Troubleshooting
No Display / Meter Not Powering On
| Symptom |
Possible Cause |
Solution |
| Blank LCD |
No auxiliary power |
Check terminals 5-6: verify 85-277V AC present |
| Blank LCD |
Blown fuse/breaker |
Check circuit protection upstream |
| Dim display |
Low voltage |
Measure voltage at terminals 5-6 (min 85V AC) |
| Display flickering |
Loose connection |
Tighten terminal screws on 5-6 |
No Modbus Communication
| Symptom |
Possible Cause |
Solution |
| No response from meter |
Wrong baud rate |
Verify baud rate matches (default: 9600) |
| No response from meter |
Wrong address |
Verify Modbus address (default: 1) |
| No response from meter |
Wrong parity |
Set to EVEN (default) |
| Garbled data |
RS485 wiring swapped |
Swap D+ and D- wires |
| Intermittent communication |
Poor grounding |
Connect RS485 shield (terminal 11) |
| Bus errors |
No termination |
Add 120Ω resistor at bus ends for long runs |
Modbus Debugging via Tasmota Console
This enables verbose serial logging to see Modbus traffic in the Tasmota console.
Incorrect Readings
| Symptom |
Possible Cause |
Solution |
| Zero current reading |
CT not connected |
Check Rogowski coil cables on terminals 15-20 |
| Zero current reading |
CT ratio = 1 |
Set CT ratio to match coil rated current |
| Negative power reading |
CT reversed |
Check coil arrow direction (source → load) |
| High power reading |
CT on wrong conductor |
Verify CT1→L1, CT2→L2, CT3→L3 |
| Wrong voltage reading |
Wrong system type |
Verify 3P4W/3P3W/1P2W setting |
| Inaccurate readings |
CT ratio mismatch |
Match CT ratio to installed coil model |
Wi-Fi Connection Issues
| Symptom |
Possible Cause |
Solution |
| Cannot connect to Wi-Fi |
Wrong credentials |
Reset to AP mode (see below) |
| Intermittent disconnection |
Weak signal |
Check RSSI in console: Status 5 |
| Device not on network |
DHCP issue |
Set static IP: IPAddress1 192.168.1.x |
| Slow telemetry |
Wi-Fi power save |
Increase Sleep setting: Sleep 0 (no sleep) |
Reset to AP Mode
Method 1 — Via console:
Method 2 — Hardware reset:
- Press and hold the reset button on ESP32-C3 for 10+ seconds
- Device restarts in AP mode with SSID "RS-EMON3P"
MQTT Connection Errors
| Symptom |
Possible Cause |
Solution |
| MQTT not connecting |
Wrong host/port |
Verify broker address and port (1883/8883) |
| TLS handshake failure |
Fingerprint mismatch |
Update MqttFingerprint1 with current cert |
| TLS handshake failure |
Wrong port |
TLS requires port 8883, not 1883 |
| Authentication failed |
Wrong credentials |
Verify MQTT username/password |
| Connection drops |
Broker unreachable |
Check network path to broker |
Check MQTT Status
Shows current MQTT connection state, broker, and topic.
Home Assistant Not Discovering Device
| Symptom |
Possible Cause |
Solution |
| No entities in HA |
Wrong discovery prefix |
Verify SetOption19 0 and Prefix homeassistant |
| No entities in HA |
MQTT not connected |
Check MQTT connection first |
| Stale entities |
Old discovery messages |
Restart Tasmota: Restart 1 |
| Duplicate entities |
Multiple devices same topic |
Verify unique topic per device |
OTA Update Failures
| Symptom |
Possible Cause |
Solution |
| Update fails to start |
Wrong OTA URL |
Verify URL is accessible and HTTPS |
| Update fails mid-way |
Unstable Wi-Fi |
Ensure stable connection before updating |
| Device unresponsive after update |
Corrupted firmware |
Flash via serial (recovery mode) |
Rogowski Coil Positioning Issues
| Symptom |
Possible Cause |
Solution |
| Intermittent zero readings |
Coil not fully closed |
Verify latch is clicked shut with no gap |
| Erratic readings |
Coil near high-EMI source |
Move coil away from VFDs, contactors |
| Phase error |
Incorrect orientation |
Arrow must point toward load |
| Low accuracy |
Conductor not centered |
Position conductor in center of coil opening |
RS485 Bus Termination
When to Install 120Ω Termination
- Required: Bus length > 10 meters
- Required: Baud rate > 9600
- Install: At each physical end of the bus (only 2 resistors total)
- Remove: If present on every node (causes signal attenuation)
Verification
Measure resistance across D+ and D- at one end of the bus (power off):
- With termination: ~60Ω (two 120Ω resistors in parallel)
- Without termination: >10kΩ (high impedance)
Getting Support
If you cannot resolve an issue, see Support & Contact for support channels.