How to Monitor Older Machines Without a PLC

Peakboard monitors older machines without a PLC or OPC UA too – via external clamp sensors that measure power consumption and derive whether a machine is running, idle or stopped. That is non-invasive machine monitoring: no intervention in the controller, no PLC programming, installed within hours with no machine downtime.

The problem: older machines without a digital interface

In many manufacturing plants the machine park is mixed. Next to modern CNC systems with OPC UA and Siemens PLCs stand presses, wire machines, welding systems or machining centres from the 1990s or 2000s. These machines have no modern controller, no digital interface and no OPC UA server. Reading machine data directly is not possible.

The consequence: these machines are invisible in monitoring. Stoppages are only noticed on the next walk-through. OEE cannot be calculated automatically for them. The whole of production monitoring has blind spots.

The solution: external clamp sensors

For older machines without a PLC or digital interface there is a simple, non-invasive solution: external clamp sensors (current transformers, CT sensors) attached to the machine's power cable. They measure the electrical current and deliver three relevant states:

• High power consumption: machine running under load (producing)
• Low power consumption: machine idle (switched on, not producing)
• No power consumption: machine switched off or stopped

These three states are enough to capture automatically when a machine is producing, when it is stopped and how long the stoppage lasts. Peakboard receives the power signal, processes it and shows the machine status in real time on the shop floor display.

Combining with manual operator input

Power sensors detect whether a machine is running or stopped – but not why. For the fault reason you need the operator. Peakboard combines both data sources: when a sensor reports a stoppage, a touch prompt appears on the display – the operator enters the reason in seconds, without leaving the workplace. The result: automatic stoppage capture plus contextual reason, stored in an audit-proof way.

Mixed machine parks in one overview

Peakboard supports mixed machine parks: modern equipment is connected via OPC UA or S7 direct access, older equipment via sensors. All data flows into the same dashboard – one unified overview of the entire machine park, regardless of the age or manufacturer of the equipment.

Connection to shop floor management

Older machines can thus become part of machine monitoring too. The stoppage data feeds into downtime tracking and makes older equipment visible for OEE calculation and the shop floor meeting.