# Industrial NTP Time Server — Product Specification (Shipping)

| Item | Content |
|------|---------|
| **Audience** | Agents / end customers / tender package |
| **Document title** | Product Specification (Shipping) |
| **Doc No.** | `DOC-TS1231-DS-EN-011` |
| **Model** | **SY-1231-BG-T-S** / **SY-1231-GN-T-S** |
| **Document version** | 1.4 (this respin: design reply ≈1800 req/s, aligned with V4.9.0-b162) |
| **Firmware** | V4.9.0 (see device label / Web Dashboard Firmware & Build) |
| **Related documents** | User Guide (bid-sanitized); Industrial Interface Protocol (annex) |
| **One-pager** | Selection Sheet (Reference · Policy · Capacity) |

---

## 1. Overview

GNSS-disciplined LAN **NTP Stratum 1** time server providing Ethernet NTP, RS-485 Modbus absolute time, TTL **1PPS** (GNSS edge via 硬件缓冲), and a four-pin **PPM pulse**. For industrial, security, office, and auxiliary metrology timing. **This respin has no IRIG.**

| Item | Specification |
|------|----------------|
| Commercial model | **SY-1231-BG-T-S** / **SY-1231-GN-T-S** |
| Constellation code | **BG** = BeiDou + GPS (UI may show `BD+GPS`); **GN** = GPS + GLONASS. Follow the nameplate / Web |
| Oscillator / Power | **T** = TCXO; **S** = single supply |
| Timing protocol | NTP v3/v4 (UDP **123**) |
| Time reference | GNSS 1PPS + TCXO discipline; industrial RTC holdover (temperature-compensated) |
| Management | Web (HTTP Basic Auth) + front-panel LCD; **SNMP read-only** (UDP **161**, SNMPv2c) |
| Identity | Factory SETID (Web / LCD: `SN:`) |

---

## 2. Electrical & Environment (summary)

| Item | Specification |
|------|----------------|
| Power | **Single path `-S`**. Two inlets; **use only one at a time**: (1) **AC 220 V** IEC-style inlet (isolated step-down); (2) **DC-IN** + external adapter, **12–24 V DC** (see nameplate/adapter). Do not feed AC and DC together. Export: plug/adapter per order. Not dual-redundant (`-D`) |
| Ethernet | **1×** RJ45, 10/100M (single port; not dual-port redundancy) |
| Operating temperature | Per hardware datasheet / nameplate |
| Default IP | **192.168.1.123** / 255.255.255.0 / gateway 192.168.1.1 |

---

## 3. Interfaces

| Interface | Function | Notes |
|-----------|----------|--------|
| RJ45 | NTP + Web | Same IP/MAC; not a second independent port |
| RS-485 | Modbus RTU slave | Absolute UTC time registers (incl. ms) |
| 1PPS OUT | TTL pulse-per-second | 硬件缓冲 GNSS-edge fan-out (3.3 V); not MCU-driven |
| PULSE | PPM | 4-pin Pin4; 200 ms at UTC minute after LOCK (5 V via level shifter) |
| GNSS antenna | Fix + 1PPS | Outdoor antenna as installed |
| Front panel | LCD + single key | Ops / status display |

---

## 4. Timing Accuracy (by channel)

Metrics of different interfaces **must not be mixed**.

| Channel | Typical capability (after LOCK) | Use |
|---------|----------------------------------|-----|
| Internal / GNSS 1PPS reference | Short-term typically ≤ **10 ns RMS** (see validation report) | Factory / acceptance reference |
| TTL 1PPS OUT | GNSS second edge via hardware buffer | Hardware second-edge sync |
| RS-485 Modbus | **1 ms** resolution | PLC / SCADA absolute time |
| Ethernet NTP | **Lab clause:** LOCK + low LAN RTT → client offset **can reach ms class** (see report); **no** arbitrary-field guarantee | PCs / servers / switches |
| Holdover | Degrades toward ppm with unlock time | Short GNSS outages |

> **Important:** “GNSS 1PPS 10 ns RMS” is **not** “NTP client 10 ns” or “nanosecond Modbus timing.”

