacy changed hands.
- Campaign sent — signals sent by the running campaign.
Live log
The Log pane streams the selected connection's timestamped TX, RX and state lines as they happen, capped at the most recent 500 lines; Clear pane empties the display only. Every connection is written to the same log files on disk (see Getting started).