Control System Design Philosophy
Below presents the general procedure executed for a rigourous and reliable PLC based Industrial Control System. Depending on time and system requirements, more steps may be added or removed.
- Control System Design
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- Consulting the customer requirements and feasibility of the implementation.
- Deciding on equipment, communication protocols depending on application.
- Developing interactive P&ID diagram w.r.t. the control system as additional documentation.
- Development of FDS and SDS after decisions made.
- Constructing Control Loops and diagrams for each actuated property.
- Tree structure for the Macro-Sequence for deterministic execution.
- Re-usable API's for Modbus, TCP/IP, serial and other communication protocols for seamless interfacing with the PLC.
- State machines for actuated properties and actuation paths.
- Possible Computer based control with RTOS's, or maintence diagnostics on distributed electronics such as a Raspberri Pi.
- Control System Installation & Commissioning
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- Changing code and documenting it in necessary documenation when commissioning
- Mapping out I/O's for better code structure and easier testing.
- Development of simulations where possible.
- Writing up of FAT documentation to suffice the agreed FDS w.r.t software state.
- Testing of comms to necessary instrumenation and drives, prefrably before FAT.
- SAT test on site as subset of FAT and commissioning up to this point.
- Proactive Maintenence
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- Well defined backup methodology and done often.
- Changes done sparingly, and in addition to current code rather than mutating current code after SAT.
- Development of common faults list and method statements to deal with said issues.
- Method statements for configuration, troubleshooting and customisation where possible.
- SDS to be explict with respect to code structure, to prevent miscommunication.
- Updating and following up mods in relevant documentation to keep everything up-to-date.