---

## 5. NTP Service

| Item | Specification |
|------|----------------|
| Mode | NTP server (RFC 5905 subset) |
| After LOCK | Typically **Stratum 1** |
| Warm-up / policy window | May reply Stratum 2 per Web serve policy (factory default: lock-based serve) |
| **NTP performance** | Overload protect ≤ **2048** req/s; **design reply capacity ≈ **1800** req/s (16 sources)**; sustainable **\(R\)** same as design reply (do **not** copy 10 k-class appliances) |
| **Planning cap** | **60** (sales/SNMP; **≠** sync density) |
| **Client count** | \(N \le \min(60,\lfloor\eta\cdot R/f_{\mathrm{poll}}\rfloor)\), \(\eta\) 0.5–0.7; customer computes from poll rate |
| Per source IP | ≤ **8** replies/s |
| Global replies | **Adaptive** rate limit; further derated during large Web exports |
| ACL | Optional NTP source IP allow-list (Web) |

**Not included:** **IRIG-B**, **OCXO**, PTP/IEEE 1588 stack (**no** third-party PTP license pack), NTS, dual-port failover, IPv6, NTP broadcast/multicast server, **HTTPS**, SNMPv3 / SNMP write. Oscillator class is **-T-** (**TCXO**).

---

## 6. RS-485 Modbus RTU

| Item | Specification |
|------|----------------|
| Link | **9600 8N1** |
| Slave ID | **0x01** |
| Function codes | Read **0x03 / 0x04** (write only for factory use; see protocol annex) |
| Clock registers | UTC Y/M/D/h/m/s/**ms** |
| Poll rate | Recommend ≥ **1 Hz** |

Full register map: Industrial Interface Protocol annex.

---

## 7. 1PPS & PULSE (summary)

| Item | 1PPS OUT | PULSE (4-pin Pin4) |
|------|----------|-------------------|
| Drive | Hardware-buffered 3.3 V TTL | Level-shifted 5 V TTL |
| Role | Metrology second edge | UTC **minute PPM** (default 200 ms, LOCK only) |
| Absolute time | Pulse = GNSS second boundary | Minute boundary; calendar via Modbus/NTP |
| Not | not a software square-wave on this jack | Impersonating 1PPS; IRIG |
| Accept | Scope on 1PPS jack (1PPS 输出座) | Scope Pin4: ~200 ms at UTC minute after LOCK; mute if unlocked |

---

## 8. Management & Logs

| Item | Specification |
|------|----------------|
| Web | Dashboard / Network; Basic Auth. Neutral masthead: footnote **TemporaSync™**, subject **SY-1231**, role **NTP Time Server · Stratum 1**; version only in Firmware / Build |
| SNMP | **Read-only** SNMPv2c, UDP **161**; MIB-II system + device status; **no** Set / SNMPv3 / Trap; enterprise OID per shipping note |
| Syslog | **Optional** UDP edge push (default OFF); same dictionary as `event_log`; Web Network configures target IP:514 |
| Event log | `event_log.csv` (`/flog`), ring ~**2048** entries; default export ~**latest 1024**; Dashboard → Diagnostics → Export |
| 24 h quality | `quality_24h.csv` (`/stats24`); hourly buckets; `samples=0` = no GNSS-disciplined samples that hour |
| Front panel | Four pages: patrol / decide / diagnose / asset |

---

## 9. Ordering & Traceability

Record on the shipping sheet:

```text
Model: SY-1231-BG-T-S or SY-1231-GN-T-S
SETID: _______________
Firmware / Build: _______________
Production test: PASS / FAIL
```

---

## 10. Related Documents

| Document | Content |
|----------|---------|
| Reference · Serve Policy · Capacity (One Page) | Selection Sheet (Reference · Policy · Capacity) |
| User Guide | Power-up, LCD, Web, clients, FAQ |
| Industrial Interface Protocol | Modbus map, PULSE PPM, 1PPS (hardware fan-out), integration checklist |
| This specification | Contract / selection boundaries |

*This document is a shipping/contract summary. Implementation details follow the annex and the shipped firmware.*