FAQ for NB-IoT Devices

How to associate the NB module?

• Before bundling the NB module, please make sure the NB module is equipped with a minimum system circuit. The power supply is stable, the signal strength of antenna compliance is good, and the NB IoT SIM card is inserted.

• The NB module is not activated until it is used for the first time after it is shipped from the factory, so using the Tuya Smart App to associate it will fail.

• Module activation steps

  1. The module is powered and the MCU interacts with the module
  2. The module will send 01 command word to MCU to query the product PID
  3. MCU replies to the product information query command sent by the module
  4. The module receives the product information and uploads it to the cloud for module activation
  5. the module replies with the network status 03 (connected to the telecom platform, the device is not bound)
  6. At this time, you can use the Tuya Smart App to scan the module shortcode tag to associate the device

• Tuya MCU Emulation Assistant test data.

• Tuya Smart app operation. For detailed instructions, see user manual of App-in-one app.

  Note: Module short code tag is the unique identification code for Tuya NB module, not the module’s own production tag, which is generally affixed to the outer packaging of the whole machine for the convenience of end-customer binding use. This label must be generated using the Tuya label printing tool, which can be obtained from Tuya technical support. During the development phase, the module IMEI binding can be entered manually.

  • After the App is bound, the device side must interact with the Tuya IoT once before the binding message can be synchronized. This can be done by actively reporting a piece of data or by the MCU sending a reset command to the module to interact with the Tuya IoT. A successfully synchronized module will send a notification of the bound network status.
  • NB modules are strongly bound and once they are bound by a user, they must be removed from the device via the App before other users can be bound. Local reset command on device side cannot unbind.

How to report data for modules?

• When PSM type module reports data, it must exit PSM mode. The module can be woken up by pulling down PSM_EINT for more than 5 ms (the specific time is based on actual measurement). The 05 command word - Real Time Data Reporting or 08 command word - Recorded Data Reporting (recommended) can be used at this time.
• The DRX type module can respond to the report command from MCU in real-time.
• If the module is not bound, the reported data will be filtered out locally and will not be uploaded to the cloud, and will be returned to the MCU for reporting failure.
• For more details on the use of 05 and 08 command words, please refer to General Protocol.

How to view the logs sent up and down from the device?

• After successful network distribution, if you want to see the backend data sent from the device, you can log in IoT Platform Product Management and query according to device ID, module SN number, device name, etc.
  
• Device ID, which can be viewed on Device Log Page after the network is configured.
  

What do I need to pay attention to regarding combo reporting?

• The NB module supports combined reporting, please check the docking protocol for the format. One frame of data should not exceed 255 bytes.
• It is recommended to use combo upload for more than 2 DPs per upload to save upload time and power consumption.

What should I do if I can’t receive the sent data?

PSM type terminal is deeply dormant during the non-service period and does not receive downlink data. Only the downlink data cached by the IoT platform can be received when the terminal actively sends uplink data (MO Data).

• The App panel operates to send commands, but the module does not send the downlink data. This is because the NB module is in PSM low-power mode, which turns off peripherals such as RF reception and cannot receive data. The module must actively report the data once to interact with the Tuya IoT once, and the last operation lagged to issue the downlink command. Multiple DP points operate, multiple data will be sent down, and the same DP point will only send down the latest operation.
• When the heartbeat interval cycle set by the module arrives, the module will automatically and interact with the platform once to maintain the heartbeat, and the cached data is sent down at this time.
• If the device is offline, all downgoing commands cached by the platform will be cleared.

Is it possible to send data every time the app operates?

• Yes, you can use DRX mode NB module, and use SIM card with DRX service.
• The DRX type NB module does not enter PSM state, so the sent data is received in real-time.
• PSM type NB module does not support real-time downlink, which is determined by NB characteristics.

How to unbind NB modules?

• Cloud side: After removing the device on the App side, it can be bound by other accounts, and it doesn’t matter if the device side is not synchronized.
• Device side: After the device is removed, the network status of the module still shows bound, and you need to interact with Tuya IoT once to synchronize the unbinding information.
• The following ways can be used to synchronize.
  • Report data once and interact with the platform once. The module then shows a reported failure and the network changes from bound to unbound (recommended).
  • The MCU sends a reset command to reset the NB module.

About the use of reset command?

• The reset command, used to restore factory settings, will reset the module’s local heartbeat interval to the default 8h. The MCU sends this command to the module, and the module will go to the cloud to re-download the product information (only when the device is unbound).
• If the product PID is changed, or some DP points are modified, the module needs to update the product information. So it needs MCU to send a reset command to the module, and the module will execute restoring factory settings and go to the cloud to update the current product information at the same time. It needs the device to be unbound to take effect.
• MCU tries not to call this instruction in the program, this instruction will make the module report the current product PID and update the product information from the cloud. More interaction data affects power consumption and traffic. The process of downloading the data related to product information is a bit long, about ten seconds, and reporting data to the module during this process will be judged as a failure.
• A physical button can be added to the device to trigger the MCU to send a reset command to the module to update the product information.

