WM-EIS ISKRA® Metering Modem

Document Specifications

This documentation presents the installation and configuration steps for the WM-EIS ISKRA® energy metering modem.

Chapter 1. Introduction

The WM-EIS ISKRA® modem is suitable for remote reading of electricity meters on LTE-based cellular networks. It offers cost savings by eliminating the need for manual meter system readouts.

Wireless Communication

The modem is available with different cellular module types:

• LTE Cat.4 / 3G / 2G module
• LTE Cat.1 module with 2G "fallback"
• LTE Cat.M / Cat.NB module with 2G "fallback"

In case of LTE 4G network outage or inaccessibility, devices with a 2G mode or "fallback" feature will continue communication on the 2G network.

The modem can be configured to use specific networks (e.g., only LTE 4G or 3G) or the best available network (Auto mode). It also supports GSM-CSData connection, initiated via CSData calls for compatible modules.

The modem supports multi-operator SIM cards and roaming, providing a SIM-card and mobile operator independent solution.

Design and Installation

This modem is specifically developed for Iskra® MT830 and MT831 3-phase electricity meters.

It features different data connectors for RS232 and RS485 interfaces, allowing connection to the meter. The device can be installed under the meter's sealed terminal cover without compromising the seal, offering future expansion possibilities, especially in space-constrained installations.

Each modem model can be ordered with a housing tailored for specific meter types. It can also function as an external modem for universal meters, with an optional 35mm DIN-rail adapter for mounting.

Operation Properties, Features

The modem is designed for retrieving current and stored measurement data, reading event logs and load curves, and remotely managing meter parameters.

It operates in a "Pull" mode, enabling transparent data transmission from the meter to the HES (smart metering center/server). Remote access is available via the mobile network, capable of sending data over the Internet using an APN.

The modem facilitates transparent data transmission between the metering server or service provider via CSData call (for 2G) or mobile internet (TCP) connection, supporting meter registers, remote reading, parameter modification, and firmware updates.

Connections

The device can be ordered with the following connection outfits:

• RS232 (DSUB-9 connector / 2-wire connector interface) for modem configuration and meter connection
• RS485 (2 or 4-wire connector) for meter connection

Power Source and Power Outage

The device is powered from the meter's mains connection (100V-240V AC).

Connection modes:

• a) For meters on 57.7/100V AC power network: connect to line voltage (100V, L1..L2, L2..L3, or L1..L3).
• b) For meters on 230/400V AC power network: connect to phase voltage (230V, L1..N, L2..N, or L3..N).

Supercapacitor

An optional supercapacitor component provides power outage protection, allowing the modem to continue operation during minor power interruptions. During an outage, the supercapacitors discharge, and the modem shuts down. Upon power restoration, it restarts and sends data, with the capacitors recharging.

Configuration and Firmware Refresh

The modem can be configured locally via RS232 or optical port, or remotely via CSData call (requires 2G network setting) or mobile internet (TCP) connection. Firmware can also be updated.

Configuration is possible via TCP port remotely or local serial connection. It requires setting the APN, username, and password, information provided by the local mobile operator.

Software and Security

All settings can be configured using the WM-E Term® administration tool or via API for integration into existing administration environments. Configuration can be done for individual devices or groups.

The WM-E Term® tool is password-protected and supports user management. It requires a Windows® platform and is available in English and several other languages.

The WM-E Term® tool also facilitates safe firmware changes for devices, either locally or remotely.

Security features include hardware identification during firmware replacement and operation, protection against third-party or modified firmware, and integrity/compatibility checking. The device's flash content is encrypted with a unique AES key. It uses a special communication protocol with double checksums for data safety. The control port is AES encrypted (optional).

The modem can be configured with unique configuration and optional communication passwords for enhanced security. TLS protocol protected firmware is available for maximum security.

Status and Notification

The modem continuously monitors the mobile network and communication health, sending status information like signal strength and QoS. It can also send SMS alarm notifications and Last Gasp notifications, depending on the cellular network and mobile operator capabilities.

Certificate

The modem complies with CE certification, the Radio Equipment Directive (ReD) standard 2014/53/EU (parts 3.a, 3.b, 3.c), and ReD Cybersecurity part 3.d. It is RoHS and CE certified.

