Automation control projects, no matter how large or small, commonly start with ambitious specifications: the system must fill all requirements, function with perfect efficiency, interoperate with existing devices, require zero maintenance, cost nothing, and be completed immediately.

Speed is crucial for success in a field with demanding requirements and crushing competition. Professionals may work with a variety of devices from a number of PLC manufacturers, yet most have a preferred brand or platform they return to repeatedly.

This is because familiar tools are faster. You know the hardware range, the software, what to expect, and who to call. For this reason, selecting the manufacturer behind a controller brand is a major decision and is every bit as important as CPU and I/O requirements.

Here are 5 factors to consider when making that selection

1. The PLC: Broad Range of PLCs

A selected vendor should have a complete product range that can meet customer requirements. PLCs must supply sufficient memory to support I/O, log and manipulate historical data, and execute the control program. Where execution speed is critical, CPU processing speed must also be considered.

Sector standards also matter. Applications may need to comply with hazardous environment standards, CFR-21.11, or food-and-beverage requirements. Space constraints can make PLC + HMI all-in-one controllers advantageous, especially when onboard or snap-on I/O modules reduce wiring and save panel space.

2. Communications: Data Communication & More

Flexibility is key: the more protocols a PLC brand supports, the better it can interoperate with existing applications and third-party devices. Important industrial data communication protocols include MODBUS, CANopen, CAN Layer2, and EtherNet/IP. Some brands also support SNMP and FTP.

It is also useful when the manufacturer provides software utilities for implementing proprietary third-party protocols, whether over serial RS232/485 or TCP/IP. Web server access, VNC, SMS messaging, email alerts, and GPRS/GSM modem support can increase data visibility and make remote access easier.

3. Programming: Look for Intelligent Software

Saving time is the primary benefit of intelligently designed software. Ease of use matters because ergonomic design reduces the time spent searching for elements. Re-usability also matters: whether you are programming Ladder or C functions, designing HMI screens and web pages, or creating custom controls, the ability to re-use work across projects saves time.

4. Maintenance: Service and Support

Choose PLC manufacturers that offer a high level of customer care. Technical and sales support should be prompt and easily available. Personal support, rather than automated systems, can make the difference in meeting deadlines and retaining customers. Support documents, specifications, and guides should also be readily available at no additional charge.

5. Cost: Total Cost of Ownership

Cost is not limited to the purchase price of the PLC. Development costs and future maintenance costs can make or break profit margins. Selecting a PLC also means selecting the company that stands behind it, and that long-term choice can have a major impact on success in industrial automation projects.