How does the sleep lock work?

• When the sleep lock function is enabled, the module will turn off the function of entering PSM, i.e. in the idle state. The module does not enter the low-power state and can respond to the commands sent by MCU in real-time, so it does not need to wake up the module by PSM_EINT to respond to the commands sent by MCU.
• PSM type SIM card: If a large amount of data is reported every time the module wakes up, and the packet interval is long. To avoid the module entering the PSM low-power state before the data is sent, the sleep lock can be turned on after the module wakes up, and then turned off after the data is sent (according to the actual demand).
• DRX type SIM card: The MCU should open the sleep lock after the basic interaction with the module to prevent the module from going into light sleep (required).

How does the App show that the device is offline?

• By default, the cloud logic determines that the device is offline if no data has been reported for more than 24 hours (consistent with Telecom cloud logic).
• The detection cycle time is not full, or the device is disconnected, the cloud still shows online.
• If there is a special need to change the cloud offline detection time, you can communicate with the project manager and the cloud will reset the cloud offline detection time for this product (more used for DRX type requirements).

What do I need to pay attention to regarding the module heartbeat interval?

• This heartbeat is the heartbeat cycle of the module and the platform. The default heartbeat interval of the module is 8 hours, and the minimum is 1 minute, there will be problems if the setting is lower than 1 minute.
• This heartbeat can replace data reporting and maintain the online status of the device.
• One heartbeat of the module consumes about 96 Byte of traffic to interact with the cloud.
• If you want to avoid traffic loss due to frequent heartbeat reporting, you can set the heartbeat interval to tens of days, hundreds of days, or set it to 0 to turn off.
• When the network is very poor, the module will go into a deep sleep (non-PSM mode) when it fails to send, and the heartbeat function will be turned off and the module must be woken up by pulling down PSM_eINT.

How long does it take for the NB module to reenter PSM mode after waking up?

After the NB wakes up, it takes at least 20 seconds to enter the low-power state again. The specific time is related to the signal strength and the type of APN handled by the SIM card.

If the terminal has not received and sent data within this timer time, the base station will release the wireless connection of the terminal (the user session information of the core network is maintained and the IP address of the terminal remains unchanged), and the terminal will enter the Idle state and activate the timer. Idle state and activate the activation timer (Active-Timer). When the activation timer times out, the terminal enters the PSM state.

NB enters PSM after waking up for more than 20 seconds, is this time too long, and can be set?

• No, this time is designed according to the original chip manufacturer’s recommendation, 20 seconds can guarantee the stability of the network link, and the standard NB is fixed at 20 seconds or so, which is decided by the core network of the base station and the module firmware.
• The firmware can be customized to be smaller, but it may lead to incomplete access to the downlink rate and data transmission. It is used for devices without downlink control. Please consult your project manager for details.

What are the considerations for the signal strength of NB?

• MCU can check the signal strength of the NB module by command, if the signal strength is within 10, it means the signal strength is very poor, and it is possible that it cannot connect to the operator’s base station.
• Please check whether the SIM card is activated, whether NB service is applied, whether the tariff does not exceed the marked amount, and whether the installation is correct.
• The signal strength is related to the antenna performance of the base station coverage and the device. If the signal strength is very poor, please check whether the antenna is a good antenna with matching and whether the contact is poor.

What is the power consumption of the NB module?

How to select SIM card for NB module?

• The NB module of Tuya supports three networks, and the commercial platform of Tuya is Telecom, so it is recommended that the SIM card is preferred to Telecom, followed by Mobile (there are hidden dangers).
• You can purchase an NB IoT card from your own carrier, please make sure whether the APN is PSM or DRX supported card when you purchase. You can also buy from Tuya, please contact the account manager for tariff package details.

What are the service types of NB modules?

• There are two types of NB modules in Tuya: PSM type and DRX type. The two types correspond to two different types of cloud logic. Please make sure the business type of the product before applying for the module.
• PSM type module will enter PSM mode to reduce power consumption, commonly used in battery-powered devices, fixed reporting notification type, not real-time response to the issued instructions.
• DRX type module, will not enter into low power consumption, real-time response to up and down data, commonly used in power-insensitive devices, real-time control type.

How to use DRX type NB module?

• Use IoT SIM cards that support DRX type
• IoT platform to create DRX type products
• Use DRX type module firmware
• Module must call the sleep lock command after waking up to prevent going into lightsleep, if not open the sleep lock, there will be problems in this state of communication.

NB platform, does it support alarm notification messages such as SMS and phone call?

Yes, but it’s a value-added service and requires an extra charge, please contact the project manager for details.

Can the NM1 module be used directly overseas?

No, this module can’t be used outside mainland China.

Does the NB module support positioning?

No. The network module supports R14 protocol standard, the carrier does not support location function for the time being, pending the carrier’s subsequent opening.