1. Sensor Overview

Model catalog

Search for these models in ThinkLink by name or ID.

Model type	Name	id_name	Platform model ID
RPC	[CT30xLF-A0 ACT] 21308	ct30xlfa0_action_21308	841830626125414403
RPC	[CT30xLF-A0 GET] 21308	ct30xlfa0_get_21308	841830626125414402
RPC	[CT30xLF-A0 SET] 21308	ct30xlfa0_set_21308	841830626125414401
Template	CT30xLF-A0	ct30xlfa0_21308	841830626125414404
Thing Model	[CT30xLF-A0]	ct30xlfa0_21308	841827660052037632
Thing Model	[REJEEE-21308-CT30xLF-A0资产] 区域聚合	ct30xlfa0_asset_21308	119677174411063300
Parameter Thing Model	[CT30xLF-A0-PARA]	ct30xlfa0_para_21308	841830626125414400

The CT30x-LF-A0 is a LoRa smart switch panel manufactured by Nanjing REJEEE Electronic Technology Co., Ltd. It uses a standard 86-type wall switch enclosure and can replace traditional mechanical switches without rewiring — simply connect in series with the fire wire for remote wireless control. The device supports 1–3 channel control (CT301 single, CT302 dual, CT303 triple), making it ideal for warehouses, server rooms, and office buildings.

In this integration solution, the device model is CT30x-LF-A0, the business code is 21308, and the template name is CT30xLF-A0.

2. Product Features

LoRa/LoRaWAN communication with local + remote control
Standard 86-type panel — direct drop-in replacement for mechanical switches
Fire wire (optionally neutral wire) power, max 400W per channel
Single, dual, and triple control variants
Built-in antenna, easy installation
Class C always-on — zero downlink latency

3. Application Scope

Warehouse lighting remote control
Server room equipment power management
Office building centralized lighting control
Factory floor lighting retrofit

4. Specifications

Parameter	Value
Communication	LoRa / LoRaWAN
Frequency	470–510 MHz (CN470)
TX Power	Max 22 dBm
RX Sensitivity	-141 dBm (SF12, BW125kHz)
Power Supply	Fire wire AC85V–265V
Max Load	400W per channel
Standby Power	≤0.22W
Dimensions	86mm × 86mm × 34mm
Operating Environment	-30℃ ~ +70℃, ≤95% RH

5. Data Acquisition

5.1 Protocol Overview

The CT30x-LF-A0 uses a custom TLV variable-length frame protocol over LoRaWAN FRMPayload. Data types are identified by a Type byte — no port-based dispatch is used.

5.2 TLV Frame Structure

Type Range	Format	Description
0x00–0x0F, 0xFF	T+V (fixed length)	Basic sensor types, no Length byte
0x10+	T+L+V (variable length)	Includes Length byte for extensibility

5.3 Uplink Data Types

Type	Name	Length	Description
0x00	Device Info	2 bytes	version(3b) + battery_level(5b) + reserve(1B)
0x09	Switch Status	1 byte	Bitmask per channel
0x1A	Current / Voltage	2–4 bytes	current(int16BE, mA) [+ voltage(int16BE, 0.1V)]
0x1B	Power	≥4 bytes	active power(uint32BE, W)

5.4 Uplink Example

FRMPayload (hex): 003300 0901 1A04011D08D1 1B040000003F

Parsed:

Device Info: version=1, battery_level=19
Switch: channel 1=ON
Current=285mA, Voltage=225.7V
Power=63W

6. Thing Model

6.1 Basic Information

Telemetry Thing Model

Name: [CT30xLF-A0]
id Name: ct30xlfa0_21308

Parameter Thing Model

Name: [CT30xLF-A0-PARA]
id Name: ct30xlfa0_para_21308

6.2 Telemetry Parser Script

javascript

let payload = msg?.userdata?.payload;
if (!payload) return null;
let bytes = Buffer.from(payload, 'base64');
let data = {};
let i = 0;
while (i < bytes.length) {
    let type = bytes[i++];
    if ((type >= 0x00 && type <= 0x0F) || type === 0xFF) {
        switch (type) {
            case 0x00:
                let info = bytes[i++];
                data.version = (info >> 5) & 0x07;
                data.battery_level = info & 0x1F;
                data.reserve = bytes[i++];
                break;
            case 0x09:
                let sw = bytes[i++];
                data.switch_1 = (sw & 0x01) === 0x01;
                data.switch_2 = (sw & 0x02) === 0x02;
                data.switch_3 = (sw & 0x04) === 0x04;
                data.switch_status = sw;
                break;
            default: i = bytes.length; break;
        }
    } else {
        let len = bytes[i++];
        let value = bytes.slice(i, i + len);
        i += len;
        switch (type) {
            case 0x1A:
                if (len >= 2) data.current = value.readInt16BE(0);
                if (len >= 4) data.voltage = value.readInt16BE(2) / 10.0;
                break;
            case 0x1B:
                if (len >= 4) data.power = value.readUInt32BE(0);
                break;
        }
    }
}
return {
    telemetry_data: data,
    server_attrs: null,
    shared_attrs: null
};

7. Third-Party Platform Data Subscription

7.1 MQTT Topic

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

7.2 Example Reported Data

json

{
    "eui": "0123456789abcdef",
    "active_time": "2026-05-11T09:00:00.000Z",
    "thingModelId": "21308",
    "thingModelIdName": "ct30xlfa0_21308",
    "telemetry_data": {
        "snr": 10.5,
        "rssi": -45,
        "switch_1": true,
        "switch_2": false,
        "switch_3": true,
        "switch_status": 5,
        "current": 285,
        "voltage": 225.7,
        "power": 63,
        "version": 1,
        "battery_level": 19
    }
}

