Modems add intelligent comms to PLCs

A Mitsubishi Electric Automation Systems product story

Edited by the Engineeringtalk editorial team Mar 31, 2006

Mitsubishi Electric has introduced a line of intelligent industrial modems for its Melsec FX compact PLCs and Alpha XL microcontrollers.

Mitsubishi Electric has introduced a line of intelligent industrial modems for its Melsec FX compact PLCs and Alpha XL microcontrollers.

Called the Mitsubishi Alarm Modems (MAM) these have a nonvolatile memory and internal processors for handling the entire datacommunications process and are configured via easy to use alarm editor software called MX Alarm Modem Editor.

This places no additional load on the controllers, which could otherwise impact the data communications process, memory capacity and cycle times.

The modems provide access to remote machines, automated systems and plants, enabling inexpensive implementation of remote maintenance, diagnostics, monitoring, alarms and tele-service applications.

They operate over international analogue telephone networks or the European-standard GSM digital mobile networks in the 900 and 1800MHz bands.

Standard modems are also available for simple telemetry applications.

Mitsubishi modems are autonomous communications controllers with their own 32bit microprocessors and up to 66Mbyte of Flash memory.

They can send data by SMS text messaging, email or fax and can receive by SMS.

They are preconfigured with controller protocols so do not require a driver to be loaded in the controller nor changes to the controller program.

They are DIN rail mounting and connect to their associated controller with a standard serial cable.

Alarm messages, telephone numbers, email addresses and other data are entered with MX Alarm Editor, a user-friendly software package.

Up to 100 addresses, message texts, controller values and alarms can be stored in the modem.

With a few mouse clicks the user can link message texts (the length of which is not limited) to controller values (current operating data, inputs and outputs) and target addresses to alarms.

A multi-level alarm plan referred to, as the "alarm cascade" makes sure that important messages reach the addressee promptly.

If a message is not confirmed within a preset period the modem then automatically sends messages to other addresses, if necessary using different communications channels.

This ensures that service staff responds quickly to malfunction information and maintenance requests.

The modem also provides access to the entire controller program for remote maintenance functions.

Users in any location can quickly obtain an overview of the current production, machine or plant status.

Caller number identification prevents unauthorised dial-ins and additional security is provided by support for connections with a user name and password system.

The modem can also be configured to send a confirmation to the user when a command has been executed.

Modems with remote maintenance and tele-service functions are particularly useful for distributed applications with small devices and stations that are not connected via a control network.

Using modems, controllers in remote locations and mobile systems can be inexpensively integrated into modern service concepts.

Typical applications include: building services; cooling, heating and air conditioning systems; tank storage facilities; pump and water stations; container transporters and other specialised vehicles.