Chapter 2. Connectors, Interfaces

2.1 Internal View

The internal view of the modem shows the following components:

• 1: Mains connector (pigtail connector, for AC power)
• 2a: RS232 connector (DSUB9 or 2-wire option)
• 2b: RS485 connector (2-pin or 4-pin option)
• 3: Antenna connector (SMA-M, 50 Ohm)
• 4: SIM card slot (push-insert)
• 5: Plastic holder (for lower plastic case fixation)
• 6: Plastic hooks (for mounting into electricity meter terminal cover)
• 7: Status LEDs
• 8: Fixation screw of top modem enclosure
• 10: U.FL antenna connector
• 11: Supercapacitors (order option)

2.2 Installation Steps

1. Remove the meter terminal cover and loosen the screws.
2. Ensure the device is powered off, then remove the AC connector (1) from the meter.
3. Insert a replaceable and active SIM card (with APN) into the SIM-holder (4). The chip should face down, with the cut edge towards the modem. Push until it clicks. The SIM card can be removed by pressing it again.
4. Install the modem enclosure (5) near the meter or mount it securely on a wall. It can be inserted into the meter's internal mounting points under the terminal cover (18) as per the meter's user guide.
5. Mount an external antenna to the antenna connector (3) for the desired communication type (e.g., LTE).
6. Connect the modem to your computer using the RS232 cable (2a) and an RS232/USB dongle converter.
7. Connect the modem's AC power connector (1) to the meter's power input (100-230V AC) or an external 230V power supply.
8. Configure the modem using the WM-E Term® software.
9. After configuration, remove the RS232 cable (2a) from the USB adapter.
10. Disconnect the modem's AC power connector (1). The modem will shut down.
11. Establish a data connection between the modem and the meter using the desired interface (e.g., port "2a" to the meter's RS232 connector "G").
12. If using RS485, connect the modem to the meter via the RS485 connector (2b) using the data cable.
13. Reconnect the modem's AC power connector (1) to the meter's power input. The modem will power up, and LEDs will indicate activity.
14. Replace the meter's terminal cover and secure it with the screws.

2.3 Connecting the Modem to the Meter (Iskra® MT830, MT831 Meters)

1. Remove the Iskra® MT830 or MT831 meter's communication module plastic case by releasing the two screws from the top.
2. Connect to the meter using the data connector. Connect the RS485 (2b) signed cable (2-pin wire/sleeve, brown and white wires) to the meter's RS485 input. If the input has 4 pins, connect all four cables to the place marked with "D". The modem can also be ordered with a "pigtail" connection.
3. Connect the modem's plastic power plug (1) to the meter's two-wire connection (marked "E"). If the AC power connector is a wire end ferrule, connect the wires to the meter's phase and ground.
4. Connect the appropriate antenna (3) to the modem's swing connector.
5. Connect the wire end sockets of the modem AC cable (1) to the meter's AC power connection points (red and black wires). Attention! The meter may be under 100-240V AC supply voltage during this step. The modem receives its power from the meter. NEVER remove the device cover when the modem is powered on!
6. Attach the modem (signed "G") under the terminal cover of the meter to the designated part (tabs marked "H") or another attachment point.
7. Replace the terminal cover on the meter, slide it on, and secure it with the two screws.

2.4 Antenna Connection

Sufficient signal strength is required for proper modem operation. An internal antenna may suffice if the cellular network signal is strong. For areas with weak signals, an external 50 Ohm SMA connector antenna is recommended, which can be mounted on the modem or placed inside the meter's top cover.

2.5 Operation LEDs

The LEDs are numbered from left to right on the modem panel: LED1 (blue, left), LED3 (green, center), LED2 (red, right).

Factory Default LED Signals:

Factory default LED signals can be configured via the WM-E Term® tool.

Configurable LED Functions

The following functions can be assigned to LEDs (LED1-LED3) in WM-E Term®:

• Not used
• GSM / GPRS status
• SIM status
• E-meter status
• E-meter relay status (for WM-E3S CIR version)
• M-Bus status
• Firmware status
• Network status and access technology
• Meter status with IEC polling
• AMM (IEC) client state

Further Status LED Signals (Configurable)

* The e-meter's power supply can be controlled by the relay. Cannot be used for tariff change.

** The EI client is a transparent TCP channel from the modem to the EI server.

Relay status: "Disconnected" (active mode, LED on). "Connected" (normal mode, LED off). "Ready for Connection" (LED flashes once per second).

