Choose an ABB AC500 PLC in five steps: decide the family by application (AC500-eco for compact machines, standard AC500 for larger or communication-heavy systems, AC500-S when a safety PLC is needed, AC500-XC for extreme environments), prefer a current V3 CPU for new designs, count I/O and add about 20 % spare, list every protocol you need, then confirm the final choice against ABB's current product selection data.
- Family first: eco, standard, safety (S) or extreme conditions (XC)
- New projects: prefer V3 CPUs; V2 eco CPUs (PM55x/PM56x) suit existing machines and training
- Add 20 % spare I/O and keep a free slot for future modules
- Communication needs often decide the CPU more than the I/O count
This guide is the planning step that comes before Lab 1. It is written for engineers and students choosing hardware for a new machine, a retrofit or a training kit. Product ranges change, so treat model lists as orientation and confirm part numbers with ABB or your distributor.
Step 1: Pick the AC500 Family
| Family | Typical application | Strengths | Consider when |
|---|---|---|---|
| AC500-eco | Compact machines, conveyors, pumps, HVAC, OEM series machines | Cost-effective, onboard I/O, Ethernet + serial | Up to a few hundred I/O, standard protocols |
| AC500 (standard) | Larger machines, process cells, plant-level control | More performance and memory, communication modules, high I/O counts | Many fieldbus networks, large programs, redundancy-style needs |
| AC500-S | Machines that need programmable functional safety | Safety CPU and safety I/O in the same system | Risk assessment requires a safety PLC (E-stop, guards, light curtains in logic) |
| AC500-XC | Harsh environments: wide temperature, vibration, humidity, altitude | Extreme-condition variants of the AC500 range | Outdoor, marine, mining, water infrastructure |
Step 2: Understand V2 and V3 CPUs
| Generation | Examples | Engineering | Use it for |
|---|---|---|---|
| AC500-eco V2 | PM554-ETH, PM556-ETH, PM564-ETH, PM566-ETH | Automation Builder with the CoDeSys 2.3-based editor | Existing machines, spares, training kits (used in this lab series) |
| AC500-eco V3 | PM50x2 range, e.g. PM5032-T-ETH, PM5072-T-2ETH | Automation Builder with the CODESYS V3-based editor | New compact machine designs |
| AC500 V3 (standard) | PM56xx range, e.g. PM5630-2ETH, PM5670-2ETH | Automation Builder, CODESYS V3-based | New larger systems, communication modules |
Ladder, ST, I/O mapping and Modbus concepts in Labs 1–20 apply to both generations. Menus and some library blocks differ; each lab notes the V2/V3 difference where it matters.
Step 3: Count I/O with the Interactive Selector
ABB AC500 PLC selector
Enter your I/O count and needs. The tool adds spare capacity, suggests a family and generation and sizes S500-eco expansion modules. It is a planning aid, not an ABB configurator.
| S500-eco module | Channels used by the selector |
|---|---|
| DI562 | 16 DI |
| DO562 | 16 DO transistor |
| DX561 | 8 DI + 8 DO (used when both are small) |
| AI561 | 4 AI |
| AO561 | 2 AO |
Step 4: List Communication Needs
| Need | Typical solution | Check |
|---|---|---|
| Programming + HMI | Onboard Ethernet | Enough Ethernet ports (one, or two for separate networks) |
| Drives on serial | Modbus RTU on onboard RS-485 (Labs 19–20) | Number of drives and poll time |
| SCADA / other PLCs | Modbus TCP, OPC UA (on supporting CPUs) | Protocol support in the CPU datasheet |
| PROFINET, EtherCAT, PROFIBUS, CANopen | Communication modules on standard AC500 CPUs | Module availability for the CPU family |
| Remote I/O | Communication interface modules + S500 I/O | Distances and cycle time |
Step 5: Final Selection Checklist
| ID | Check | How to check | Pass criterion | Result |
|---|---|---|---|---|
| Selection checks | ||||
| P-01 | Family | Compare Step 1 | Family fits machine, safety and environment | |
| P-02 | Generation | Prefer V3 for new designs | Decision recorded | |
| P-03 | I/O + spare | Selector result | ≥ 20 % spare, free slot kept | |
| P-04 | Communication | Step 4 table | All protocols covered | |
| P-05 | Power budget | Sum CPU + module consumption | 24 VDC PSU with margin | |
| P-06 | Software | Automation Builder edition | Basic covers programming; licences for extras | |
| P-07 | Confirm | ABB / distributor | Part numbers and availability confirmed | |
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
| Ran out of I/O during commissioning | No spare planned | Plan 20 % spare and a free slot from the start |
| Cannot add PROFINET to the eco CPU | Family chosen on I/O count only | Check communication needs before choosing the family |
| Safety functions written in standard PLC | Safety requirement not assessed | Do the risk assessment; use AC500-S or safety relays |
Frequently asked questions
What is the difference between ABB AC500 and AC500-eco?
AC500-eco is the compact, cost-optimised range for smaller machines. Standard AC500 offers more performance, memory and communication options for larger systems. Both are programmed with Automation Builder.
Which ABB PLC is best for beginners?
An AC500-eco CPU with a few S500-eco modules. It is affordable, uses the free Automation Builder Basic edition and covers everything in this 20-lab series.
Should I choose a V2 or V3 AC500 CPU?
For new designs, choose a current V3 CPU. V2 eco CPUs such as PM564-ETH are still common on existing machines and in training.
What is AC500-S?
ABB's safety PLC range: safety CPU and safety I/O modules for functional safety applications within an AC500 system.
How much spare I/O should I plan?
About 20 % per signal type, plus at least one free slot for a future module.