The need and approach
A machine can operate normally while business software has no visibility into its state, cycle count or faults. Access depends on the PLC manufacturer, model, firmware, communication load and the signals that may be read.
Data flow
PLC → approved read interface → collector → normalised event → application API.
A register address alone does not define a measurement. Data type, scaling, signedness, byte and word order, and units must be mapped. Polling frequency is selected with the controller and network load in mind.
Illustrative workflow
A production line exposes running, waiting and fault signals. State transitions receive timestamps. Loss of communication is not classified as machine downtime.
Questions for discovery
- What are the PLC model and firmware?
- Is a documented register or tag list available?
- Is the scope read-only or are writes required?
- What polling load is acceptable during production?
- Who authorises access and maintenance changes?
Limits and field conditions
Read-only access without changes to control logic is preferred. Writes and commands require a separate risk assessment and site approval.
Common questions
Can existing equipment be used?
Suitability depends on the device interface, manufacturer documentation, access permission and a field test. Start by sharing model details and the signals that are available.