Off the shelf availability of Custom IoT Gateway
Any IoT implementation requires a gateway. Since most industrial gateways comes at a price above average, choosing a right gateway for your new IoT requirement could be a daunting task. With the advancement in IIoT, several segments of industry use cases are popping up and each with their unique requirements. For example, condition monitoring of a thermal power plant, predictive maintenance of factory heavy machinery and asset tracking of containers in a shipping yard etc. Every such requirement comes with their unique challenges for hardware and software.
Gateway for successful IoT implementation
In IoT architecture, a gateway basically acts as a bridge between sensors and cloud. There are several measures to choose and decide the architecture of node to gateway which is out of scope of this article. Sometimes, it is a combination of many node points aggregating data to a central gateway while sometimes many local gateways talk to a central gateway. The key terms while choosing gateway for your application is as following:
Edge computing are becoming popular with IoT advancement as it decreases network and cloud load. It allows data processing at the very beginning of IoT architecture. This selection is very much needed when complex calculations are involved from data. Embedded controllers advancement allows complex calculations to be done faster. If there is no field constraints such as power or implementation feasibility, then edge gateway should be ideal choice.
Mainframe Linux vs Embedded Linux
Using mainframe Linux is a good choice for IoT Gateways as it eases configuration and system upgradation. For example, if ubuntu or any other mainframe linux could be installed on SBC (Single Board Computer) of choice then only complexity will be setting of embedded protocol at driver level. Once the raw data is available, then application programming becomes easy with any language of choice such as Python, C or Java. Embedded Linux are customized Linux version where yocto project comes in picture. Yocto provides abstraction layer independent of hardware architecture and eases development for Embedded and IoT software requirement.
Hardware chip level architecture
Looking from hardware architecture perspective, ARM & Intel are two major names. ARM based gateways are comparatively cheaper because of wide adoption by industry and semiconductor players. Particularly i.MX series of SoC (System-On-Chip) is being released from Freescale and widely used for designing IoT gateways.
A good gateway provides a good debugging capability. During the initial development of the solution, it is inevitable to make changes in program many times. Generally, an IoT gateway comes without any display interface so other interfaces debugging capability helps in reducing time-to-market.
As the complexity of IIoT practice increases, different types of sensors need to be used which need different interfacing options available at IoT gateway. However, most sensors comes with analog output so first thing to look for in a gateway is ADC interfacing. Apart from that different digital interface options can be looked at such as I2C, SPI & UART.
Configurable and enhanceable
Gateways should always be made as configurable and enhanceable as possible. It should have compatibility for moving from prototype to production version. It should also allow hardware compatibility upgradation such as addition of SPI or CAN interfacing as per requirement.
Both RAM and Flash memory plays an important part of the overall requirement. As the number of sensors increases, there are chances of sending bigger string size of data at a time. This requirement need enough RAM size, so it is better to design string requirement at the very first place and then look for RAM size accordingly.
What are the offerings from major HW vendors?
This article gives a very extensive comparison of latest offerings on gateway from major players. However, rather than putting just a computer in the field, you need a device which can accept sensor data at minimal cost and without the need of additional hardware. Most of the devices listed here are generic and accept standard protocols such as UART, I2C, SPI and CANBUS etc. Meeting such additional protocol requires additional MCU hardware interfacing in order to accept raw sensor data and transfer it over some other standard protocol. These additional requirements results in additional cost.
Points to design your own gateway
Irrespective of whether you get your requirements fulfilled from hardware players, there is a great chance of missing some or other feature. This is the point where you should consider designing your own gateway.
Most analog sensor come with analog output and it is crucial for the gateway to support ADC input with decent resolution as well as sampling frequency. Most gateways comes with multiplexed ADC channels so there is delay between sampling from successive channel. If speed of sampling is very much crucial for your requirement then you definitely need to put different ADC chips for different channels. This way sampling will be done in parallel and obtained raw data will faster as needed for real time implementations. Apart from this all points for choosing the right gateway will be applicable in designing your own gateway.
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