A Programmable logic controller (PLC) system is an industrial computer that monitors information from input devices and makes decisions affecting the control of output devices. These systems offer the potential to automate processes, machine functions, and entire production lines.

The design of PLC systems includes a range of robust features that allow them to be installed in various environments, including harsh industrial ones. Despite these machines being inherently tough, there are some factors to consider to ensure proper operation and enhance their lifespan.

 

Careful installation, troubleshooting and maintenance can make a huge difference to the functionality of a PLC system and reduce the potential of problems that could lead to downtime or the replacement of parts.

In this guide to PLC control system installation, troubleshooting and maintenance you’ll find out everything you need to know to guarantee the functionality and longevity of your PLC system.

 

Installing a PLC system

When installing a PLC system, it’s important to take the proper steps and care to reduce potential risk factors and damages. The exact installation procedure and how to install PLC software will depend on the manufacturer of the unit. It’s important to read the manual thoroughly to avoid any missed instructions or mistakes.

First of all, here are some things to keep in mind for proper PLC installation:

• Avoid installation in places where the PLC would be exposed to direct sunlight
• Ensure the temperature of the installation location doesn’t exceed 55°C and it is not too humid
• Do not install the PLC system where there is a lot of vibration
• Ensure it is installed at an appropriate distance from other high voltage equipment or power lines to avoid electromagnetic interference
• Install the machine somewhere there isn’t oil or dust present 
• Allow space for air circulation

 

 

Installing the CPU unit and Input/Output (I/O) modules

When installing the CPU (central processing unit), keep in mind that it should have adequate airflow and be placed in the correct position on a horizontal surface.

The cabinet it’s installed in should be ventilated to prevent overheating of the unit. At this stage, it’s simply a matter of ensuring each I/O module is installed and connected in the proper location.

Each module terminal is then wired to any field devices that have been assigned to its specific terminal address

The user must remember to remove the power source before beginning the installation and wiring of any module or unit for safety reasons.

 

Wiring considerations

• Wire size: The user must ensure that the wire is the correct gauge and size to withstand the maximum current.
• Labelling: Be sure to label wires and terminals using a reliable method to simplify maintenance and troubleshooting.
• Wire bundling: This technique is carried out to simplify connections to the various I/O modules. Wires that connect to a single module are bundled together and tied, then routed through a duct with other wires with the same signal characteristics.

 

Considerations for special I/O connections

Some wiring connections for field devices require extra precautions, such as leaky inputs, output fusing, and shielded cables.

• Leaky inputs: These refer to field devices with a small leakage current even in “off” mode, including triac and transistor outputs. Placing a bleeding resistor across the input introduces resistance to the circuit and causes the voltage to drop. The leakage current is then routed through the resistor, minimising the current to the input or output module. 
• Fusing outputs: In the case where an output does not have internal fuses, it is required to install fuses externally during the first installation process. 
• Shielded cable: These should be used for control lines in order to protect low-level electrostatic and magnetic signals from coupling with other lines carrying changing currents.

PLC installation can be complicated. The experts at Preferred Spares can provide advice and insight to help ensure your PLC system installation process runs smoothly.

 

PLC troubleshooting methods

There are many different ways to troubleshoot problems with your PLC system. In harsh industrial environments, it’s inevitable that problems will come up that require quick solutions.

Troubleshooting is required when working with PLC systems, but you’ll be glad to know that many problems can be efficiently diagnosed and dealt with if you take the right approach. Here are some tips for effectively troubleshooting PLCs.

 

Keep replacement parts at hand

One best practice when it comes to troubleshooting for PLC systems is to keep a stock of replacement parts where the system is located. This will help you to reduce overall downtime that occurs due to component failure. If a shutdown does occur, it will only last minutes as opposed to the hours or days it might take for spare parts to arrive.

As one of the leading electrical equipment suppliers in the UAE, Preferred spares stocks a range of industrial automation parts from top manufacturers and offers expedient delivery throughout the region to ensure customers always have the parts they need.

 

I/O system module failure

A common issue that arises with PLC systems is I/O system module failure. Troubleshoot this problem by identifying the disconnect between the internal and external situations. This involves examining the relationship between the physical I/O modules and what’s happening inside the PLC program. Once this has been done, you can isolate any single module and use a program monitoring device to monitor its internal status.

 

Power problems

PLCs require a steady stream of power to function effectively. Loss of power can be caused by many factors such as regional blackouts, poor connections, grid failure and damaged cables. This can cause malfunctions and data loss which can negatively impact your entire automated system. To avoid this, install backup power sources that come into effect when the main source is compromised.

 

Electrical noise interference

Radio frequency interference (RFI) and electromagnetic interference (EMI) are common issues that can affect the performance of a PLC. If there is another large motor or machine nearby the PLC system, the risk of foreign signal interference can increase. If you’re experiencing issues, this might be the cause. Reduce the potential for signal interference by improving shielding, grounding and power conditioning.

 

Memory corruption

External factors can result in memory corruption within the PLC system. This can cause the coding to become unreadable which can result in downtown or rebooting issues. Ensure all of the system data is backed up in a redundant storage device that’s kept in a safe place (avoid places where there is interference, humidity, or high temperatures).

 

PLC maintenance tips

PLC systems play a vital role in industrial automation. Downtime can be extremely costly and detrimental to a business. Moreover, sourcing spare parts can be challenging and time consuming (Preferred Spares provides a range of industrial automation spare parts from top manufacturers from around the globe).

Implementing a proper maintenance schedule for a PLC system is required to reduce risks and increase the longevity of units. Here are some actionable tips when it comes to PLC maintenance:

Ensure your PLC program is backed up

During routine maintenance checks, be sure to back up your PLC program to prevent unnecessary downtime in the event you have to replace it. If your PLC ceases to function and you require an entirely new system, you can simply download the backup file onto the new unit.

 

Check battery condition

Ensure the battery is in good condition. If any lights are flickering, it might indicate it’s time to change the battery. Doing so will help you to avoid downtime and data loss in case the main power source is depleted.

 

Check environmental and operating conditions

Regularly check environmental conditions such as temperature and humidity, as these play an important role in maintaining the functionality and lifespan of PLC components. Ensure there is adequate airflow into the PLC cabinet to prevent overheating.

 

Ensure I/O modules are tight fitting

It’s important to ensure each connection in the PLC system is tight-fitting, particularly I/O modules. Loose connections can cause damage to components and result in operational problems.

 

Check operating voltage

Be sure to monitor the input voltage powering the PLC system. Too high voltage can cause power spikes which can lead to downtime.

 

Clear dust, debris, and buildup

In harsh industrial environments, the buildup of dust and debris inside machinery is difficult to avoid. Be sure to regularly clean equipment to ensure units don’t become clogged. Failure to do so could result in downtime or more severe catastrophes such as short circuiting which can cause permanent damage. 

 

Perform updates when required

Stay on top of any software patches or upgrades that are required to ensure your PLC system is always up to date. 

 

Discover the range of PLC systems and industrial automation parts from Preferred Spares

As one of the leading industrial automation companies in the UAE, Preferred Spares provides a range of PLC system spare parts from the world’s top manufacturers. 

If your PLC system requires a new component, or you need an entirely new unit, Preferred Spares guarantees high-calibre parts at affordable prices, as well as fast delivery to ensure your system stays up and running with minimal downtime. 

 

Visit the Preferred Spares website to view the full range of industrial automation spares or contact the team to book a consultation for expert PLC installation advice today or