If you use the C programming language to develop products, you can use Link SDK for C provided by IoT Platform to simplify the development process. The SDK allows you to connect devices to IoT Platform with ease. This article describes the usage notes, features, and versions of Link SDK for C.

Usage notes

  • You can use Link SDK for C to connect devices with IoT Platform over the Internet.
  • You can configure Link SDK for C to implement multiple features to manage and monitor your devices. For more information, see Features.
  • You can customize Link SDK for C based on your business needs. For more information, see Obtain the SDK.
  • You can port Link SDK for C based on operating systems or hardware platforms. For more information, see Port the SDK.
    Link SDK for C may not support devices that use a microcontroller unit (MCU) and a module for communication. In this case, you can develop the SDK based on the protocol. For more information, see the following articles:


Type Feature Description Reference
Device connection Connection over MQTT

Establishes an MQTT connection between a device and IoT Platform to achieve communication.

Notice If you need to push messages from IoT Platform to devices, use the MQTT protocol for connection.

Connection over MQTT

Connection over HTTPS

Establishes an HTTPS connection between a device and IoT Platform. Then, the device can submit data to IoT Platform.

Connection over HTTPS

Device authentication
  • Supports presetting secrets for device authentication and supports dynamic registration by using HTTPS or MQTT.
  • Supports using X.509 certificates for device authentication.

Connection over MQTT

Connection over HTTPS

Connection by using X.509 certificates

Message communication RRPC Sends messages from IoT Platform to devices by using remote synchronous calls.


Broadcast communication Broadcasts messages from the IoT Platform server to devices. The devices do not need to subscribe to broadcast topics.

Broadcast communication

Device management Thing Specification Language (TSL) models Manages devices based on TSL models. You do not need to convert data formats during interaction between devices and IoT Platform. This way, development costs are reduced.

TSL models

Device tags Manages devices by using custom device tags.

Device tags

Device jobs Initiates jobs on multiple devices at the same time. The jobs are categorized into the following types: jobs to set properties, jobs to asynchronously call services, and custom jobs.

Device jobs

Device shadows Caches device status. An online device can receive commands from IoT Platform. If the device is offline, the device can request the cached commands after the device goes online.

Device shadows

NTP service Synchronizes the time in IoT Platform to devices.

NTP service

Gateways and sub-devices Connects the devices that do not have IP addresses to IoT Platform by using a gateway.

Gateways and sub-devices

Device distribution Allows you to burn information on devices in different regions. This facilitates business migration.

Device distribution

Monitoring and O&M Remote access Remotely controls and manages devices. -
Log uploading Uploads device logs in real time.

Log uploading

Over-the-air (OTA) update Updates devices by using IoT Platform.
  1. A device can obtain the update information that is pushed by IoT Platform and download the update package.
  2. The downloaded update package is written to the flash memory or ROM of the device and takes effect. Then, an OTA update is performed.

OTA update

Remote configuration Remotely updates the system parameters and network parameters of the device without stopping or restarting the device.

Remote configuration


Version number Description Remarks Reference
  • Reduces the requirements for RAM.
  • Reduces the dependencies between features.
  • Optimizes user experience of developing the SDK on different operating systems.
  • Supports SDK customization.
  • This SDK version is not compatible with the previous version in the API operations of some features.
  • You cannot connect devices to Link Living.
Notice This version of the SDK is regularly maintained and updated. We recommend that you use this version of the SDK.
3.x Provides a tool to extract code and modify features.
  • You can extract code based on your business requirements. This facilitates code porting.
  • This version of the SDK is no longer updated and does not provide some advanced features.
  • Adds some features of IoT Platform.
  • Requires the Linux compilation environment.
  • When you compile the SDK, you must use the method that is defined by Alibaba Cloud. Code extraction and porting are complicated.
  • We recommend that you do not use this version of the SDK.
1.x None We recommend that you do not use this version of the SDK. None