For charging pile manufacturers, it is not difficult to produce the hardware itself. The real trouble lies in how to achieve stable network connectivity after the equipment is delivered in batches.

Charging piles located in public parking lots, highway service areas, industrial parks and community underground garages are often widely scattered. If each site relies on broadband cabling, not only will the construction workload be huge, but the network will also need to be reconfigured when adding new pile positions later. Underground garages and remote stations frequently face problems such as weak signals and drastic ambient temperature changes. Once the communication is interrupted, it may affect the upload of device status, order generation and background reconciliation.

This is a very common application scenario for cellular modems in charging pile projects.

Take the USR-G771 as an example. The cellular modem connects to the main control unit of the charging pile, electricity meters and other devices through RS232 or RS485, and then transmits serial port data to the operation platform via the Cat.1 network. It is equivalent to establishing a wireless data channel between the charging pile and the background. The official documents also list the upload of charging pile operation data to the cloud server as one of its typical applications.

What problems actually need to be solved for charging pile networking?
1.1 The on-site network conditions are difficult to unify.
A manufacturer may deliver projects in shopping mall parking lots, underground garages and highway service areas at the same time, and the network conditions of different projects are completely different. After adopting a cellular modem, as long as there is cellular network coverage on site, the charging pile can connect to the network independently, reducing the dependence on the owner's local area network and fixed broadband.

1.2 Ensure that charging data can be continuously uploaded.
A complete charging process will generate data such as start, stop, electricity consumption, operation status and faults. These data need to be uploaded to the operation platform so that the platform can further complete order processing, billing and reconciliation.

Here is a concept that needs to be clarified: a cellular modem is not a settlement device.
The calculation of charging fees, order processing and payment success are still completed by the charging pile control system and the operation platform. The cellular modem solves the intermediate communication problem — it enables these data to be transmitted from the on-site equipment to the background, and sends the control instructions issued by the platform back to the charging pile.

The G771 supports communication methods such as TCP and UDP, and supports data transmission between the serial port and the network. It also has mechanisms such as multiple Sockets and data caching. For manufacturers, it is more suitable to be used as a communication interface for the existing charging control system, rather than developing a completely new networked controller.

How to deploy a cellular modem solution for charging piles?
The typical link can be understood as:
Charging Pile Main Control Unit / Electricity Meter → RS485 or RS232 → Cellular Modem → Cat.1 Network → Charging Operation Platform → Order and Settlement System

During the equipment design phase, reserved positions for the cellular modem, DC power supply and serial port interfaces should be set aside inside the charging pile control cabinet.

① First complete the serial port connection between the main control unit and the cellular modem.
Confirm whether to use RS485 or RS232, and unify the baud rate, data bits, stop bits and parity check method. The official specifications of the G771 support RS232, RS485 and baud rates from 1200 to 230400 bps. (pusr.com)

② Configure network parameters
These include the platform server address, port, communication method and device registration information. Different charging piles are distinguished through registration packets, and the heartbeat mechanism is used to judge whether the device is online.

③ Install the SIM card and antenna.
After powering on, first check whether the cellular modem has successfully registered to the network, then confirm from the background that the corresponding device is online.

Finally, be sure to run a complete business process: start charging by scanning a code or swiping a card, generate electricity consumption data, end charging, upload the order, and then check whether the background order, electricity consumption and device status are consistent.
Only when this entire process runs smoothly can we confirm that the "networked settlement link" is truly established.

What is most easily overlooked in batch deployment?
3.1 Antenna position.
The charging pile itself is a metal cabinet. If the antenna is placed deep inside the cabinet, the signal may be normal when the cabinet door is opened for on-site debugging, but frequent disconnections will occur after the door is closed. This problem is particularly prominent in underground garages. Therefore, it is best to test the signal in the final installed state, and use an external antenna if necessary.

3.2 Do not equate automatic reconnection after disconnection with no lost orders.
Cellular modems can improve communication reliability through reconnection and caching mechanisms, but for key data related to charging fees, it is still recommended that the main control unit of the charging pile or the platform design local caching, order numbering, confirmation response and abnormal retransmission mechanisms. Communication equipment can only reduce the risks caused by network disconnections, and cannot replace the data integrity design at the business layer.

3.3 Do not deploy the entire batch directly for large-scale projects.
It is recommended to first deploy several prototype units respectively in ground parking lots, underground garages and weak signal areas, and run them continuously for a period of time. Focus on testing disconnection and reconnection, platform disconnection, device restart, weak network conditions and the complete charging order process.

3.4 Confirm the product version.
Different regional versions may support different cellular frequency bands. The G771-E is LTE Cat.1 compatible with GSM, with a working voltage of 9 to 36V and a working temperature range of -30 to 75℃. In actual projects, the corresponding model should be reconfirmed according to the sales region and the local operator.

For charging pile manufacturers, the value of cellular modems does not lie in adding a large number of complex functions, but in isolating the communication part that was originally easily affected by on-site network conditions.
If the original main control unit already has serial port communication capabilities and the data protocol can directly connect to the operation platform, adding a cellular modem usually does not require major modifications to the original hardware architecture. By fully verifying details such as serial ports, networks, antennas, abnormal reconnection and order retransmission before mass production, subsequent batch delivery and remote operation and maintenance will be much more convenient.

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