Preface

Our previous article- " Why do you need a data collector from RS485 to LoRaWAN ? " introduced the advantages of a data collector from RS485 to LoRaWAN.

Specifically, in industrial scenarios, there are more and more sensors. Because they do not have convenient power supply methods and require long-distance transmission, more and more low-power wide area network technologies are adopted, of which LoRaWAN is a standard. The technology, with the attributes of flexible networking and local management, has been adopted by more and more industrial applications.

However, compared to the ideal industrial scene, we see that the standard LoRaWAN protocol still has many limitations. For example, if the data to be transmitted exceeds 51 bytes and exceeds the LoRaWAN protocol specification, this situation greatly limits the application. Therefore, how to break through the limitations of the LoRaWAN protocol is to meet the needs of an actual industrial scene. RS485 collection The device is a problem we have seen in practice.

In actual industrial applications, some people may think that the RS485 to LoRaWAN data collector is not easy to use, or actually cannot be used. What is going on here?

This is because there is no improved RS485 to LoRaWAN data collector, which is indeed limited in application and is not suitable for all industrial application scenarios.

Therefore, when we select RS485 to LoRaWAN data collectors, we cannot choose with our eyes closed. We need to focus on what improvements have been made to these data collectors and what functions they have.

This article introduces some inherent shortcomings of common RS485 to LoRaWAN data collectors, and introduces which elements should be focused on when selecting RS485 to LoRaWAN data collectors.

1. Some inherent defects of ordinary RS485 to LoRaWAN data collector

1. Some devices have a large amount of data, which exceeds the byte limit of the LoRaWAN protocol

Although, in industrial application scenarios, the use of RS485 to LoRaWAN can bring a series of benefits, such as wide coverage of LoRaWAN gateways, simple networking, low power consumption, but in practical applications, some special industrial application scenarios are It is not possible to directly apply RS485 to LoRaWAN data collector .

For example, some industrial sensors do not consider the need for wireless transmission of data, and the amount of data will be relatively large. For example, in some application scenarios such as vibration sensors or radar detection, the data that the sensors need to transmit often reaches as much as 1K bytes, and the LoRaWAN protocol can transmit The data is only 51 bytes. Therefore, in the above-mentioned special industrial application scenarios, the ordinary RS485 to LoRaWAN data collector will not be able to discard the data because the data exceeds the limit, making this type of sensor unable to use lora technology to transmit data .

2. Sensors need more control commands, which will cause network congestion and insufficient bandwidth

Most sensors in industrial application scenarios, such as industrial field temperature sensors, require a few seconds to upload data regularly.

If you follow the common transparent transmission method of 485 to LoRaWAN to transmit data, then the LoRaWAN gateway needs to first issue instructions to the data collector, and then the data collector issues the instructions to the sensor, and then the sensor receives the query instruction, and then Upload the sensor data. It can be seen that in the whole process, every time sensor data is to be uploaded, a lot of downlink bandwidth must be occupied to issue instructions. In the LoRaWAN network, there is only one downlink channel (upstream 8 channels), and too many downlink reports. Text will cause network congestion and data cannot be transmitted normally.

3. The device cannot be remotely managed, configuration parameters

In actual industrial applications, equipment is usually installed in areas with restricted operations and cannot be easily configured and maintained locally, so remote equipment management capabilities are required.

For example, if you want to change the acquisition frequency of a certain sensor, if you cannot configure the device remotely, you need to apply to the industrial site to modify the command of a certain terminal device through the configuration line without affecting production.

However, for terminals that support remote configuration, configuration commands can be issued to the device through the LoRa network, without the need for maintenance personnel to go to the site and interrupt production.

In addition, after supporting remote configuration management, not only can the configuration of multiple devices be modified at the same time, but also the configuration can be modified regularly according to production requirements, which can be automatically completed by connecting with the background server.

2. Several factors that need to be considered when choosing a data collector from RS485 to LoRaWAN

In order to ensure that the purchased RS485 to LoRaWAN data collector can meet the needs of actual industrial application scenarios and avoid problems that are found to be unusable or unusable after purchase, we need to do our homework before purchasing.

The elements that need to be examined before buying include the following aspects.

1. Is there a data subcontracting function?

The advantage of subcontracting is that it does not need to be restricted by the packet length stipulated by the lorawan protocol, and can connect to some devices with relatively large data volume. In this way, it is possible to get rid of the 51-byte limitation of the LoRawWAN protocol.

However, it should be noted that it is necessary to know the amount of data that the sensor needs to transmit each time in a specific application, and compare it with the maximum amount of data that can be transmitted after the data is packetized. Therefore, after data packetization is adopted, the amount of data that can be transmitted is not unlimited. For example, RAK7421, the data collector RAK7421 from RS485 to LoRaWAN, corresponds to the maximum amount of data of a single sensor of 1024 bytes, although compared to The 51 bytes that can be transmitted by traditional technology has been greatly improved, but it is still limited, not unlimited.

2. Is there a function of storing instructions and issuing instructions or polling regularly?

The function of storing instructions needs to be combined with, for example, timing functions to achieve the purpose of issuing instructions to the sensor regularly, or polling the sensor so that the sensor can upload data regularly.

For example, when the LoRaWAN gateway does not issue instructions, the data collector RAK7421 can also issue instructions to the sensor regularly, and it can also poll, so that the sensor can still upload data regularly. Thereby, the number of times the LoRaWAN gateway issues instructions can be reduced, bandwidth can be saved, and network congestion can be solved .

RAK7421 can automatically synchronize the network time. After setting a timing task, you can execute related commands at a specified time, query sensors or operate control switches, etc.

3. Is there a function of remotely issuing Modbus commands and remote configuration parameters?

The RAK7421 RS485 to LoRaWAN data collector has the ability to remotely issue Modbus commands and remotely configure terminal equipment. It can realize remote unified scheduling and management of equipment through docking with the user control platform, which is convenient for the maintenance and management of sensor networks, and reduces on-site configuration. Workload. It is also possible to edit a customized control process according to the user's business logic through this remote configuration capability to realize a customized solution.

Conclusion

When selecting a data collector from RS485 to LoRaWAN, you need to focus on several elements, such as whether it has the function of data subcontracting, whether it has the function of issuing commands regularly, whether it has the functions of remotely issuing Modbus commands, and remotely configuring parameters. Only in this way can we choose a data collector that really suits the needs of specific industrial applications, and enjoy the convenience of RS485 to LoRaWAN networking.

What points should be paid attention to when buying a data collector from RS485 to LoRaWAN?