Nowadays, the transmission of data from remote field devices to SCADA systems for monitoring, control, and Internet of Things (IoT) applications, has become widespread. For the current state of technology, it is evident that field devices are having Ethernet communication capabilities.
When it comes to Ethernet (TCP/IP) communication via GSM data services, LTE router is needed to facilitate remote reading. Selecting the right router involves considering several key factors to ensure the solution is suitable. We hope you find this article, prepared with this in mind, useful.
Two architectures stand out when addressing router requirements: the standard router and the bridge router. By examining these two router alternatives in detail, it is possible to determine which offers the optimal solution for IoT applications.
Standard router functionality encompasses the hardware and software designed to operate under heavy work loads, incorporating features such as NAT and IP forwarding. The hardware must possess sufficient processing power to handle dynamic workloads, while the software must manage functions associated with such loads, including memory capacity and management.
The term "bridge mode" can carry different meanings depending on the network topology; however, the primary objective here for this article is to implement a monitoring and control application using a GSM data service. So we will examine the concept of a "bridge router" within the context of IoT applications.
First of all, it is useful to describe the industrial devices used in the field. Devices with Ethernet (or Wi-Fi) capabilities communicate via TCP ports. These ports typically appear as a single, predefined port value—such as port 20000 for DNP3 or port 502 for Modbus TCP.
When examining the communication protocols of these devices, inefficient transmission can occur during the transport of communication data. The TCP Maximum Transmission Unit (MTU) is 1,500 bytes, while the maximum payload size is 1,460 bytes. Within these limits, the payload size of the common industrial protocols is low relative to the MTU value(i.e 256 for Modbus TCP, 292 for DNP3 data link layer).
This inefficiency can be illustrated by a scenario where, out of 1,460 train cars, only 256 are loaded while the rest remain empty. Consequently, there is no need to transport industrial application data in big segment sized packets.
In this context, hardware memory requirements can be minimized by reducing packet sizes. This results in a much more efficient and cost-effective hardware.
In simple IoT architectures where a single device or a limited number of devices must be accessed over a specific TCP port, the need for NAT and advanced routing functions can be significantly reduced. The implementation is complete once remote bidirectional access to a TCP port is established; however, security requirements must be addressed at the device level through TLS, VPN tunnels, or dedicated authentication mechanisms.
Since the need for intensive routing operations is eliminated in this way, the hardware load and software complexity for the router are reduced, and the option to develop hardware precisely tailored to specific needs becomes available.
This option presents itself as a bridge router. In applications where remote access for only a single device is required, many features offered by standard routers may remain unused. Bridge router solutions, featuring a simpler architecture, can offer significant advantages in terms of cost, reliability, and manageability.
The GSM bridge router emerges as a solution that precisely meets needs, is robust, minimizes the risk of errors, and ensures optimal performance.
