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The Difference Between IoT and M2M Communication and Design

By Majeed Ahmad

Contributed By Digi-Key's North American Editors

Though related, machine-to-machine (M2M) communications and the Internet of Things (IoT) are different, yet are often used synonymously. This leads to misconceptions and confusion about their distinctive characteristics, capabilities, and design and implementation requirements.

This article explains the differences between the two and introduces examples of each approach before elaborating on M2M’s uniqueness relative to IoT systems using design solutions from Multi-Tech Systems, FreeWave Technologies, Hirschmann, and B+B SmartWorx. It also looks at new M2M capabilities such as over-the-air (OTA) updates and multi-layered security that boost network functionality and lower barriers to entry. Finally, it instructs designers on choosing the right M2M data plan to lower the data communication cost.

The difference between M2M and IoT

While both M2M and IoT technologies are about data sharing and links that drive data transfer, they are also different: IoT is a network of devices that are connected to the internet while M2M is a process of communicating among two or more electronics-enabled systems (or machines or devices) in an automated manner. The machines or devices in M2M point-to-point or point-to-multipoint connections can be sensors, actuators, embedded systems, or other connected elements.

Here, it’s important to note that M2M has been around before the term IoT was coined and before the emergence of the commercial internet in the mid-1990s. The origin of M2M can be traced back to telemetry applications that emerged after the advent of two-way radio in the early part of the twentieth century. However, the launch of GSM, the first digital cellular network, brought a new phase of development to M2M communications in the 1990s.

A decade or so later, the IoT emerged as a primary vehicle for connecting things via open IP-based networks. It was then that the dividing lines between these two unique communication technologies started to blur. To appreciate this blurring of lines, it’s useful to take an example application—in this case a heart rate sensor—and see how it fits into both the M2M and IoT models.

When a sensor monitoring the heart rate of a patient is connected to an external device or medical-grade server to keep the doctor informed about the patient’s health, it could be achieved via an M2M application. If, instead, the heart rate sensor is integrated into an interactive device proximal to the patient that sends alerts to a patient’s doctor or family members on their smartphones, it enters IoT territory.

M2M applications employing wired, wireless, and cellular connectivity mechanisms include automated reading of utility meters, intelligent connectivity with traffic lights, and surveillance camera-based home security and assisted living. It is at this networking technology crossroads that M2M communication starts to converge with similar IoT designs.

How IoT complements M2M

In a wider context, M2M communication has entered a new phase in the IoT era. As IoT’s cousin, M2M can use the same rapidly advancing connectivity technologies and solutions that are associated with the IoT, especially with regard to wireless. Multi-Tech Systems’ MTC-H5-B01-US-EU-GB MultiConnect Cell 100 Series cellular modems, supporting both M2M and IoT applications, are a case in point (Figure 1).

Image of MTC-H5-B01-US-EU-GB cellular modem from Multi-Tech SystemsFigure 1: The MTC-H5-B01-US-EU-GB cellular modem (left) from Multi-Tech Systems, designed for M2M applications, can also be used for IoT services. (Image source: Telit)

These cellular modems support GSM through to Cat 4 and Cat-M1 4G networks and are useful for M2M applications such as process automation, emergency services, remote patient monitoring, renewable energy systems, and end-of-train system management.

The Cell 100 Series modems offer several interface options, including RS-232 and USB serial interfaces, serving a broad range of application requirements. The hardware is supported by the MultiTech Connection Manager, a software package that automatically detects USB and serial devices, downloads required drivers, and ensures that communication ports are correctly mapped to establish an M2M connection.

As vendors work on low-power IoT solutions using highly integrated connectivity, this is also helping to facilitate compact M2M radios that are available with a variety of voltage inputs and network configurations.

A good example are the MM2 Series of 900 megahertz (MHz) RF modules from FreeWave Technologies. These can operate as an end point in both point-to-point and point-to-multipoint network topologies. The RF front-end modules incorporate a gallium arsenide (GaAs) FET and multi-stage surface acoustic wave (SAW) filtering for a combination of high sensitivity and overload immunity. Data rates are selectable: either 115.2 kilobits per second (kbps) or 153.6 kbps.

Typical specifications for the MM2 Series for output power, input sensitivity, and range are 1 watt, -108 decibels referred to 1 milliwatt (dBm), and up to 20 miles, respectively. The range assumes a clear line of sight.

M2M security and reliability

Security and reliability, traits shared by M2M and IoT designs, are even more critical in M2M applications as they usually don’t involve any human interaction. In fact, security and reliability are key hurdles in the widespread rollout of M2M networks.

So, in the wired space, Hirschmann’s RS20/RS30 industrial DIN rail Ethernet switches allow engineers to configure M2M networks according to reliability needs. The RS20 switches offer four to 25 Fast Ethernet ports to ensure extremely high failure tolerance (Figure 2). Likewise, the company’s RS30 switches feature eight to 24 port densities with two Gigabit Ethernet ports and eight, 16, or 24 Fast Ethernet ports.

Image of Hirschmann RS20 Ethernet switchFigure 2: The Hirschmann RS20 Ethernet switch offers four to 25 Fast Ethernet ports to minimize the chance of failure. (Image source: Hirschmann)

Fast Ethernet and Gigabit ports can be individually defined, which provides M2M designers with a choice to pick redundancy protocol and security mechanisms according to specific design requirements.

The support for standards like Media Redundancy Protocol (MRP) and Multiple Spanning Tree Protocol (MSTP) ensures high network availability for reliability conscious M2M applications. Similarly, there are numerous security mechanisms that these industrial Ethernet switches support, including IP and MAC port security, SNMP V3, SSHv2, and 802.1x Multi Client Authentication.