During firmware upload, LEDs indicate normal operation. After installation, LEDs light up for 5 seconds, then the modem restarts with the new firmware.

2.6 Internal Connectors

The modem features internal connectors:

• RS232: 4-pin internal connector (CN500), with serial cable outfit to DSUB-9 connector (or 2-wire option).
• RS485: 4-pin internal connector (CN501), with cable outfit leading to 2- or 4-wire connector.
• Order option: 2 INPUTS (4-pin connector CN502) with cable outfit for 4-wire connection to external devices. Pinout: black wire (#1), white wire (#2).

2.7 RS232 Connector Pinout (Internal CS5 Connector)

On the CS5 connector, pin nr. "1" (marked by red circle) is the GND connector.

2.8 RS485 Connector Pinout (Internal CS7 Connector)

On the CS7 connector, pin nr. "1" (marked by red circle) is the RX+ connector.

2.9 Power Outage Management

The modem supports the LastGASP feature if supercapacitors are present. This allows the modem to operate for a short time during a power outage. Upon detecting power loss, the modem generates a "POWER LOST" SMS. Upon power recovery, it generates a "POWER RETURN" SMS. LastGASP message settings are configurable via the WM-E Term® application.

2.10 Push Operation Method

The modem does not operate continuously. It supports data sending modes for remote readout at predefined intervals or triggered by events (e.g., meter cover removal, incoming SMS). The modem connects to the mobile data network only during data transmission.

It requires a GSM network connection and readiness for GPRS, but without an active IP connection.

Data Push (starting at predefined times):

• Triggers FTP file upload (plain text or encrypted).
• Generates unique filenames automatically.
• Requires an FTP server accessible from the mobile network.
• FTP must be set to passive mode.
• Files consist of register read and event log (last 31 days).
• Readings are in standard IEC format, including ASCII control characters.

Alarm Push (sending alarms):

• Triggers when a new event is read from the meter.
• Sends TCP data containing IP address, listening port, and meter ID.

Triggering with SMS:

• GPRS connection can be activated remotely via SMS (empty text).
• After receiving the SMS, the modem connects to the IP network and acts as an IP server for a defined period.

2.11 LED Operation During CSD Call

A CSD call can be used for two purposes:

• a) Reading/configuring a meter in transparent mode.
• b) Performing modem configuration/firmware update.

For transparent meter reading/configuration:

• GSM/GPRS status LED remains continuously lit.
• E-meter status LED flashes every half second, or remains continuously lit if the measuring interface is not configured for 9600 baud.
• LEDs turn off after the connection closes.

For modem configuration/firmware update:

• GSM/GPRS status LED remains continuously lit.
• Other LEDs do not change due to CSD mode.

2.12 Configuring from CSD Connection

If the modem restarts due to incorrect configuration, it can be accessed via a CSD call. Fine-tuning is possible in WM-E Term® software via the PDP connection delay field in the APN parameter group.

2.13 Automatic Network Reconnection

If the mobile network provider drops the modem due to inactivity, configured parameters can trigger automatic connection rebuild. If the provider sends a "data connection lost" message, the connection is restored automatically. Alternatively, two workarounds can be used:

• a) Active Mode (Periodical Ping): Configure Watchdog parameters like Ping IP-address, Number of ping retries, Ping wait-time, and Wait-time. If no ping response, it reconnects after the interval specified in "Seconds, GPRS connection closed and restored after this time". Attention! Frequent pinging increases data traffic but improves network connection stability.
• b) Passive Mode (Connection Retry): Use the "Seconds, gprs connection closed and restored after this time" parameter. This defines how long the modem waits before attempting to reconnect after a network drop. Consult your mobile provider for recommended settings. Attention! Low data traffic and no ping configuration may lead to short network stays. Setting this parameter too low can cause frequent reconnections; do not set it lower than your provider recommends.

2.14 Two Meter Readout Ports

Every WM-E modem has two ports for meter communication, configuration, and firmware updates, with configurable priority.

• Primary Port (Utility Communication Port): Used for meter readout and configuration. It has higher priority and overrides the secondary port's operation.
• Secondary Port (Customer Communication Port): Used with lower priority for meter communication, configuration, and firmware updates.

The two ports should be set to different port numbers.

