Heartbeat timeout to CSMS

How it presents

Symptom

Heartbeat timeout to CSMS — station may look Available locally while Cloud shows offline, sessions fail Authorize, or Heartbeat gaps appear in the CSMS timeline. protocol field note: keep evidence scrubbed and prove the ranked cause before module RMA on OCPP-F02.

Root causes (by observed frequency)

1. #1 DNS/TLS/path failure to the CSMS host

   Local Ready ≠ Cloud online

2. #2 Cellular RSSI/APN/SIM issue dropping the websocket
3. #3 NAT keepalive / firewall idle timeout killing OCPP
4. #4 Wrong OCPP URL or chargeBoxIdentity after board/SIM swap

Diagnostic procedure

1. 1. Confirm local UI Ready vs CSMS offline window timestamps

   Expected: Soft-offline pattern

   Tools: CSMS

2. 2. Resolve CSMS hostname and test TLS from the site segment

   Expected: DNS + TLS OK

   Tools: IT tools

3. 3. Check modem RSSI/APN/SIM if cellular backhaul

   Expected: RSSI usable; correct APN

   Tools: modem UI

4. 4. Verify OCPP URL and chargePointIdentity match commissioning

   Expected: Exact URL/ID

   Tools: HMI

5. 5. Adjust NAT keepalive/firewall with IT if path flaps on idle

   Tools: network admin

The fix

Heartbeat timeouts are backhaul/config until proven otherwise — not power electronics.

1. Prove the CSMS path (DNS, TLS, URL, identity) before board RMA.
2. Correct APN/SIM/antenna issues on cellular cabinets. Document readings and scrubbed photos for OCPP-F02 before closing the ticket.
3. Fix firewall/NAT idle timeouts that drop the websocket.
4. Restore Heartbeat interval and confirm stable Heartbeats for ≥15 minutes.
5. Only then escalate controller/modem hardware with a scrubbed evidence pack.