Automation Guide
On the field, control and automation systems are implemented using very specific tools like PLCs : tools that are usually not taught, or even mentioned, in non-technical-focused universities. However, if you're pursuing a career in industrial control and automation, hands-on experience with these tools is essential. I had to learn them on my own, and here I'm trying to share the material I wish I'd had to speed up that process. Here I will be talking about tools, programming strategies, and everything that constitutes the bridge between control theory and its application on a field computer.
Introduction & Motivation
Career planning for automation and control engineering
If you’re targeting a career in:
- Industrial automation & control engineering,
- Process control and instrumentation,
- Manufacturing IT / MES systems,
- SCADA / HMI development and integration,
- Industrial IoT and digitalization projects,
- Commissioning and field engineering (FAT/SAT).
And if you left university without knowing ISA-95 automation pyramid, or most of the key words it contains (PLC, DCS, SCADA, etc.):
| ISA-95 Level | Primary Function | Time Horizon | Example Systems |
|---|---|---|---|
| Level 4 | Business Planning & Logistics | Days → months | ERP (SAP, Oracle) |
| Level 3 | Manufacturing Operations Management | Hours → days | MES, LIMS, RTO, scheduling |
| Level 2 | Monitoring & Control | Seconds → minutes | SCADA/HMI, DCS, APC |
| Level 1 | Sensing & Manipulation | Milliseconds → seconds | PLC, PAC, PID |
| Level 0 | Physical Process | Microseconds → milliseconds | Sensors, actuators |
| Then you are starting from the same point as I did, and I have a good and a bad news for you: |
- The good news is that these things are much easier to learn than most of what is covered at university.
- The bad news is that the people (or the AIs) reading your CV expect you to master at least some of them, and are explicitly searching for key words like PLC programming (ST, LAD, FBD, etc), or even specific brands environments like Siemens in Europe (TIA portal) or Allen-Bradley in the US.
So, what you need to do now, is planning how to get experience in those levels - and don’t wait for the end of your studies. Do it asap. This actually opens a lot of doors everywhere, and I realized it a little to late.
My strategy now that I’m writing those lines is given in this note : link. While I’m following this strategy, I will write notes, and organise them here in the following sections. One section per “level”.
Level 1
PLC
A PLC is an embedded computer that holds the control and automation logic for many industrial systems - it reads sensors and drives machinery accordingly. Housed in a control cabinet, it stands out for its modularity: I/O capacity can be extended simply by adding terminal modules, which is why PLCs dominate “static” installations where cabinet space and this flexibility are assets. Moving or mobile systems (vehicles, robots, embedded machines) more often rely on specialized hardware like microcontrollers or ECUs instead - not because PLCs are less robust, but because these applications demand smaller size, lower weight, and lower power consumption than a modular PLC architecture can offer.
Siemens Technologies
Siemens is the world leader in industrial automation. About 33% of the machines on earth are controlled with their systems. Knowing their solutions opens many doors.
- Setup your Siemens trial license (Optional if your company already provides you with a license).
Codesys
Beckhoff
Level 2
HMI and SCADA systems
What are HMI and SCADA systems ?
They are interfaces for humans to supervise and interact with machines. They are conceptually very similar, and their difference lies in the way they are implemented :
| Criteria | HMI | SCADA |
|---|---|---|
| Scope | Single machine/line | Multiple machines, lines, or sites |
| Nature | Physical device (screen/panel) | Complete software/hardware system |
| Data storage | Usually no historization | Historization via database/server |
| Location | Near the machine, on-site | Often in control room or remote |
| Network communication | Limited, direct PLC connection | Integrates networks, cloud, ERP/MES |
| Relationship | Component of SCADA | Encompasses one or more HMIs |
In practice, most industrial installations combine both: local HMIs for immediate machine control, feeding into a broader SCADA layer for supervision and historization.