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Remote access to a Unitronics PLC & HMI

Remote access is fast becoming a favourite among both clients and suppliers because ongoing maintenance costs are kept to a minimum and response times shorten considerably.  As more clients call for the logging of process parameters the site database can be uploaded by remote access as often as required, giving up to the minute performance and monitoring.

With this in mind Unitronics have designed their range of integrated PLC & HMI products to be easily accessible remotely, whether this be via modem or the Internet.  Some of the key aspects of remote access to consider are health & safety, security and connection quality. The health & safety aspect is for the individual companies concerned to consider for each site, what is safe to do remotely is of paramount importance.  Other aspects depend on the functionality of the equipment used and the method of connection with Unitronics products being particularly suited for safe secure monitoring.

Connection methods

There are several ways of remotely connecting to a Unitronics PLC/HMI either by landline, via broadband or over the GSM/GPRS network.  It goes without saying that remote access requires a solid connection method, for example, a GSM/GPRS connection does rely on having a strong consistent signal so a remote moorland site may not be accessible.  i4 Automation can advise on the merits of different connection methods through their partnership with Westermo who manufacture a wide range of industrial communication products.


In the modern world it is sadly necessary to protect your systems and data against cyber attacks which requires careful implementation at all levels.  Westermo communications equipment can have inbuilt firewalls and can generate VPN tunnels to minimise security breaches while Unitronics products have several levels of security passwords to prevent unauthorised access to different areas.

Remote access functions

There are different functions that be be performed remotely, once a solid connection has been established it is possible to program, monitor, or control the application and to upload or download data.

Remote programming

Visilogic programming software

The free of charge Unitronics programming software can connect to a remote site and program or monitor a remote PLC, indeed if the remote site contains several networked PLC's then Visilogics can target all of the PLC's individually.

Remote Operator Application

Visilogic Remote Operator App

Using the free Remote Operator app for iOS and Android mobile devices you can monitor automation processes, press keys, touch HMI objects, change parameters, view Alarms, process value Trends and much more. All without needing to be in the same building as your PLC. You can define and access multiple controllers from a single mobile device.

Remote operation

Visilogic programming software

Using a free of charge Unitronics utility program called Remote Operator it is possible to remotely view the HMI screens and control the application by using the PC mouse to virtually 'push' the buttons on the HMI.

SD card access

Visilogic programming software

Unitronics Vision PLC's all have an SD card that can be fitted to provide large amounts of storage space for recipes, web pages, trends or process parameters.  Using the free of charge SD Card Suite it is possible to manage the files on the SD card and transfer files remotely.

Web Server

Each Unitronics Vision PLC is capable of acting as a Web Server and publishing pages to the Internet which can act as a useful method of allowing users limited access to application parameters.  The web pages can contain Java script and use Ajax extensions for additional functionality.

i4 Automation can provide technical assistance in designing your remote access system, we have a thorough understanding of the Unitronics products and access to world class Westermo communication technology.  Remote access can be safe, secure and easy.