Long-life battery powered, cellular IoT data logger for meters with Pulse, RS232, RS485 and Serial Encoder interfaces
Robust, ultra low-power cellular IoT data logger, which comes with a built-in LTE Cat.M, NB-IoT cellular module ensuring reliable data transfer in any environment.
The device can be connected to any meters or sensors with pulse, RS232, RS485 output or Serial Encoder interfaces.
Easily upgrade existing meters and sensors with cellular connectivity, safeguarding your investments without the need for costly replacements!
Offering a standalone operation, it performs reliable automated meter readings. The device allows connections of max. 2 pulse, 31 Modbus, and RS232 meters and further meters
through its serial encoder input.
The WM-i SERIAL data logger counts and collects all data of connected devices, then it transfers data at predetermined intervals to the Microsoft® Azure or other Cloud IoT platform with MQTT protocol encryption via LTE Cat.M / NB-IoT network.
| Device type | IoT data logger for meters, sensors |
|---|---|
| Primary use case | Smart water and gas metering (AMI/AMR), LTE and Cat.M upgrade of legacy meters |
| Cellular & RF Access Technology | LTE Cat.M/NB / 450 MHz; 2G fallback |
| Protocols | IEC, TCP, Modbus, Serial Meter Encoder, MQTT (with Azure compatible mode) |
| Interfaces, Physical Connectors | Pulse, RS232, RS485, Serial Encoder, USB-C |
| Server | IoT Cloud, Azure Cloud |
| Meter compatibility | Pulse output meters, Modbus meters and sensors, Meters with encoder output |
| Power & Environment | internal DC battery with 19,000mAh capacity / optional external battery pack — between -25 Celsius and +70 Celsius degree |
| Approvals & Certifications | CE, RoHS, ReD DA, IP 68 Protection |
| Firmware | ThreadX (RToS embedded system) |
| Configuration / Remote Management | WM-E Term configuration software (downloadable) via local or TCP / Azure IoT Cloud |
| Security | TLS, SHA-256, Tamper protection |
The easily installable device was designed for long-term, maintenance-free operation, the WM-i SERIAL boasts a high-capacity battery lasting up to 10 years and an IP68 waterproof casing, making it ideal for challenging environments.
Optionally, add-on extension possibilities are available to extend capabilities for PoCs, unique orders (e.g. different connections, adding sensors).
The WM-i SERIAL data logger is delivered with one high-capacity 19,000 mAh battery included. This provides long-lasting, reliable operation even in demanding applications.
For extended autonomy, the logger can be ordered with an optional external battery pack. This pack contains three additional 19,000 mAh batteries, giving you a total of four batteries (1 internal + 3 external).
If you decide to add the external battery pack later, we recommend also replacing the internal battery with a new one. This ensures all four batteries are at the same charge level, which is important for optimal performance and long-term reliability.
Datasheet
Updated: 2025-11-17
WM-E Term configuration software (WM-i compatible)
Updated: 2025-12-04
Video tutorial – Chapter 1. How to configure the WM-i data logger in Azure with the WM-E Term software
Extra Battery Pack for WM-i Data Loggers: Extend the lifetime of your IoT smart metering device
4G LTE antenna with magnetic mount, SMA connection, 2.5m long RG174 cable, 6dBi max. gain
