Feature: IIOT
network. Within the VPN each router has a fixed and known IP address. Importantly, any device connected to the routers is given a visible and (optionally, fixed) IP address, allowing interactions not only with the routers, but also between devices connected to them. Primary access to the VPN can be via Ethernet, Wi-Fi, fibre or cellular connection, with configurable options to automatically failover between available connections in case of primary communication failure. Each router is loaded with an AT modem emulator application,
which configures a serial port that responds to the AT command set, to create and use point-to-point tunnels between two routers within the network. Tese tunnels then transport any data appearing on a router serial port to the corresponding serial port on the remote router. Tis is analogous to a dial-up system, where a modem responds to the AT command set by creating and deploying point-to-point connections for serial data. If the telephone numbers used within the third-party devices
can be changed easily, then all a user needs to do is change the phone numbers to the IP address of the desired destination router. If this is not easy, then scripting within each router can be used to convert the existing phone numbers provided by the third-party device to the corresponding IP address used within the network. Te call connect/disconnect follows normal AT command
principles, making the IP network completely transparent to the third-party devices, which continue to operate as if still connected via a 2G or dial-up network. Importantly, the system is designed to be used in a point-to-multipoint configuration typically found in SCADA networks.
Modem emulator Te Advantech modem emulator has the following characteristics: • Command ATD will create a tunnel to the corresponding remote router.
• If the remote router is running a session (with another router) then the call will not be answered (i.e., a router will only support one active dial-up session at a time). Tis is the equivalent of the situation on a PSTN network where a call can’t be completed to a number that is already in use (engaged).
• Once a call is established, whatever is received at the serial port on one router will be output from the serial port on the other router. Te system is agnostic to the context of this data, so legacy protocol information between the SCADA endpoints is simply passed transparently.
• If redundancy is required, then this works in the same way as for PSTN – i.e., there is a one-to-one correlation between an existing PSTN modem and the router to replace it. In set-ups where the central system has a pool of available modems for reduced congestion, equivalence is achieved by simply replacing each host modem with a corresponding router.
Additional implementation advantages Once implemented there are several other functionalities that can be used to further enhance the system, although in some cases with some added costs. For example:
40 March 2024
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Remote router management WebAccess/DMP brings with it zero-touch installation and remote management of the router estate, which reduces the total cost of ownership and allows future modifications and additional edge applications. In addition, WebAccess/DMP offers a full set of API calls, allowing its functionality to be accessed from any authorised and connected application.
Remote third-party device management If the third-party devices have a separate local configuration/ diagnostics port, then this can be connected via the VPN to provide remote connectivity to the management system – for example, from a standalone application running on a PC connected to the VPN. If the configuration/diagnostics service is provided via Ethernet, then this can be directly visible through the router. If provided via a serial connection, then a second serial port on the router or external network attached serial interface can set up a terminal server connection via the VPN, allowing remote interaction.
Additional edge device connection Whilst the described system aims at the migration of legacy 2G and dial-up data acquisition communications, once the routers and VPN are in place, they can provide inter-site connectivity for other devices, using the always-on nature of the IP network and the grouping/isolation features available via WebAccess/ VPN. Tese allow router and connected device visibilities to be restricted based on the user profile; for example, access to the router configuration can be restricted to the IT department, whilst access to connected remote devices such as SCADA RTUs, PLCs, flow computers and others can be limited only to select personnel, with added granularity to site-, group- or device-level. Note that this function is independent of the dial-up emulation.
WebAccess/VPN working in combination with the routers provides not only fixed and visible IP addresses for each router, but can be configured to provide visible (and, optionally, fixed) IP addressing of any device connected to the routers, allowing systems to interact directly with all IP-based devices at a remote site.
Using the router as edge device Te router allows other applications to be installed, which can come from an existing range of user applications, be developed as C code or Docker applications by the user, Advantech or third parties, or use Python Scripting or NodeRED application framework downloads. Advantech and its partners offer several pre-existing edge applications, including: • interface to legacy utility equipment using native protocols such as IEC 60870-5-101/103/104, DNP3.0 and Modbus; • an IEC-61131 ‘soſt’ PLC programming environment; • interface to IT enterprise systems, e.g., via MQTT for AI/ML inference. Advantech also offers many other IoT intelligent systems and embedded platforms.
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