What are convenience stores most afraid of? During peak hours, the circuit breaker suddenly tripped, the POS machine (cash register) restarted, and the machine started to smoke during the checkout process. The root cause of these problems is oftenVoltage in old stores is unstable——The startup and shutdown of high-power equipment nearby and the peak power consumption of air conditioners in summer will cause the voltage to fluctuate.

The idea behind this plan is:Use intelligent hardware to monitor the voltage, automatically cut off the power when abnormal, and automatically reset when normal. No manual intervention is required throughout the process, and all data is uploaded to the cloud.

1. What pain points do we want to solve?

• Burn the machine:The voltage suddenly jumped above 250V, and the cash register power board burned out.

• Data lost:When the voltage is low and the machine restarts, the inventory data being entered is not saved.

• No one is here:The circuit breaker tripped in the middle of the night, and the boss had to run all the way to flip the switch.

• No record:Why did it trip? have no idea. How to prevent it next time? No clue.

2. Core logic (a little technical, but easy to understand)

Let's add one in front of the cash registerSmart socket/strip with power metering function, which is connected in series between the power grid and the cash register.

This socket can report voltage data to Thingboot Cloud in real time, and we set the "protection threshold" in the background (for example, overvoltage 245V, undervoltage 180V). When the cloud or local logic determines that "voltage is abnormal", an instruction is issued immediatelyTurn off the outlet switch, cut off the power within 0.1 seconds; wait for the voltage to return to normal and stabilize for a period of time, and then automatically close and send power.

In order to prevent the network from being disconnected, it is best for the device to support "local automatic control" - even if the network is disconnected, it can trip itself as long as it detects a voltage abnormality.

3. What hardware is required? (What to wear when going to the store)

• Smart metering socket/PDU:Thingboot’s smart socket series, 86-type wall socket or desktop PDU. Select beltPower metering function(can read voltage and current), this is the core. This socket is our actuator for controlling on and off, and it is also the sensor for voltage sampling..

• Cash register (POS machine):Just plug it into the back of this smart socket and you don’t need to change anything.

4. Software docking: How to control it with code?

We need to write the "protection logic" into the background or small program through Thingboot's open interface.

A. Step one: Read the voltage (although it is usually reported proactively, you must be able to check it)

Scenario:Your server wants to see what the voltage is now and decide whether to protect it.Action:Call core stepDevice attribute query interface(Or it pushes it proactively, depending on the mechanism you set up).Concepts involved:You need to monitor what the device reportspowerRelevant parameters, there will bevoltage(Voltage),current(current) field.

B. Step 2: Issue instructions (core action: cutting/closing)

Scenario:If an extremely high voltage is detected, power off immediately!Action:Call the device control interface.

Interface example (refer to official documentation):

• URL:http(s)://api.thingboot.com/{Your AppID}/device/control/?sign={Signature}&ts={Timestamp}

• Way:POST (JSON format recommended)

• parameter:

citation[1]

Advanced gameplay:If the device supports the "reset/restart" function (disconnect first and then connect), you can useresetcommands, such as{"reset": 60000}, meaning disconnection and automatic recovery after 60 seconds.

C. Step 3: Create automatic control logic (what does the cloud brain think?)

You can't ask "What's the voltage?" every second, that would be too tiring.It is recommended to use the "event triggered" mode:The smart socket detects voltage changes locally and actively pushes them to the cloud platform; after receiving the data, the cloud platform determines and automatically calls back the interface if it needs to trip.

Logic pseudocode (written in your business system):

5. Three steps to implement the plan

Step One: Network Distribution and Installation

Plug the smart socket into the power cord of the cash register (or replace the original wall plug with the 86 box). Use Thingboot’s App to configure the network for the socket (connect to the 2.4G Wi-Fi in the store).

Step 2: Set protection strategy (key parameters)

Set parameters in the background system. According to the convenience store cash register (the adapter generally has a 12V/5V output, and the input withstand voltage is in a wide range of 100-240V, but the settings are stricter):

• Overvoltage cut-off value:245V (if the power grid often fluctuates, it can be set to 250V).

• Undervoltage cut-off value:175V (although the computer power supply can support it, the high current is bad for the life of the power supply).

• Delayed recovery:After the voltage returns to normal (190V-235V),Delay 30 secondsPower on again. These 30 seconds are to prevent the voltage from falling again as soon as it recovers, causing the relay to trip repeatedly and damage the machine..

Step 3: Alarm and reset

• Alert:When tripping, send a message to the boss WeChat/DingTalk through Thingboot's API message push: "[XX Convenience Store] The voltage is too high and the power has been cut off. Please check."

• Remote reset:After the boss receives the message, if he wants to try to force the power to be sent, or confirm that everything is OK, open the management APP, click "Open", and call{"power": 1}instruction.

6. What is the advantage of this solution? (Selling point for the boss to see)

1. Unattended:There is no need to ask an electrician to keep an eye on it, it will turn on automatically when the voltage is high.

2. Protect data:Sudden power failure will damage the hard drive. This is cut off when the voltage is unstable, and will not allow the hard drive to "survive" under low voltage and cause bad sectors.

3. quick:HTTP interface call, response time is approximately80-120 milliseconds, in the blink of an eye, before the light flashed, the electricity went off, faster than a fuse.

7. Precautions (Guidelines for Preventing Pitfalls)

• Equipment selection:Ordinary smart sockets that cost tens of dollars only have a switch function.Must choose one with metering function, to read the voltage. There are several Thingboot models with power metering, please remember to confirm the model number..

• Disconnection situation:If the Wi-Fi is disconnected, the cloud’s judgment becomes invalid. Best to supportLocal timing or threshold triggerfirmware version. If not, at least make sure that the cash register's own power adapter is of high quality and can withstand fluctuations.

• High power issues:The power of the cash register is not high (usually tens of watts), but if a microwave or freezer is plugged into the socket, be sure to check the maximum power of the socket (usually 10A/2500W).Never plug your freezer and cash register into the same smart socket, the pressure drop when the freezer compressor starts will trigger a misjudgment.

To summarize:Take Thingboot’s metered smart socket and connect it to/device/controlInterface, write a voltage judgment script. If the voltage is abnormal, it will occur.power:0, just send it normallypower:1. Done.