Sending Plant Data to the Cloud: Protocol, Edge and Cellular Gateways Compared

Energy meters, PLCs and drives speak Modbus or fieldbus protocols; cloud platforms speak MQTT or HTTPS. The gateway in between decides how reliable, secure and maintainable the data path will be. We group the options into three kinds and look at one well-known example of each, using public documentation only.

Illustration: factory with smart meter, data logger and energy dashboard

Tap or click the diagram to enlarge it.

Three Kinds

Pick by Job

They overlap, but each is strongest at one job.

Protocol gateway with MQTT — Moxa MGate 5105-MB-EIP

Translates Modbus and EtherNet/IP and can publish to the cloud, with no programming.

Generic MQTT v3.1.1 plus built-in Azure IoT Hub and Alibaba IoT Platform modes; TLS with your own certificates.
Up to 300 data tags; microSD buffering up to 2 GB when the cloud connection is lost.
Best when you need a fixed-function, configurable box for a modest number of Modbus points.

Edge gateway — Siemens SIMATIC IOT2050

Siemens describes it as a retrofit IoT gateway that collects, processes and stores machine data on site, then forwards it to local or cloud systems.

Per Siemens' page: 2 GB DDR4, Gigabit LAN, an mPCIe port for wireless cards, two USB ports, one serial port and one Arduino port.
A platform for local processing, so expect software work: the page does not list protocols or operating system, so check Siemens' operating instructions.
Best when data must be filtered, calculated or combined before it leaves the plant.

Cellular router with serial — Teltonika RUT956

An industrial 4G router with RS232/RS485 ports, for sites with no wired Internet.

4G LTE (Cat 4) with 3G/2G fallback, dual SIM with automatic failover, GNSS, Wi-Fi and wired connectivity.
RutOS software with remote management through Teltonika's RMS; its wiki documents Modbus gateway functions, including MQTT. Check current firmware docs.
Best for remote or temporary sites. Confirm LTE bands and regional variants for your carrier in Thailand before ordering.

Design

Cloud Connection Checklist

Whichever gateway you choose, these points decide whether the data path is dependable.

1
Outbound connections onlyLet the gateway connect out to the cloud over TLS (for example MQTT on port 8883). Avoid opening inbound ports on the plant network.
2
Plan for outagesCheck whether the gateway buffers data when the link drops, and for how long. Some units use a microSD card for this.
3
Time stamps and tag namesAgree on units, tag names and time zone up front so dashboards stay consistent across sites.
4
Certificates and passwordsChange defaults, use your own certificates where supported, and record who holds the credentials.
5
Who owns the cloud account?Decide early who pays for, owns and can read the data, especially if an integrator sets it up.

Relation to energy monitoring The data logger in an energy management system does this same job: it polls the meters and forwards readings. See our meter, logger and software guide.

This is a desk-based comparison using the manufacturers' public documentation, read in October 2026. We did not bench-test these units for this article. Specifications, firmware and model status change, and even a manufacturer's own pages can disagree — always confirm in the current datasheet before you specify or buy. Brand and product names belong to their owners; mention here is not an endorsement.

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Sending Plant Data to the Cloud: Protocol, Edge and Cellular Gateways