DDSU666 (Direct chint meter ) + mbpoll Command Reference

Version: 1.0
Prepared For: Field & Deployment Teams
Platform: Raspberry Pi / Linux
Tool: mbpoll

1. Purpose

This document explains how to communicate with the CHINT DDSU666 Direct Smart Meter using Modbus RTU and the mbpoll tool.

It covers:
• Reading electrical parameters
• Setting meter addresses
• Verifying communication
• Preparing for OpenEMS integration

2. Hardware & Software Requirements

Hardware
• DDSU666 (Direct Version)
• RS485 → USB Converter
• Raspberry Pi / Linux PC
• Correct RS485 wiring (A↔A, B↔B, GND recommended)

Software
Install mbpoll:

sudo apt update
sudo apt install mbpoll

Check serial port:

ls /dev/ttyUSB*

Example output:

/dev/ttyUSB0

 

3. Communication Parameters (Confirmed)

Parameter	Value
Protocol	Modbus RTU
Baud Rate	9600
Data Bits	8
Parity	None
Stop Bits	2
Format	8N2
Float Order	Big Endian
Addressing	0-Based

These parameters must always be used.

4. Standard mbpoll Format

All commands follow this format:

mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 -r <register> -c <count> /dev/ttyUSB0 -a <id> -1

Where:
•    <register> = Modbus register
•    <count> = Number of values
•    <id> = Meter address (NO.)

5. Electrical Parameters

Summary:

Voltage: 0x2000
Current: 0x2002
Active Power: 0x2004
Power Factor: 0x200A
Frequency: 0x200E
Energy: 0x4000

5.1 Voltage (V) — Register 0x2000

Meter ID = 1
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x2000 -c 1 /dev/ttyUSB0 -a 1 -1
Meter ID = 2
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x2000 -c 1 /dev/ttyUSB0 -a 2 -1

5.2 Current (A) — Register 0x2002

Meter ID = 1
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x2002 -c 1 /dev/ttyUSB0 -a 1 -1
Meter ID = 2
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x2002 -c 1 /dev/ttyUSB0 -a 2 -1

5.3 Active Power — Register 0x2004

Meter ID = 1
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x2004 -c 1 /dev/ttyUSB0 -a 1 -1

Meter ID = 2
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x2004 -c 1 /dev/ttyUSB0 -a 2 -1

5.4 Power Factor — Register 0x200A

Meter ID = 1
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x200A -c 1 /dev/ttyUSB0 -a 1 -1
Meter ID = 2
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x200A -c 1 /dev/ttyUSB0 -a 2 -1

5.5 Frequency (Hz) — Register 0x200E

Meter ID = 1
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x200E -c 1 /dev/ttyUSB0 -a 1 -1
Meter ID = 2
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x200E -c 1 /dev/ttyUSB0 -a 2 -1

5.6 Energy (kWh) — Register 0x4000

Meter ID = 1
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x4000 -c 1 /dev/ttyUSB0 -a 1 -1
Meter ID = 2
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x4000 -c 1 /dev/ttyUSB0 -a 2 -1

6. Reading Multiple Values

Use -c option to read multiple registers.

Example ( Voltage + Current Together)

mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x2000 -c 2 /dev/ttyUSB0 -a 1 -1

7. Meter Address

Register: 0x0006

mbpoll -m rtu -b 9600 -P none -s 2 -t 4:int16 -0 \
-r 0x0006 -c 1 /dev/ttyUSB0 -a 2 -1

Example Output:
[6]: 2

8. Changing Address

• Only one meter connected.
• Power cycle after change.

Change Address (2 → 1)
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:int16 -0 \
-r 0x0006 /dev/ttyUSB0 -a 2 -W -- 1
Power Cycle
Turn OFF → ON the meter.
Verify
mbpoll -m rtu -b 9600 -P none -s 2 -t 4:int16 -0 \
-r 0x0006 -c 1 /dev/ttyUSB0 -a 1 -1

9. Health Check

Voltage should be 220–240V.

mbpoll -m rtu -b 9600 -P none -s 2 -t 4:float -B -0 \
-r 0x2000 -c 1 /dev/ttyUSB0 -a 1 -1

10. Common Issues

Timeout Errors
•    Duplicate IDs
•    Wrong wiring
•    Wrong stop bits
•    Multiple meters during setup

Incorrect Float Values
Use -B option.

Current / Power = 0

Normal when:
•    No load
•    Bench testing

11. Deployment Workflow

For large installations:
•    Connect one meter
•    Convert to Modbus
•    Set address
•    Test voltage
•    Install
•    Repeat
•    Never deploy duplicate addresses.

Connect → Configure → Test → Install

12. System Status

✔ Modbus Enabled
✔ 9600 8N2 Confirmed
✔ Big-Endian Floats
✔ Multi-meter Bus Working
✔ Ready for OpenEMS