How One Small Functional Block Affects Industrial Equipment Maintenance

Software standardization in Russia remains underdeveloped. Integrators developing automation systems often do not think about the consequences for equipment maintenance. As a result, software can negatively affect the work of engineers, complicate fault diagnostics, modernization and other processes related to equipment operation.

In this article, I will show you how implementing just two simple functional blocks can make a huge difference and make systems much easier to maintain.

Simple solutions – big changes

We are talking about two simple software blocks that play a key role in the operation of PLCs (programmable logic controllers). The first block copies the state of the inputs to a specific area of the controller's memory, be it markers or data blocks. This block must be called at the beginning of the program cycle. The second block, on the contrary, outputs data from memory to the controller's outputs and is called at the end of the cycle.

To make things easier to understand, we will focus on the first block only, as their logic is identical.

Various options for working with PLC inputs

Let's consider several ways of organizing work with PLC inputs using Siemens controllers as an example. However, the proposed solutions can be applied to PLCs of any manufacturer.

Classic assignment of inputs to markers.
Example for Siemens PLC:
```
I10.1  
=M 10.1
```
Direct use of input addresses in the right places in the program.
Using indirect addressing to copy data from inputs to a data block.
The use of indirect addressing throughout the program, which eliminates the mapping of addresses to cross-reference.

Practical example

Let's imagine a situation: one input in the PLC input module has burned out, and there is no replacement in stock. The most obvious solution would be to rewire the wire to another input and change the address in the program. However, the implementation of this solution directly depends on the way the inputs are processed in the PLC.

Option 1: If the inputs are rewritten to markers, the change will take only a minute, and the system will continue to operate stably. Restoring the original configuration after replacing a module will also not require significant time.
Option 2: The entry address will have to be changed in each part of the program where it is used, which can take a significant amount of time. The risk of errors increases, especially in a hurry, which can lead to system failures or incorrect actions.
Option 3: The change is possible quickly, as in the first case, but requires careful consideration, since the use of indirect addressing can lead to confusion when upgrading the system later.
Option 4: The most difficult option, since you will have to manually check the entire program for references to inputs. This takes a lot of time and increases the likelihood of errors.

Benefits of standardization

Using the first option, which involves systematically copying input data into specific memory areas, has a number of significant advantages.

Fast diagnostics and troubleshooting. With structured recording of inputs and outputs in sections with comments, engineers can quickly find the necessary signals without having to refer to electrical schematics.
Simplification of commissioning works. Standardized blocks prove to be a great tool for checking inputs and outputs during I/O check.
Quick replacement of faulty sensors. In systems with signal duplication, if a sensor fails, the signal can be quickly rerouted to a working sensor, ensuring minimal line downtime. Major repairs can be postponed to a more convenient time, such as a scheduled shutdown.
Improving operational safety. Standardization of blocks helps to minimize human errors during repairs and upgrades, reducing the risk of incorrect actions by engineers.
Accelerating modernization. Structured work with inputs and outputs allows you to quickly adapt the program to new tasks or equipment without rewriting significant parts of the code.
Improving the qualifications of engineers. Engineers who work with clearly organized and standardized code learn the system faster, which increases their efficiency and speeds up the workflow.

Conclusion

As we can see, the introduction of simple function blocks into PLC software significantly improves maintenance and reduces equipment downtime. These changes contribute to increased safety, faster upgrades, and easier work for engineers.

Software standardization is becoming an important tool in the development of integrator companies, allowing them not only to reduce repair time, but also to improve the quality of equipment maintenance. In the conditions of growing competition in the automation market, such measures are becoming an important element of successful and sustainable growth.