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Connect Multispan AVH-14-M1 to Autoconnecto (Modbus over MQTT)
This guide is for customers and field engineers. It connects a Multispan AVH-14-M1 multifunction energy meter (RS-485 Modbus RTU) to Autoconnecto through a cellular DTU such as USR-DR154, using a dedicated Modbus gateway (keep any XY-MD02 / htgateway path separate).
Related:
- DR154 + XY-MD02 how-to:
dr154-modbus-mqtt.md - Engineer transport contract:
backend/docs/MODBUS_TUNNEL.md
What you are building
text
Autoconnecto --MQTT TX--> DR154 --RS485--> AVH-14-M1 (Modbus slave)
Autoconnecto <--MQTT RX-- DR154 <--RS485-- AVH-14-M1| Piece | Role |
|---|---|
| energygateway | MQTT token + MQTT_SERIAL |
| avh1 (child) | Slave ID, AVH-14-M1 register map, telemetry |
| DR154 | MQTT ↔ RS485 bridge |
| AVH-14-M1 | Modbus RTU float slave |
Official Modbus map (from AVH-14-M1 PDF)
Confirmed from the meter manual MODBUS (AVH 14-M1) pages:
| Item | Value |
|---|---|
| Slave address | 1–125 |
| Baud | 4800 / 9600 / 19200 / 38400 |
| Parity | None / Even / Odd |
| Datatype | Float — 32-bit little-endian byte swap (CDAB) |
| Read FC | 0x03 and 0x04 |
| Write FC | 0x06 / 0x10 (config/reset — not used for live telemetry) |
Each value occupies two holding registers. Autoconnecto uses HOLDING (FC3) + data type float32_cdab.
Energy (integer + fraction)
Per manual Note 1, energy is split across two floats (example 320126789.321 → int 320126789 + frac 0.321):
| Key | Addr | Meaning |
|---|---|---|
energy_kwh_int | 0 | kWh integer part |
energy_kwh_frac | 2 | kWh fractional part |
energy_kvah_int | 4 | kVAh integer |
energy_kvah_frac | 6 | kVAh fraction |
energy_kvarh_int | 8 | kVArh integer |
energy_kvarh_frac | 10 | kVArh fraction |
Total energy ≈ *_int + *_frac.
Voltages (phase values)
| Key | Addr | Meaning |
|---|---|---|
voltage_l1n | 12 | L1–N |
voltage_l2n | 16 | L2–N |
voltage_l3n | 20 | L3–N |
voltage_vln_avg | 24 | Avg V L-N |
voltage_l12 | 28 | L1–L2 |
voltage_l23 | 32 | L2–L3 |
voltage_l31 | 36 | L3–L1 |
voltage_vll_avg | 40 | Avg V L-L |
(Unit registers 14, 18, … exist on the meter: 0 = V, 1 = kV — not polled by default.)
Current, PF, frequency
| Key | Addr |
|---|---|
current_l1 / l2 / l3 / current_avg | 44 / 48 / 52 / 56 |
power_factor_l1 / l2 / l3 / power_factor_avg | 60 / 62 / 64 / 68 |
frequency_hz | 70 |
Power
| Key | Addr |
|---|---|
active_power_kw_l1 / l2 / l3 / total | 72 / 76 / 80 / 84 |
apparent_power_kva_l1 / l2 / l3 / total | 88 / 92 / 96 / 100 |
reactive_power_kvar_l1 / l2 / l3 / total | 104 / 108 / 112 / 116 |
Hours / RPM / max demand
| Key | Addr |
|---|---|
load_hours / load_minutes | 120 / 122 |
noload_hours / noload_minutes | 124 / 126 |
rpm | 128 |
md_kw / md_kva / md_kvar | 130 / 134 / 138 |
Autoconnecto setup
- Create Modbus gateway
energygateway(leavehtgatewayalone). - Copy gateway token → DR154 MQTT user / password / client ID.
- Connection mode MQTT serial; topics:
- Subscribe:
devices/<TOKEN>/modbus/tx - Publish:
devices/<TOKEN>/modbus/rx
- Subscribe:
- Add child
avh1, slave ID 1 (match meter). - Register map: addresses above, type HOLDING, data type float32 CDAB (Multispan), scale 1.
- UART on DR154 = meter baud (9600 8N1 recommended).
- Read now → check
voltage_l1n/voltage_l2n/voltage_l3n(or L-L if 3P-3W). - Then enable Auto poll.
DR154 checklist
text
AT+WKMOD=MQTT,NOR
AT+MQTTSVR=mqtt.autoconnecto.in,8883
AT+MQTTUSER=<ENERGY_GATEWAY_TOKEN>
AT+MQTTPSW=<ENERGY_GATEWAY_TOKEN>
AT+MQTTCID=<ENERGY_GATEWAY_TOKEN>
AT+MQTTSUBTP=1,1,devices/<TOKEN>/modbus/tx,0
AT+MQTTPUBTP=1,1,devices/<TOKEN>/modbus/rx,0,0
AT+SSLEN=ON
AT+UART=9600,8,1,NONE,NONE
AT+SWire A/B to meter Modbus terminals; remove PC from the bus.
Why earlier readings looked wrong
A different Multispan family map (AVH-14N 30000/40000 style) was applied first. That is not the AVH-14-M1 table. Combined with ABCD float decode instead of CDAB, voltages appeared as zeros or huge nonsense numbers.
Correct map + float32_cdab should show phase voltages near what the meter display shows.
Troubleshooting
| Symptom | Check |
|---|---|
| Timeout | Slave ID, baud match, A/B, MQTT token/topics |
| Voltage still nonsense | Confirm data type is float32_cdab, addresses 12/16/20 (L-N) or 28/32/36 (L-L) |
| L-N always 0 | Meter in 3P-3W — use L-L keys instead |
| Energy odd | Sum energy_kwh_int + energy_kwh_frac |
Checklist
- [ ] Separate energygateway token on DR154
- [ ] Meter + DR154 both 9600 (or both the same baud)
- [ ] Slave ID match
- [ ] Map from this AVH-14-M1 PDF (not 14N 30000 table)
- [ ] Data type float32_cdab
- [ ] Read now → phase voltages look right on avh1 telemetry