Sequence & interlock logic
Translate the agreed process into operating modes, start/stop sequences, permissives and fault handling.
SERVICE 01 / PLC & HMI PROGRAMMING
Control logic with an operator’s perspective.
Develop a new machine control system or make a carefully scoped change to an existing one. We bring operating sequences, equipment states and operator screens into one coherent engineering scope.
What the scope can cover
HMI screen development
Organise overview screens, parameters, equipment status and alarms around the operator’s tasks.
Drives & communications
Define the device list, supported interfaces and information exchanged between the controller, drives and interface.
Existing-system changes
Review available source files and agree which existing behaviours must remain unchanged before modifying the program.
Agree the deliverables.
- PLC and HMI project files, subject to the agreed platform and source-delivery terms
- I/O and communication mapping within the contracted scope
- A description of operating modes, interlocks and alarm behaviour
- Test records and an agreed commissioning / handover checklist
A SUITABLE STARTING POINT
For equipment builders adding a control package, owners modifying an existing machine, or integrators who need a defined PLC/HMI software scope.
Review checkpoints
Use these questions to define the test scope. They are planning guidance, not a statement that an unrelated installation has already passed these checks.
Operating modes
Review manual, automatic, start/stop and restart behaviour against the agreed action list.
Permissives and fault handling
Identify the expected response to a missing condition, device fault and loss of a required signal.
Interface consistency
Match commands, feedback, data types and HMI units with the actual I/O and communication list.
Preservation during changes
Check the functions explicitly marked to remain unchanged and keep a verified pre-change backup.
What shapes the quotation
- I/O count, equipment count and the number of distinct operating sequences
- Number of HMI pages, parameters, alarm groups and communication devices
- Usability of the existing source files, drawings and software versions
- Available test hardware, onsite support and the agreed change/review rounds
Examples behind this scope
Scope boundary
Machine safety, hardware suitability and onsite validation must be assessed for the actual application. Remote development does not replace an authorised person checking the physical equipment.
RELATED EXPERIENCE
Multi-level conveyor control
Mitsubishi FX5U control for a multi-level belt conveyor, with grouped operation, individual manual functions and drive-state monitoring.
Read the project story
Historical project photograph showing grouped variable-frequency drives. The image is not evidence of current operating condition.
START WITH THE REQUIREMENT
Tell us what your
equipment needs to do.
A process description and an equipment list are a useful starting point.