This feature is available in modem firmware v5.3.4.1 or newer.

2.15 Automatic Protocol Detect and Switch

The "Data format for meters" value (E-Meter serial port) can be configured in WM-E Term® (Standard settings or Advanced settings Transp./NTA parameter group).

The 'Auto' mode setting allows the modem to check the first data packet of an incoming connection. It decodes communications and switches to data mode 7E1 for the meter if it detects the IEC protocol; otherwise, it remains in 8N1 mode.

For WM-E1S modems, the firmware also changes the data mode for both RS232 and RS485 ports, as the meter's connection port is not always known. The modem detects the protocol-corresponding format and sends only necessary communication.

This feature is available in modem firmware v5.3.4.1 or newer.

Chapter 3. Modem Configuration

3.1 Configuration

The modem must be configured using the WM-E Term® software before normal operation. Configuration involves setting meter, modem, and communication parameters, and allows testing modem communication.

The modem can only be configured through the RS232 connection!

During configuration, disconnect the meter-modem data connection (2a) and connect the modem to your computer.

Until configuration, the modem is not connected to the meter and cannot read parameters via RS232. Use an Optical or TCP/IP port for this purpose.

The modem connects via its RS232 cable (2a) using a USB dongle adapter to your computer.

During configuration, the modem must be powered by an external source (100-230V AC) or the meter (57-100V AC).

Refer to the WM-E Term User Manual for detailed configuration instructions.

Proper modem communication requires configuring SIM settings: PIN code, APN, username, and password, all manageable via WM-E Term® through the serial link. Adequate signal strength is essential for successful operation.

Signal Strength

Use an internal antenna in areas with strong signal strength. For areas with poor reception, mount an external 50 Ohm SMA connector antenna to the device's antenna connector (3), which can be placed inside the meter enclosure.

To read meter parameters during PC-modem connection after RS232 configuration, select a different configuration port (e.g., TCP/IP or Optical) to the meter.

3.2 Configuring the Modem by WM-E Term®

The Microsoft .NET framework runtime environment is required.

Download WM-E Term® software from: https://m2mserver.com/m2m-downloads/WM-ETerm_v1_4.zip. Unzip and execute WM-ETerm.exe.

The configuration software supports user account management and password changes. Log in with a password and consult the WM-E Term® User's Guide.

Device LEDs indicate the modem's current status.

A factory configuration file sample is available at: https://m2mserver.com/m2m-downloads/WM-E1S_STD_v5210_default.zip.

For modem operation, cellular network communication and SIM card settings (APN, password, account) are necessary. Review and save transparent mode data speed functions for RS232/RS485 settings in WM-E Term®. Then, send the configured settings to the modem.

The WM-E Term User Manual is available at: https://m2mserver.com/m2m-downloads/WM-E-TERM_User_Manual_V1_97.pdf.

3.3 Sending an SMS from the Meter

Depending on meter configuration, the modem can send SMS messages using standard AT commands to a configured phone number. This is useful for alarms and special events.

3.4 Signal Strength

Check cellular network signal strength in the WM-E Term® software's Device Information menu or by using the [Signal Icon]. The current status information will be updated upon completion.

Check the RSSI value; it should be yellow (average signal strength) or green (better). Adjust the antenna position if necessary, but note that dBm values may not improve without re-reading the status.

Chapter 4. Support

For technical questions, contact WM Systems:

• Email: support@m2mserver.com
• Phone: +36 20 333-1111

4.1 Support

The product has an identification void containing important product information for the support line. Warning! Damaging or removing the void sticker voids the product guarantee.

Online product support is available at: https://www.m2mserver.com/en/support/.

4.2 Product Support

Documents and information related to the product are available at: https://www.m2mserver.com/en/product/wm-els-iskra/.

Chapter 5. Legal Notice

©2025 WM Systems LLC. This document and its illustrations are protected by copyright. Copying, usage, replication, or publication of the original document or its parts requires explicit agreement from WM Systems LLC.

The figures in this document are for illustration purposes and may differ from the actual appearance.

WM Systems LLC. assumes no responsibility for text inaccuracies in this document. Information is subject to change without notice. Printed information is for informational purposes only; contact WM Systems for further details.

Warning! Any fault or error during software upload/refresh can lead to device breakdown. Contact WM Systems specialists in such cases.