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Remote PLC access

June 20, 2019 by Oliver Rieder

Remote PLC access with Serial to Ethernet Connector software

What is a PLC?

A PLC or programmable logic controller is a type of computer often employed to monitor and control industrial manufacturing operations. The device, which you may see referred to as a programmable controller, can be vital in identifying errors in industrial processes. PLCs are designed to be durable with the ability to withstand the physical challenges of an industrial environment. They are easy to program and are used to control robotic equipment, assembly line manufacturing, and other industrial activity that demands reliability.


PLCs are part of the basic infrastructure of industrial automation implementations. They can be used as a stand-alone computer to control an individual industrial machine or process. In many cases, multiple PLCs are connected in a network and used as a component of a SCADA system. The networked PLCs are controlled by servers running specialized HMI and SCADA software.

Human interaction with the network-connected PLCS is enabled by the use of a Human-Machine Interface (HMI). Configuration, monitoring, and controlling the PLCS is all done through the HMI. Generating alarms for human operators based on PLC input is another critical use of PLCs. HMIs can be simple or complex. A very basic HMI may consist of light and buttons that afford the operator the ability to perform designated functions. More complex HMIs involve a computer executing programming and monitoring software interacting with a network of PLCs.

Industrial automation systems generally follow a similar control structure. They are comprised of human operator interfaces that rely on PLCs to monitor and control industrial devices. Physical properties such as temperature, humidity, and pressure are monitored by the sensors. The electrical signals generated by these sensors is used by logical controllers to initiate various activities such as starting a device or process. Operators with access to an HMI can monitor the automated processes. In some circumstances, the operator may have the ability to override the automation to deal with a procedural anomaly. The synthesis of sensors, actuators, and logic controllers with an HMI forms the basic architecture of all automated control systems.

Accessing a PLC remotely

There are communication interfaces present in the majority of PLCs. These ports commonly employ the RS-232, RS-422, RS-485, or Ethernet protocols. PLC configuration is enacted through these communication ports. Connecting the PLC to a network is accomplished with the Ethernet port, which is a standard feature of most devices. The servers being used to control and monitor the process through the PLC gain access to it through the network connection. Other network-connected devices can also communicate with the PLC.

Virtual connections are required in order to achieve remote access to the PLCs.

Software for Network access to PLCs

PLC control software has no utility unless it can be used over a network. Serial to Ethernet Connector is a specialized application designed for remote access to RS232/485/422 interfaces. The software enables the sharing of any serial interface over a network. Any type of network including LAN, WAN, and IP is supported by this versatile communication tool.

In order to access PLCs remotely, follow these simple steps:

  1. Download Serial to Ethernet Connector.
  2. Install the application on a network-attached physical or virtual machine with which you want to access serial ports.
  3. Select “Create Server Connection” in the main window.
  4. Configure the connection settings to address your situation.
  5. Establish a client connection on the remote computer.

It’s really that simple to manage network-attached PLCs remotely. Serial Port Monitor is an excellent tool for developing, implementing, and maintaining networks of PLCs and their applications.

Eltima Software uses the technology behind Serial Port Monitor to develop custom solutions for their clients. See what we can do for you by requesting a sample of PLC HMI virtualization technology that can be incorporated into your system or application.


Oliver Rieder

I'm Oliver Rieder, a freelance Technical Author and USB & COM technology expert. I've been in the industry for over 9 years now and have worked with some of the biggest names in tech.

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