Direct answer
Require a code standard, documented interface signal list and delivery of commented source code as a contractual deliverable.
What this discipline delivers
- Machines that cannot exchange state or fault signals
- Undocumented or password-locked PLC code
- Every modification requires the original supplier
- No standard interface signal set between machines
- Software changes made on site with no version control
Method and stages
Interface signal standard
A defined signal set every machine must implement for line coordination.
Code structure standard
Modular, commented code with naming conventions.
Simulation testing
Logic verified against a process model before commissioning.
Source code and licence delivery
Commented source, project files and licences handed over.
Engineering and project considerations
- Password-protected code is a lifetime cost, not a supplier's IP right, unless agreed
- Version control and backup procedures for machine software
- Change management for on-site modifications
- Test coverage for fault and recovery paths, not just the happy path
- Compatibility with plant historian and MES tags
What to prepare before engaging engineering companies
- Plant PLC standard, if one exists
- Interface signal list for line coordination
- Required data tags and formats
- Software handover requirements in the contract
What to measure
Frequently asked questions
Should we insist on source code?
Yes for machines central to your operation. Without it, every future change and diagnosis is a supplier transaction.
Related engineering knowledge
Independent, buyer-side and supplier-neutral
Global B2B Group does not sell machines and does not represent equipment manufacturers. This material is published to help industrial organisations define the problem, prepare the specification and structure the investment before engineering partners are selected.