Custom electronics and control systems for industrial automation

When does a custom board alongside a PLC make sense?

If an off-the-shelf PLC expansion module meets the requirement, it can shorten development time. Custom electronics are considered when a repeated machine family needs a common I/O arrangement, a custom sensor interface, a compact installation or a communication function unavailable in standard modules. The decision is based on more than the board's unit cost; design effort, assembly, testing, spare parts and field maintenance also count.

For example, in a machine whose main movements are controlled by a PLC, the custom board may handle measurement and communication only. In another project, a defined operating sequence may run in the board's embedded software. Safety-related functions and control responsibilities are clarified with the relevant system teams at the outset. This defines when the new unit operates independently and when it waits for the main controller's decision.

• Comparison of ready module and custom design with the same scope
• Reuse and revision plan according to machine family
• Clear definition of control and safety responsibilities

Guide to evaluating a custom board for an automation system →

We design industrial I/O and sensor interfaces according to the field

A 24 V digital input, PNP/NPN sensor, 0–10 V voltage signal, 4–20 mA current loop and encoder connection require different input circuits. Each channel's electrical type, measurement range, sampling needs, cable length and connection arrangement are defined. Design depends on precision and calibration for analogue measurements, frequency and minimum pulse width for pulse inputs, and load current and switching behaviour for outputs.

The measurement circuit's operation alongside motors, contactors and valves in the control cabinet is assessed. Supply variations, possible miswiring, reverse polarity, isolation requirements and cable-borne disturbances are incorporated into the hardware architecture. Connector pin assignments are considered alongside the machine's wiring harness. A disconnected sensor or invalid reading is presented in software and on the operator display as a state distinct from normal process data.

• Analog measurement, digital input and pulse counting
• Driver and output interfaces suitable for the load
• Supply, protection, isolation and service access

Meaningful integration of Modbus, CAN and machine data

An RS485 connection alone does not make devices communicate correctly. For Modbus RTU or Modbus TCP, addresses, register maps, data types, scaling and write permissions are defined. A CAN-based system also requires an application protocol and message dictionary. A sensor reading's unit, validity and update time matter as much as its numerical value; carrying different units under the same name can cause integration errors.

In projects where machine data will be transferred to the server, local gateway, Ethernet, Wi-Fi or cellular connection are evaluated according to field conditions. Sending a command, receiving it by the device, and physically executing it are separate events. Confirmation and outcome information should demonstrate this distinction. How to keep records when the connection is lost and how to handle old commands when reconnected is also added to the interface documentation.

• Protocol converter and custom gateway development
• Data dictionary, timeout and error states
• Local logging, server API and command result tracking

We verify industrial automation software with real machine

Control software defines more than the normal operating cycle. It also covers startup, parameter loading, sensor readiness, stopping and restart after faults. If recipes or machine parameters are stored, their valid ranges and when changes take effect are specified. The software version, board revision, device identity and fault history are made accessible for servicing.

The operations that the operator can perform on the button, indicator, screen or HMI interface are separated from the settings that the maintenance team can access. Instead of a vague error code, it is shown which input is not expected and which check can be made. The position of the screen and buttons is tested along with the mechanical layout. Usage details such as gloves, viewing angle and working distance contribute to the easy use of a technically correct system in the field.

• State machine and behaviour after interruptions
• Parameter, recipe and service interfaces
• Error and process information that the operator can understand

Embedded software development for control and communication →

We adapt the electronic circuit board to the mechanical structure of the machine

Board size, connection direction and mounting holes are not details determined at the final stage. Use in the electrical control cabinet, mounting on the machine body or a standalone interface box creates different mechanical requirements. Cable bending space, ventilation, sequence of removal during service and access to the programming connection are controlled in the internal layout. If necessary, the board, connector and wiring harness are evaluated together on the 3D prototype.

Parallel progress of electronic prototype development and mechanical design reduces pre-production repetitions. The layout, labeling and mechanical fixing that prevents mixing of similar connectors also serves the maintenance process. Dust, humidity, vibration or temperature targets are derived from usage conditions; The sample and test with which these goals will be verified are shown in the project plan.

• CAD layout suitable for electrical control panel, box and machine
• Wiring harness, connector and mounting access
• Prototype evaluation according to real use environment

From first prototype to pilot machine and production testing

On the first board, the power supply, inputs, outputs and communication are brought up separately. Scenarios are then tested with actual sensors and loads. Power loss, communication loss, sensor disconnection and parameter limits are included in the test list. As the cycle and wiring are validated on the pilot machine, findings are recorded against the hardware revision and software version. Acceptance means performing the defined task under the specified conditions, not merely powering on.

Production preparation includes the bill of materials, sourcing alternatives, programming steps and functional tests. Design validation and inspection of each manufactured board are separate processes, with test points and fixture access planned accordingly. Rapid prototype PCB fabrication and assembly support are provided only as part of customer projects developed by VOMRO; we do not offer general PCB fabrication or assembly orders outside those projects.

• Acceptance tests matched to requirement
• Pilot integration and traceable revisions
• BOM, programming and production control plan

Confidentiality, source delivery and the initial project discussion

At your request, we sign a non-disclosure agreement (NDA) before you share the machine's operation and proprietary technical details. The customer project is not turned into VOMRO's own product catalogue. Project source code, electronic and mechanical design files and technical documents are delivered at completion. Editable source formats, build environment and deliverables list are defined at the outset; third-party component licence terms are explained separately.

For the first conversation, you can share what the machine does, the existing PLC or controller, the sensor and load list, the supply conditions and the function you want to add. The target production quantity, layout limit and access to the pilot machine also clarify the scope. If the drawings are not ready, we create the requirements together based on the usage scenario. The proposal is prepared so that the development deliverables and how they will be accepted are visible.

• NDA on request before technical details are shared
• Source, EDA/CAD and technical document delivery
• Concrete project scope via signal list and pilot