Home / Projects / Drum plant retrofit

Drum plant blending control retrofit — project outline.

An illustrative outline of what a drum plant process blending control retrofit typically involves: assessing what can safely remain, replacing end-of-life controls where needed, and scheduling the work around an off-season cutover.

This is an outline, not a delivered case study. It describes the shape of a typical engagement of this kind: the questions we ask up front, the work involved, and how the cutover tends to be sequenced. Actual scope, schedule, and outcomes vary by site.

Typical situation

An aging plant, a glitchy computer, and a busy paving season ahead.

Drum plants with legacy controls are often mixed environments: some devices remain practical to support, while the PLC, HMI, or operator computer may be reaching the end of its useful life. A common driver is the realization that another paving season on the existing controls is a real risk.

The constraint tends to be the same: a winter shutdown window and a non-negotiable paving start date in the spring.

What the work typically involves

One control platform, one HMI, one alarm philosophy.

A control platform selected with the client, which may include a new PLC, suitable existing I/O, or a staged migration path
Remote I/O or device integration over PROFINET or EtherNet/IP, sized to the existing field wiring and hardware condition
Operator HMI panels in the operator trailer (typically a primary + spare)
An asphalt-oriented HMI built from our reusable components — mix overview, recipes, totals, calibration
Alarm rationalization aligned with ISA-18.2, done with plant staff
An on-prem SQL Express historian, with optional cloud KPI feed
VPN-based remote support arranged in place of exposed RDP
Operator training and a printable quick reference

How a cutover is usually sequenced

From shutdown to first paving truck.

The exact length depends on the plant. The phases below are usually present in some form.

Phase 1 · Strip & pre-wire

Old hardware is removed only where needed; new panels, controllers, or remote I/O are mounted where required, and serviceable field wiring is carried forward.

Phase 2 · Loop checks & burner

Every I/O point is exercised. Drive and burner interlocks tested, ideally with the burner OEM on site.

Phase 3 · Dry-run mix production

A small number of mix recipes produced to silo. Totals reconciled against the truck scale before any customer trucks are loaded.

Phase 4 · Operator dry-run

Operators run the full HMI through a typical paving morning — start-up, mix change, silo drop — before the first paving day.

Phase 5 · Hand-off & first paving day

We aim to be on site for the first customer truck, with remote support arrangements after that.

Common project specs

PLC: Siemens S7-1500, AB CompactLogix / ControlLogix, or suitable existing architecture
I/O: existing or new remote I/O sized to the plant
HMI: FactoryTalk Optix, WinCC Unified, or equivalent
Network: PROFINET or EtherNet/IP
Historian: SQL Express on a plant server
Cloud: AWS, optional

Questions we usually ask up front

What is the current PLC and HMI, and roughly how old?
How long is the shutdown window?
What is the non-negotiable start date?
What dispatch / ticketing system is in use?
Are the field wiring drawings up to date?
What does the operator group look like on day one?

Service areas this project draws on

⚙

Planning something similar?

If a drum plant retrofit is on the radar, a short conversation about the shutdown window and current PLC platform is usually a good place to start.

Get in touch