The later an error is found, the more expensive it is. An address error caught at the drawing desk takes a minute; the same error found on site, after the cables have been pulled, costs a shift of installation. The moment an error is caught is the cost itself.
When should the check start?
In the classic approach, the check happens right before commissioning, mostly with the naked eye. An engineer works through the pages one by one; fatigue, deadlines and the temptation of a quick glance decide what is found and what is not. The result: some errors slip through to the field, and the field reworks them.
Design Rule Checking (DRC) reverses this: the check runs as soon as the drawing is done, against a rule set, and every time. The human eye confirms; the machine does the searching.
What EupCAD's rule set catches
EupCAD's design rule check inspects the project's own data and reports the findings at Error / Warning / Info levels. Some of the types it catches:
- Address conflict — two or more signals are mapped to the same PLC address.
- Short circuit — two different potentials are electrically joined.
- Protection mismatch — the motor's current and the thermal breaker's range do not agree.
- Cable ampacity — the cable cross-section does not carry the rated current.
- Missing partner — a potential is sent but no receiver exists (or vice versa); terminal duplication.
- Data defects — several coils on the same tag, a contact without a coil, a missing device record.
Every finding is listed with the device tag and the page number; the "where?" question is answered in the report.
Practical scenario: the final pass before installation
The day before installation, the engineer runs the check and reads the report. Three errors on the list: an address conflict, a motor/protection mismatch, a missing device record. All three are fixed in the office, within minutes. The field crew starts commissioning with a clean project; the "why does this address appear in two places?" discussion never happens.
Next step
In the demo project (ZONE1_PUMPS), run the design rule check: see the findings sorted by level, device tag and page number. To try it on your own panel, add a device and assign it an address that is already in use — and watch the conflict appear in the report.