PLC and controls integration is the process of designing, programming, and connecting a programmable logic controller (PLC) with the rest of your industrial systems, including HMIs, SCADA, VFDs, motors, sensors, conveyors, robots, safety circuits, and upstream software like WMS or ERP.

Done well, it gives you one supportable platform your maintenance team can run, monitor, and modify without calling the original programmer.

Projects range from roughly $5,000 for a single-panel swap or small program edit to multi-million-dollar engineered systems for full plant or distribution center builds.

Most mid-sized projects (a line retrofit, an HMI overhaul, or a legacy SLC 500 migration to a modern platform) land between $40,000 and $250,000 depending on I/O count, programming hours, panel scope, and field installation labor.

Every project has two phases: planning and execution. Planning covers design, panel build, programming, and FAT, and can take anywhere from 8 to 16 week. Execution on your floor is short, and HOJ has completed multiple changeovers in a couple of days to minimize customer downtime.

Small program changes run days to two weeks, and full plant or warehouse builds run six months to over a year, driven mostly by hardware lead times.

The strongest filters are in-house engineering, not just programming, so the same team designs the panel, writes the code, and stands up the system on your floor. Multi-brand capability, so they recommend a platform and still support what you already run. HOJ recommends Beckhoff for new builds and works on Allen-Bradley, Siemens, and other major platforms when needed.

Written documentation standards as part of the deliverable: commented code, I/O lists, as-built drawings, and backup files. A clear FAT and SAT process so you see the system work before it ships.

Code ownership written into the contract, so you own what you paid for, and post-commissioning support. References from projects in your specific industry matter more than total company size.

A PLC (programmable logic controller) is a rugged industrial computer that runs a control program in a continuous loop, reading inputs from sensors and switches, executing logic, and writing outputs to motors, valves, and other field devices, typically on a 1 to 50 millisecond scan cycle.

Common platforms include Allen-Bradley ControlLogix and CompactLogix, Siemens S7-1200 and S7-1500, Beckhoff CX-series controllers running TwinCAT, and Mitsubishi MELSEC.

HOJ builds new systems on Beckhoff because it is an IPC (industrial PC), a PLC integrated into a PC. You get the added functionality of a PC with the I/O interface of a PLC.

The IEC 61131-3 standard defines four active PLC programming languages as of its 2025 edition: Ladder Diagram (LD), Function Block Diagram (FBD), Sequential Function Chart (SFC), and Structured Text (ST). A fifth, Instruction List (IL), was removed in 2025.

HOJ works almost entirely in Structured Text. ST handles both simple logic and complex math, recipes, and algorithms, while the other languages tend to suit one or the other. Beckhoff standardizes on ST, and it reads like modern programming languages, so new engineers and maintenance techs pick it up faster.

Ladder Diagram is a distant second, mostly on existing Allen-Bradley and Siemens floors. We rarely see FBD or SFC. ST is our default, but we use other languages when a project calls for it.

Yes. What makes them work together is the communication protocol, not the brand. Mixed-brand environments are common and connect through industrial protocols like EtherNet/IP, Modbus TCP, PROFINET, and OPC UA. For example, a Beckhoff controller can pass data to a Rockwell ControlLogix. HOJ has connected systems using OPC UA and EtherNet/IP implicit messaging.

The hard part is making sure the data structures match. That used to require both systems to be designed together. Today we can bridge the gap without both parties involved in the design. On one project, we got a new system talking to an existing one to keep the floor running until the full upgrade.

HOJ has upgraded SLC 500 and PLC-5 systems to modern Beckhoff controls, future-proofing the warehouse floor. The sequence is to audit the existing program, document the I/O, build the new panel offline, schedule a planned outage, cut over, and commission.

Every migration has a point of no return. Once the old wiring comes out and the new wiring goes in, there's no switching back to the old controller. That's why we test and verify everything beforehand and work through every high-risk scenario before cutover day. We've done this before, we know where the pitfalls are, and we don't make the jump until we're confident in the change.

Many PLC platforms offer limited simulation. Testing means manually triggering inputs and stepping through logic, and interfaces to other systems often can't be tested until cutover. Beckhoff allows full simulation, so we run the new system and its interfaces before we touch your floor. If an issue does come up on site, we already know where to look.

The biggest risk is usually network infrastructure: firewalls and whether your network allows the connections the system needs. We involve your IT team early to resolve that before cutover. New or first-of-its-kind functionality carries more risk, so we engineer those risks out before implementation.