On the wireless front, B+B SmartWorx’s AirborneM2M Ethernet routers and bridges offer both single and dual serial port models to bolster the reliability of M2M applications (Figure 3). The dual port devices from B+B SmartWorx can establish Wi-Fi connections over both 2.4 gigahertz (GHz) and 5 GHz bands. Therefore, when the 2.4 GHz band is overcrowded with competing wireless communication activities, the M2M routers and bridges can keep data flowing by switching over to the 5 GHz band.

Diagram of M2M devices linked over Ethernet or serial linksFigure 3: A view of how M2M devices can be linked over Ethernet or serial links using highly secure Wi-Fi bridges and routers. (Image source: B+B SmartWorx)

The AirborneM2M networking devices also incorporate a multi-layered security approach that encompasses wireless security in the form of 802.11i/WPA2 Enterprise certification and network security with Extensible Authentication Protocol (EAP) certification support.

These M2M devices bolster network security by featuring the Secure Shell (SSH) public key authentication and fully encrypted data tunnels. Additionally, at the device level, these M2M routers and bridges offer multilevel encryption capability to protect configuration data.

When it comes to M2M services using cellular connectivity, security and authentication are usually baked into the LTE standards. In regard to physical security, eSIMs soldered directly onto the board make it nearly impossible for anyone to tamper and remove the SIM for misuse.

The SIMs used in M2M applications bring us to the final topic: M2M data plans and pertinent questions regarding their selection and usage.

M2M data plans

M2M designers and users may have many options when it comes to M2M data plans, as all major mobile operators offer data plans and pricing packages for M2M services. However, there are some key criteria under which to evaluate them, including degree of customization for the application.

Also, some subcarriers specialize in M2M services, and they are often called mobile virtual network operators (MVNOs). These mobile operators provide remote provisioning and management of M2M connections via over-the-air (OTA) services.

Here, unlike traditional SIMs used in mobile phones, an M2M SIM provided by a specialist operator offers users control over data usage and other features such as activity monitoring and SIM locking. These SIMs can also be provisioned and linked to specific application servers using the tunneling network features.

It’s also important to mention that some M2M specialists also package data plans along with modems and other M2M equipment like gateways, setting up M2M applications as a complete task. These M2M operators are usually carrier agnostic and they build coverage according to M2M application needs.

For instance, while a healthcare monitoring service might suffice with single cellular network coverage, a trucking fleet might require more than one mobile network footprint. Also, M2M users should ensure that their service provider is hands-on with troubleshooting capabilities and can perform troubleshooting remotely and in real-time.

Data plan tiers

Finally, when it comes to the cost of M2M data transfer, and subsequently the economics of data plans, the nature of the application matters a lot. For example, M2M applications such as wireless point-of-sale (PoS) and parking meters use small data packets sporadically; here, pay-per-use data plans make more sense than per device or fixed data plans.

Also, low use monthly plans for 50 kilobytes (Kbytes) to 3 megabytes (Mbytes) per month can suffice for M2M applications such as automated meter reading, asset and vehicle tracking, and security alarm systems. On the other hand, medium use M2M plans, ranging from 5 Mbytes to 150 Mbytes per month, can efficiently serve vending, retail, and healthcare applications (Figure 4).

Diagram of M2M data plans are not a one-size-fits-all packageFigure 4: M2M data plans are not a one-size-fits-all package. (Image source: Data2Go Wireless)

On the higher end, there are high usage plans for digital signage, PLCs for industrial monitoring and control, and smart building management. They span from 300 Mbytes to 4 gigabytes (Gbytes), and are typically used for M2M devices that mandate real-time access to remote locations for transferring large files or content streaming.

There are even M2M data plans for extreme use, ranging from 8 Gbytes to 100 Gbytes, and typically serve devices that require M2M connections 24/7 for streaming high volumes of data. Typically, such M2M applications include backup and redundancy links and video surveillance systems for asset management.

Furthermore, there are M2M data plans that allow users to aggregate data usage across multiple SIMs. So, one M2M device overusing data may be compensated for by another connected device underusing data. Moreover, depending on the application and operator, these data plans provide users with connectivity technologies of their choice: GPRS, 2G, 3G, and LTE 4G data pipes.

Digi-Key Electronics also offers IoT cellular connectivity services through its partnership with several tier-1 wireless operators. These Digi-Key IoT Cellular Data Plans come with universal SIM cards available in mini (2FF), micro (3FF), and nano (4FF) form factors. This provides one-stop shopping for designers using Digi-Key components, M2M and IoT modules, modems, and gateways.

Conclusion

A closer look at the intertwined worlds of M2M and IoT communications shows they are distinct in terms of their network architecture and implementation requirements, but that they also share common building blocks like RF modules, modems, switches, routers, and gateways. Cellular connectivity and its associated data plans offer yet another common ground between these two networking technologies.

Those commonalities, however, make it even more important to understand the dividing lines between M2M and IoT systems because it will matter when calibrating industrial automation design needs regarding security, connection availability and reliability, interface options, and RF robustness.

Disclaimer: The opinions, beliefs, and viewpoints expressed by the various authors and/or forum participants on this website do not necessarily reflect the opinions, beliefs, and viewpoints of Digi-Key Electronics or official policies of Digi-Key Electronics.

About this author

Majeed Ahmad

Majeed Ahmad is an electronics engineer with more than 20 years of experience in B2B technology media. He is former Editor-in-Chief of EE Times Asia, a sister publication of EE Times.

Majeed has authored six books on electronics. He is also a frequent contributor to electronics design publications, including All About Circuits, Electronic Products and Embedded Computing Design.

About this publisher

Digi-Key's North American Editors