Electrical control is rarely the part of a custom machine that people argue about first. Layout, throughput and handling get the attention, and the control panel arrives later as a box with a part number. That order is where rework starts. On non-standard automation and steam cleaning equipment, the control system is what carries the process conditions, the safety rules and the acceptance evidence, so the quality of the specification you hand over decides how much of the build has to be redone.
The examples below describe our own engineering sequence on non-standard equipment. Process figures are illustrative and come from internal design reviews, not from any customer machine. Your own machine needs its own numbers.
The inputs that decide the control architecture
Before anyone selects a controller, we need a stable picture of what the machine has to control. Four inputs usually set the architecture, and each one has a concrete form on a drawing or a sheet.
1. The process recipe, as parameters and a sequence
A description such as "heat to temperature and hold" is not a specification. We ask for the process split into states, with the parameter that closes each state: heat to a setpoint, dwell for a time, apply, release, cool, unload. For a steam cleaning machine that means how steam is produced, how it is delivered to the gun, how the vacuum recovery runs alongside it, and what stops heating when the water tank runs low. A machine whose cycle is only a start button and a green lamp tells the controls engineer nothing about what to interlock.
This is also where our product development services for steam cleaning equipment work begins. Feasibility is judged on whether the process can be held repeatably by the control layer, not on whether the mechanism moves.
2. The I/O list, and what each signal actually does
A control system is an I/O list plus logic. Send us a list, not a sentence. For every signal we want: the device, the signal type (digital input, digital output, analogue, pulse), the voltage it works at, and what the machine should do when that signal is absent. The last item is the one people skip. A missing flow signal during heating and a missing flow signal during loading are two different reactions, and both have to be written down before wiring.
Motion and vision work needs the same treatment. For positioning: axis count, travel, required repeatability, whether homing is done per shift or per part. For alignment: what the camera is looking at, the tolerance it must resolve, and where the rejected part goes afterwards. Our semiconductor process equipment lines are specified this way, because bonding and laminating tolerances are set by alignment feedback, not by mechanical stops alone.
3. Safety functions and their stop behaviour
Tell us what has to stop, who can reset it, and what may stay powered while the machine is stopped. Guard doors, emergency stops, overheating, over-pressure, low water and loss of vacuum are separate functions with separate consequences. A fixed steam cleaning machine, for example, runs heating, pressure and water supply at the same time, so the protection set is written as independent conditions rather than one shared alarm. The behaviour of an interlock after a fault — hold, stop, or allow manual jog out — is a specification item, not a commissioning decision.
4. Site conditions for power, utilities and consumables
The supply the machine will actually see changes the panel: available voltage and phase, the breaker rating at the point of connection, compressed air quality, water supply pressure and connection type, and the floor space the cabinet and handles must fit into. Machine dimensions and how the operator reaches the controls belong in the same conversation. On mobile and hand-pushed cleaning equipment, whether the working supply comes from the mains or from a battery is decided by site conditions first, and that decision moves through the wiring, the protection design and the testing plan.
What to hand over, and in what form
A workable specification package is short but complete. We expect, at minimum:
- A process sequence with states, parameters and dwell times, including what is adjustable by the operator and what stays locked to the engineer.
- An I/O list with signal types, working voltages and defined behaviour on loss of signal.
- A safety function list with stop and reset behaviour for each function.
- Utility data: supply voltage and phase, protection devices already installed, water and air supply data, and the machine footprint and access routes.
- Traceability requirements: which parameters must be recorded, for how long, and in what format.
Where that package does not exist yet, our manufacturing automation services start at process analysis instead of equipment selection. We document the current cycle, agree the target cycle, and write the control requirements from that baseline, then carry the same information through mechanical design, electrical control, manufacture, installation and commissioning to delivery and acceptance.
How the inputs change what is delivered
Three differences show up on almost every project, and all three are decided by the inputs above.
Recipe ownership. If your engineers will change recipes without a supplier, those recipes need to be modelled as named parameter sets from the start, with limits that the machine enforces. If the recipe is fixed, the control layer gets simpler and the panel gets smaller.
Fault history. Decide early whether the machine must keep alarms with timestamps, and which ones a maintenance team can act on without a vendor. That decision affects the controller selection and the human-interface layout, and it is expensive to add after the program is written.
Staffing after handover. A line specified for a small internal maintenance team needs different diagnostics from one run by controls engineers. When in-house controls capacity is thin, integrated engineering team services cover the electrical, automation and test roles for the project, and the documentation is written for the team that takes the machine over.
The acceptance data to define before the build
The final input is the least discussed: what proves the machine is finished. Specify the tests, the conditions they run under, and the records that come out of them, before the panel is wired. On our side that means functional and performance testing, stability and safety verification, and lifetime reliability testing, with a factory testing plan agreed in advance and outputs in the form of testing records, problem lists, optimisation suggestions and factory inspection standards. Our hardware testing work is written up that way, so acceptance becomes a document review with numbers behind it rather than a demonstration.
Traceability belongs here too. If a parameter has to be recovered later for a customer audit, it must be stored by the machine, not recorded by an operator. Write that requirement into the specification and the logging design follows.
A short readiness check
- Can you state each machine state, the parameter that ends it, and what happens if that parameter never arrives?
- Does every sensor and actuator have a signal type and a working voltage?
- Is stop and reset behaviour defined for each safety function?
- Are the utility data and the machine footprint confirmed for the installation site?
- Are the acceptance tests and the records they produce written down?
If any answer is no, that gap belongs in the specification before the control design is priced. Send us the process description and the data you already have; we will mark what is missing and tell you what each missing item would change. For equipment that needs to be built to your process rather than selected from a catalogue, customised solutions cover requirement analysis through testing and verification, including OEM and export customisation.
