DTSU666 3‑Phase + mbpoll Command Reference

🔌 Standard Communication Settings (DTSU666) 

 Most DTSU666 meters use: 

 

 

 

 

 

 

 

 

 

 

 Protocol : Modbus RTU Baud Rate : 9600 Data Bits : 8 Parity : None Stop Bits : 2 Mode : Big‑endian Table : Input Registers (FC04) 

 

 

 

 

 

 

 

 

 

 

 

 

 

 Base communication block used in all commands: 

 

 

 

 

 

 

 

 

 

 

 -m rtu -b 9600 -P none -s 2 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 🧠 Critical Flags (Important) 

 

 

 

 

 

 Flag 

 Meaning 

 Required? 

 

 

 

 

 -t 3 

 Input Registers (Function 04) 

 ✅ Yes 

 

 

 :float 

 32‑bit floating point 

 ✅ Yes 

 

 

 -B 

 Big‑endian word order 

 ✅ Yes 

 

 

 -0 

 Zero‑based addressing 

 ✅ Yes 

 

 

 -a <id> 

 Slave address 

 ✅ Yes 

 

 

 -1 

 Poll once 

 Optional 

 

 

 -l 5000 

 Poll every 5 seconds 

 Optional 

 

 

 

 

 

 

 🔹 Phase‑to‑Neutral Voltages (L1‑N, L2‑N, L3‑N) 

 Register:  0x2006 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 3 :float -B -0 \ -r 0x2006 -c 3 \ /dev/ttyUSB0 -a 1 -1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 🔹 Line‑to‑Line Voltages (L1‑L2, L2‑L3, L3‑L1) 

 Register:  0x2000 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 3 :float -B -0 \ -r 0x2000 -c 3 \ /dev/ttyUSB0 -a 1 -1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 🔹 Phase Currents (L1, L2, L3) 

 Register:  0x200C 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 3 :float -B -0 \ -r 0x200C -c 3 \ /dev/ttyUSB0 -a 1 -1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 🔹 Total Active Power (kW) 

 Register:  0x2012 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 3 :float -B -0 \ -r 0x2012 -c 1 \ /dev/ttyUSB0 -a 1 -1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 🔹 Frequency (Hz) 

 Register:  0x2044 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 3 :float -B -0 \ -r 0x2044 -c 1 \ /dev/ttyUSB0 -a 1 -1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 🔹 Total Active Energy (kWh) 

 Register:  0x4000 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 3 :float -B -0 \ -r 0x4000 -c 1 \ /dev/ttyUSB0 -a 1 -1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 🔁 Continuous Polling Example (Every 5 Seconds) 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 3 :float -B -0 \ -r 0x2006 -c 1 \ -l 5000 \ /dev/ttyUSB0 -a 1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 🔢 Change Slave Address (Only One Meter Connected) 

 ⚠ Use Holding Registers (Function 03) for configuration. 

 Register:  0x002E 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 4 :int16 -0 \ -r 0x002E \ /dev/ttyUSB0 -a 1 -W -- 5 

 

 

 

 

 

 

 

 

 

 

 

 

 

 Changes slave ID from 1 → 5. 

 

 🧪 Quick Communication Test 

 Fastest health check: 

 

 

 

 

 

 

 

 

 

 

 mbpoll -m rtu -b 9600 -P none -s 2 \ -t 3 :float -B -0 \ -r 0x2006 -c 1 \ /dev/ttyUSB0 -a 1 -1 

 

 

 

 

 

 

 

 

 

 

 

 

 

 If you see ~230V → communication confirmed. 

 

 🚨 Troubleshooting Quick Guide 

 

 

 

 

 

 Symptom 

 Likely Cause 

 

 

 

 

 Timeout 

 Wrong address or wiring 

 

 

 4200+ volts 

 Reading wrong register 

 

 

 -8192 values 

 Wrong data type 

 

 

 Nonsense numbers 

 Missing  -B 

 

 

 No  /dev/ttyUSB0 

 USB‑RS485 not detected