Start with the operating requirement
A detector input is useful only when its electrical interface, event meaning and failure behavior are defined together. Begin with the site, intended operation and authority requirements. Record assumptions beside the requested configuration so the supplier, integrator and installer are reviewing the same system. The article is a buyer's planning resource; final design, compliance and operating decisions remain project specific.
Information to define before quotation
| Field | What to record | Why it matters |
|---|---|---|
| Input type | Dry contact, pulse, serial message or network object | Prevents an electrical output being mistaken for a data interface |
| Electrical limits | Voltage, current, isolation and common reference | Protects both detector and controller input hardware |
| Event meaning | Presence, passage, occupancy, fault or heartbeat | Lets the controller and central system interpret the same event |
| Timing | Minimum pulse, debounce, latency and update interval | Avoids missed calls and unstable transitions |
| Failure state | Open circuit, short circuit, stale data and lost link | Defines the response that must be tested |
Use a controlled review sequence
- Input type: Dry contact, pulse, serial message or network object Prevents an electrical output being mistaken for a data interface
- Electrical limits: Voltage, current, isolation and common reference Protects both detector and controller input hardware
- Event meaning: Presence, passage, occupancy, fault or heartbeat Lets the controller and central system interpret the same event
- Timing: Minimum pulse, debounce, latency and update interval Avoids missed calls and unstable transitions
- Failure state: Open circuit, short circuit, stale data and lost link Defines the response that must be tested
Give every important item an owner and a document reference. Where a value comes from a drawing, tender, authority instruction or product datasheet, identify that source and revision. Mark unresolved items rather than filling gaps with a catalogue assumption.
Build acceptance around observable evidence
Translate the approved requirements into checks that an independent witness can repeat. State the test setup, equipment identity, initial condition, expected result, measured or observed result and any deviation. Keep photographs, data exports and signed records with the relevant model, firmware or drawing revision.
A passing result for one configuration does not automatically cover a different voltage, optical assembly, interface, battery, mounting arrangement or software release. Define which differences require a document review, sample approval or repeated test.
Common specification mistakes
- Counting detector channels without defining the signal type
- Treating “RS-485” as a complete protocol specification
- Omitting detector fault and stale-data behavior
These errors usually appear when a quotation is based on a short product name instead of a system description. A clear schedule and acceptance record reduce rework during sample approval, production and commissioning.
Prepare the supplier enquiry
Send the project location, intended use, quantity, destination, applicable tender or standard, required interfaces, operating conditions and requested documents. Ask the supplier to identify confirmed items, options and exceptions in writing. For GAOQIAO catalogue options, start from the relevant product category and request the current drawing and data for the exact offered model.
Frequently asked questions
Can a dry-contact detector connect to every controller?
Only when the input voltage, current, isolation and expected contact behavior match. Confirm the wiring diagram for the exact controller revision.
Does a network detector replace field wiring?
It changes the interface but still requires addressing, timing, recovery and fault supervision to be specified.
What should be tested at acceptance?
Valid calls, minimum pulse, stuck input, lost link, recovery and event timing should be checked against the agreed I/O schedule.