Integration of ZENNER's water meter

This document describes the complete integration solution for ZENNER water meters (DN25 / DN40) connected via KC21 data collector, using Modbus-RTU protocol and EB framework, and integrated into the ThinkLink platform.

The document includes:

• Device wiring and communication parameters
• ThinkLink platform usage instructions
• Telemetry data format and third-party subscription
• Advanced EB integration details (EBHelper, Thing Model, RPC)

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Part 1: User Guide

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2. Meter Device Information

2.1 Water Meter Specifications

• Brand: ZENNER
• Device Type: Water Meter
• Models: DN25 / DN40
• Power Supply: External power required
• Input Voltage: DC 12–24V

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2.2 Communication Parameters (RS485 / Modbus-RTU)

Parameter	Value
Protocol	Modbus-RTU
Baud Rate	9600 bps
Data Bits	8
Parity	Even
Stop Bits	1
Slave Address	Configurable

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2.3 Water Meter Wiring

Wire Color	Description
Red	Power +
Black	Power −
Yellow	RS485 A
Green / Blue	RS485 B

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2.4 Official Manuals

• https://active.clewm.net/E1Jg6l
• https://active.clewm.net/EeFfJo

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3. Data Collector Information (KC21)

3.1 Basic Information

• Model: KC21
• Power Supply: Battery powered
• External Power Output: 15V (for meter power supply)

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3.2 KC21 Wiring

Wire Color	Description
Red / Brown	Power +
Black	Power −
Blue	RS485 A
White	RS485 B

⚠️ Ensure RS485 A/B lines are connected correctly between the KC21 and the water meter.

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4. ThinkLink Platform Usage

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4.1 Add Device

1. Log in to the ThinkLink platform
2. Go to Device Management → Add Device
3. Search and add the following model:

ZENNER-BATTERY-21121

4. Complete device binding

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4.2 Parameter Configuration

Navigation path:

Device Management → Select Device → Configuration → RPC

Select RPC:

[EB SET] easy para

Parameters

Parameter	Description
period	Meter reading interval (seconds)
addr	Modbus slave address of the water meter start with 0x if hex type otherwise is DEC

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4.3 Third-Party Data Subscription

MQTT Topic

/v32/{Organization Account}/tkl/up/telemetry/{eui}

Sample Telemetry Payload

{
    "eui": "6353012af10a9331",
    "active_time": "2026-02-05T08:35:48.000Z",
    "thingModelId": "71719731542888453",
    "thingModelIdName": "zenner_21121",
    "telemetry_data": {
        "snr": 13.5,
        "rssi": -51,
        "battery": 3.37,
        "total_flow": 1,
        "update_time": 1770280548000
    }
}

Protocol Reference

• http://think-link.net/docs/zh/Protocol/ThinkLinkProtocol.html

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Part 2: Advanced Integration

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5. Data Acquisition via EBHelper

5.1 Communication Protocol

• Protocol: Modbus-RTU
• Implementation: EBHelper
• Business Type (BzType): 21121

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5.2 Modbus Register Mapping

Register Address	Description	Data Type
0x0007	EDC voltage status	Uint16BE
0x0008	EDC alarm status	Uint16BE
0x0004–0x0005	Total water consumption	FloatBE

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5.3 OTA Configuration

let otaConfig = getOtaConfig({
    BaudRate: 9600,
    StopBits: 1,
    DataBits: 8,
    Checkbit: CheckbitEnum.EVEN,
    Battery: true,
    ConfirmDuty: 60,
    BzType: 21121,
    BzVersion: 16
})

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5.4 EB Compilation Logic

• EBHelper is used to define Modbus polling logic
• Event configuration is defined in eventInfo
• OTA file is generated using buildOtaFile()
• Supports periodic Modbus polling and LoRa uplink

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6. Thing Model Mapping

6.1 Uplink Frame Structure

Port: 22

Uses the EBHelper standard frame format:

Field Name	Offset	Length (Bytes)	Description
version	0	1	Protocol version, fixed at 0x83
dataType	1	1	Fixed at 0x32
covStatus	2	1	Reserved byte (for internal COV processing)
status	3	1	Query event status
battery	4	1	Battery level
addr	5	1	Sub-device address
EDC Voltage	6	2	Big-endian format, Uint16BE
EDC Alarm	8	2	Big-endian format, Uint16BE
Total Flow	10	4	FloatBE, unit: m³

6.2 Thing Model Information

Item	Value
Thing Model Name	ZENNER
Thing Model ID Name	zenner_21121
Event Name	water

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6.2 Field Mapping

Field	Description
total_flow	Total water consumption
battery	Battery voltage
rssi	Signal strength
snr	Signal-to-noise ratio

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7. Payload Parsing Logic

7.1 Telemetry Parsing

• LoRa Port: 22
• Data Type: FloatBE
• Precision: 3 decimal places

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7.2 Parameter Parsing (RPC)

APP Address	Parameter
70	Polling interval (period)
150	Modbus slave address

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8. RPC Parameter Configuration

• RPC Name: [EB SET] easy para
• RPC ID Name: eb_set_easy_para

APP Address	Description
app_70	Polling period
app_150	Water meter Modbus address

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9. Summary

This solution provides a complete and reliable integration of ZENNER water meters into the ThinkLink platform using EB + KC21:

• Remote parameter configuration
• Periodic meter reading
• Standard MQTT telemetry for third-party systems
• Low power consumption and high stability

It is well suited for water management, irrigation automation, and smart utility projects.