E840-TTL Series 4G/LTE Data Transmission Module Product Introduction

The E840-TTL (4G05-DGC) wireless serial port module is an LTE data transmission module product launched by EBITE. It is developed to enable data transmission between serial devices and network servers via a network. The product boasts comprehensive software functionality, covering most common application scenarios. Users can achieve bidirectional transparent data transmission from the serial port to the network server with simple settings. Through simple AT commands, this product can easily achieve bidirectional transparent data transmission from the serial port to the network.

The wireless data transmission module uses a 2.0mm pin header interface, facilitating circuit integration for customers. It uses a wide voltage supply of 5V to 18V. It supports China Mobile, China Unicom, and China Telecom 4G cards. The communication signal and LED indicators use compatible levels, with a default of 3.3V, but can also operate at 5V. The module has strong anti-interference capabilities and is suitable for environments with strong electromagnetic interference, such as the power industry.

The previous article provided a quick start guide to the E840-TTL 4G/LTE wireless data transmission module, setting up a simple hardware environment to test the network transmission function of the E840-TTL (4G05-DGC), specifically enabling bidirectional data transmission from a serial device (referring to the computer) to a network server.

Features of the E840-TTL (4G05-DGC) LTE Data Transmission Module:

This 4G/LTE wireless data transmission module supports the MQTT protocol and can access OneNet, Alibaba Cloud, and Baidu Cloud platforms.

It supports transparent data transmission, TCP and UDP network protocols, and heartbeat and registration packet functions.

It supports bidirectional data transmission from the device to the network server at serial port baud rates of 460800 and below.

It supports large serial port buffering, allowing serial port data to be cached locally before a connection is established with the server.

It supports SMS sending and receiving, and remote SMS querying/configuration of device parameters.

It supports simultaneous sending and receiving of multiple socket links.

It supports Modbus RTU and Modbus... Automatic TCP protocol conversion;

The 4G/LTE wireless data transmission module supports remote querying/configuration of device parameters via network AT commands;

The 4G/LTE wireless data transmission module features a dual watchdog design (software and hardware), ensuring system stability and preventing crashes;

The 4G/LTE wireless data transmission module supports GPS and BeiDou satellite positioning for more accurate positioning and supports GPS/BD active antennas.

E840-TTL(4G05-DGC) LTE Data Transmission Module Precautions:

1. The first socket of the 4G/LTE wireless data transmission module must always be open. After successful initialization, it will automatically establish a connection with the configured network server.

2. If the wireless data transmission module fails to initialize successfully after power-on (i.e., the State indicator light shows no indication for more than 30 seconds), check if the module is installed correctly, if the SIM card is inserted correctly, and if the SIM card is invalid.

3. The short connection function can be used to reduce the connection pressure on the server from multiple devices. When the short connection function is enabled (AT+SHORTM>2), if there is no data transmission from the network or serial port for an extended period exceeding the short connection setting period, the module will actively disconnect the connection. After disconnection, the network cannot send data, but the local serial port sends valid data. The module will immediately establish a connection with the server. If the local cache clearing function is disabled, this data packet will be cached (maximum 10KB). After a successful connection, the data will be sent to the server. If the local cache clearing function is enabled, the data packet will be discarded.

4. The heartbeat function is used to maintain the connection after the wireless module successfully establishes a connection with the server. In the network, if there is no data transmission for a long time after the client and network server successfully establish a connection, the Socket link may "die," meaning the link exists but data cannot be sent or received. Therefore, in practical use, it is recommended to enable the heartbeat function to ensure the reliability of the network link.

5. In actual use, differences in data latency between two communications are normal.

6. When protocol transmission is disabled, this data transmission module supports a maximum single packet length of 10KB per link. Sending data packets exceeding this length via the local serial port or network may cause packet errors. With the distribution protocol enabled, each Socket link can support a maximum single packet length of 1024 bytes (user-configured serial port packet length).

7. In high-speed continuous transmission mode, EMBMAC and EMBCSTM registration packet functions cannot be enabled. Furthermore, SMS sending and receiving are not supported in high-speed mode; only the first valid Socket link is active, and protocol-distributed data is not supported.

8. When the device serial port outputs "pdp error, device will be reset!", it indicates that the PDP context has been disabled by the network, possibly due to a loose SIM card or abnormal network channel occupancy.

9. The SMS function requires an inserted SIM card that supports SMS services; IoT cards cannot send or receive SMS messages. When the device sends an SMS, the device's "OK" response only indicates that the module has sent the SMS, not that the device has received it.

10. When the serial port frame break time is modified, AT commands must also be configured to operate according to this frame break time. For example, if this parameter is set to 2000ms, upon the next power-on, to configure device parameters, a valid AT command must be sent within a time frame greater than 2000ms and less than 3000ms after sending '+++' to successfully enter AT mode.

11. Network AT commands will be ineffective in high-speed mode.