Start with the operating requirement
A clock source must be paired with an offline policy, event timestamps and a testable recovery sequence. 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 |
|---|---|---|
| Time source | NTP server, GNSS/GPS, central command or local clock | Establishes the authoritative source |
| Time zone | UTC storage, local offset and daylight-saving rule | Prevents schedule and log ambiguity |
| Offline limit | Permitted drift and maximum loss-of-sync period | Defines when time quality becomes unacceptable |
| Correction method | Step, gradual adjustment or maintenance intervention | Avoids unexpected timing changes |
| Audit record | Last sync, source, offset, failure and recovery | Lets support distinguish time faults from control faults |
Use a controlled review sequence
- Time source: NTP server, GNSS/GPS, central command or local clock Establishes the authoritative source
- Time zone: UTC storage, local offset and daylight-saving rule Prevents schedule and log ambiguity
- Offline limit: Permitted drift and maximum loss-of-sync period Defines when time quality becomes unacceptable
- Correction method: Step, gradual adjustment or maintenance intervention Avoids unexpected timing changes
- Audit record: Last sync, source, offset, failure and recovery Lets support distinguish time faults from control faults
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
- Setting the clock without defining time zone
- Synchronizing logs but not controller schedules
- Correcting time without recording the offset and source
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
Is GPS always better than NTP?
No. Suitability depends on antenna view, network design, security and the required holdover performance.
Should controller events use local time?
A common approach is to store an unambiguous time base and display local time, but the project must define this consistently.
How is drift tested?
Disconnect the reference for an agreed period, compare the controller clock with a traceable reference, then verify resynchronization and logs.