8. RPC

8.1 Parameter Configuration RPC (SET)

Report Period Configuration

Name: [CT30xLF-A0 SET] 21308
id Name: ct30xlfa0_set_21308

Parameters

Parameter	Type	Description
period_up	number	Upload period in seconds, range 1-65535

RPC Script

javascript

const rpcName = "ct30xlfa0_set_21308";
let classMode = (device && device.shared_attrs && device.shared_attrs.class_mode) || "ClassC";

let dnBuffer = Buffer.alloc(4);
dnBuffer[0] = 0x02;
dnBuffer[1] = 0x11;
dnBuffer.writeUInt16BE(params.period_up, 2);

let paraDef = {
    app_11: {name: "period_up", field_name: "period_up", unit: "s", type: "uint16BE"}
};

let readBuffer = Buffer.alloc(2);
readBuffer[0] = 0x01;
readBuffer[1] = 0x81;

let paraDownBuffer = Buffer.alloc(dnBuffer.length + readBuffer.length);
dnBuffer.copy(paraDownBuffer, 0);
readBuffer.copy(paraDownBuffer, dnBuffer.length);

let msgQue = Utils.makeParaSetMSG({
    device: device,
    classMode: classMode,
    rpcName: rpcName,
    params: params,
    paraDownBuffer: paraDownBuffer,
});
if (msgQue.length === 0) return null;
return msgQue;

Downlink payload: 0x02 0x11 + period_up(uint16BE), sent via LoRaWAN transparent downlink (port 51).

8.2 Parameter Read RPC (GET)

User Configuration Read

Name: [CT30xLF-A0 GET] 21308
id Name: ct30xlfa0_get_21308

No parameters. After reading, the device returns configuration data including period_up and period_read.

RPC Script

javascript

let dnBuffer = Buffer.alloc(2);
dnBuffer[0] = 0x01;
dnBuffer[1] = 0x81;

let msg = RPCHelper.makeMSG({
    msgType: Utils.msgType.transParent,
    device: device,
    dnBuffer: dnBuffer,
    sleepTime: 2000
});
return [msg];

Downlink payload: 0x01 0x81, sent via LoRaWAN transparent downlink (port 51).

8.3 Switch Control RPC (ACTION)

Multi-Channel Switch Control

Name: [CT30xLF-A0 ACT] 21308
id Name: ct30xlfa0_action_21308

Parameters

Parameter	Type	Description
switch_1	boolean	Channel 1 on/off
switch_2	boolean	Channel 2 on/off
switch_3	boolean	Channel 3 on/off

RPC Script

javascript

let mask = 0x00;
let action = 0x00;
if (params.switch_1 !== undefined) { mask |= 0x01; if (params.switch_1) action |= 0x01; }
if (params.switch_2 !== undefined) { mask |= 0x02; if (params.switch_2) action |= 0x02; }
if (params.switch_3 !== undefined) { mask |= 0x04; if (params.switch_3) action |= 0x04; }
if (mask === 0x00) return null;

let dnBuffer = Buffer.alloc(3);
dnBuffer[0] = 0x23;
dnBuffer[1] = mask;
dnBuffer[2] = action;

let msg = RPCHelper.makeMSG({
    msgType: Utils.msgType.transParent,
    device: device,
    dnBuffer: dnBuffer,
    sleepTime: 2000
});
return [msg];

Downlink payload: 0x23 + mask(1B) + action(1B), sent via LoRaWAN transparent downlink (port 51).

9. Template Selection

In the ThinkLink platform, search for the template:

CT30xLF-A0

Or search by business type:

21308 / LoRa Smart Switch / REJEEE Light Control Panel

Supplementary Notes

Default device parameters can be configured via the SensorTool desktop utility (requires disassembly and power-off).
CT301/CT302/CT303 share the same thing model; the channel count is determined by the hardware variant.
The device is Class C (always-on) — downlink commands execute immediately with no delay.
The neutral wire is optional — connecting it can resolve LED flicker issues in single-fire-wire installations.
Do not wire the device while powered on.

LoRaWAN Gateway

Product Manuals

Current Configuration

Current Platform Access

Legacy WebServer

LoRaWAN EB Collector

LoRaWAN Sensor

Agriculture

BMS

Customize

Industry

ManThink

Meter

1. Sensor Overview ​

Model catalog ​

2. Product Features ​

3. Application Scope ​

4. Specifications ​

5. Data Acquisition ​

5.1 Protocol Overview ​

5.2 TLV Frame Structure ​

5.3 Uplink Data Types ​

5.4 Uplink Example ​

6. Thing Model ​

6.1 Basic Information ​

6.2 Telemetry Parser Script ​

7. Third-Party Platform Data Subscription ​

7.1 MQTT Topic ​

7.2 Example Reported Data ​

8. RPC ​

8.1 Parameter Configuration RPC (SET) ​

Parameters ​

RPC Script ​

8.2 Parameter Read RPC (GET) ​

RPC Script ​

8.3 Switch Control RPC (ACTION) ​

Parameters ​

RPC Script ​

9. Template Selection ​

Supplementary Notes ​

1. Sensor Overview

Model catalog

2. Product Features

3. Application Scope

4. Specifications

5. Data Acquisition

5.1 Protocol Overview

5.2 TLV Frame Structure

5.3 Uplink Data Types

5.4 Uplink Example

6. Thing Model

6.1 Basic Information

6.2 Telemetry Parser Script

7. Third-Party Platform Data Subscription

7.1 MQTT Topic

7.2 Example Reported Data

8. RPC

8.1 Parameter Configuration RPC (SET)

Parameters

RPC Script

8.2 Parameter Read RPC (GET)

RPC Script

8.3 Switch Control RPC (ACTION)

Parameters

RPC Script

9. Template Selection

Supplementary Notes