Power-Grade Industrial Grandmaster Clock

  • High precision GNSS module
  • Stratum 1 NTP Server, with Optional PTP hardware-support
  • PTP Version supports IEEE61850-9-3 and IEEEC37.238 Power Profiles
  • Holdover <30 ns/second time-drift when disconnected from GNSS
  • IEC62439-3 Clause 5 Parallel Redundancy Protocol (PRP)
  • Industrial fanless design for -40~85°C operation; IEC61850-3 protection
  • Flexible modular configuration; 2 dedicated Output Module slots
  • 2 x 10/100/1000 Mbps RJ45 and 2 x 100/1000 Mbps Combo SFP slots
  • Embedded NTP/SNTP client and NTP server
  • Support for Legacy Protocols: IRIG-B, BJT, BCD, ST, ST with checksum
  • Redundant power input; low-Voltage DC or high-Voltage AC/D

A Powerful base for NTP and PTP
The NTS7500 1U 19’’ Rack-mount Modular NTP Server with additional Grandmaster Clock feature is a high-powered rugged device that offers good precision and reliability. Suitable for almost any environment and complying with the harshest Industrial EMC conditions, ATOP’s device satisfies all  ndustry requirements for Industrial-grade networking timing applications. Its modular architecture provides power-input redundancy and up to 16 different outputs for legacy time Protocols – such as IRIG-B, BCD, ST, ST with checksum.


Stratum 1 NTP Server: NTS7500 embeds a high precision, multi-system GNSS module that supports GPS, GLONASS, BEIDOU and GALILEO GNSS Systems for redundancy. When disconnected from a GNSS time source, its integrated TCXO Oscillator, ensures time drift (1PPS output) does not exceed 30 ppb matching and exceeding the requirements for Power Substations. NTS7500 supports NTPv1/v2/v3/v4 Server and NTP/SNTP Client.


Optional PTP Standard Support: NTS7500 supports Layer-2 and Layer-3 over IPv4 transport; VLAN Tagging; and Multicast, Unicast and Unicast Negotiation in both End-to-End and Peer-to-Peer delay calculation modes. NTS7500 fully supports IEEE C37.238-2017 and IEEE/IEC 61850-9-3 – 2016 Power Profiles.



Industrial and Substation Hardware : Designed to satisfy EMC requirements for Substation-Grade equipment, NTS7500 has a minimum EMC Level 4 rating and is designed to function between -40°C and 85°C with passive cooling only, allowing it to avoid the risk of having moving parts breakdown from constant operations. Also, its powerful CPU supports up to 2,000 packets per second, allowing endless applications and a large number of slaves to be supported simultaneously. Redundancy through IEC62439-3 Clause 5 PRP.



Proven design: No standardized testing procedure for PTP devices exists. So ATOP tests its products yearly in ISPCS Plugfests to demonstrate their reliability. NTS7500 was successfully tested in Stockholm 2016, Monterey 2017, Geneva 2018 and Portland 2019. More information available on www.ispcs.org.




IEEE1588v2 Precision Time Protocol
PTP is the only protocol that allows network time synchronization in the nanosecond-range. Current networking protocols nor legacy protocols allow such a timestamp resolution. IEEE1588-2008 (v2) derives from an earlier version issued by IEEE in 2002 that is not backward compatible. Being so exact about timestamp resolution and timekeeping, IEEE1588v2 timestamps are required to be hardware-generated, since no software could keep up with some stringent requirements, no matter the processing power. PTP is a hierarchical protocol, in which Grandmaster Clocks are directly synchronized with reference clocks such as GNSS or Atomic Clocks, with subsequent layers reaching slaves devices. PTP packets are timestamped with a nanosecond resolution.

To achieve such accuracy, PTP works best on Local Area Networks without passing through the internet: latencies and paths would introduce variables latencies that couldn’t be accommodated for in the accumulated delay calculations. PTP packets should always travel the same path during each synchronization phase to preserve such high accuracy. PTP is designed to work on Ethernet transport, Layer-2 (Data-link Layer) or Layer-3 IPv4. And there are two methods to calculate link delay: in End-to-End mode, link delay is calculated from the source of the PTP packet until its destination, while in Peer-to-Peer mode, link delay is calculated as between each network node. In addition, PTP is Internet-capable, with IPv4 in unicast and unicast negotiation modes.



Application example
This network diagram shows the use of ATOP’s NTS7500 in a substation environment. The GMC is usually located in the office building adjacent to the substation. On one side, it is connected to the GNSS Antenna, with the other side being the Substation backbone connection. Every switch connected to the Grandmaster should be able to handle all Precision time Protocols by hardware, in order not to affect the synchronization quality. Packets are delivered downstream through Boundary or Transparent clocks, where they’ll reach PTP slaves – such as substation IEDs.

StandardsIEEE 802.3 10BaseT
IEEE 802.3u 100BaseT(X)
IEEE 802.3ab for 1000BaseT(X)
IEEE 802.3u for 100Base-FX
IEEE 802.3z for 1000Base-X
ITU-T G.8261 Synchronous Ethernet (NTS7500-CPU-PTP only)
Ports2x 10/100/1000BASE-T(X) RJ45 combo ports
2x 100/1000 Base-X SFP Slots combo ports
LAN ModeDual Subnet or PRP (Parallel Redundancy Protocol)
GNSS/Clock Specifications  
GNSS Input ports1x GNSS Input; 1 x BNC (F)
GNSS Module specific InformationGNSS Supported
GNSS Module latency
Leap Second
<15ns GNSS/PPS output latency
1PPS Output1x PPS Output, Square Wave, 1000ms pulse width, coaxial BNC (F) connector
10MHz Reference Output1x 10MHz Reference Output, Sine Wave, coaxial BNC (F) connector
OscillatorEntry-level OCXO
ProtocolsNetwork SynchronizationRFC 868 (Time Protocol)
RFC 867 (Daytime Protocol)
RFC 1119 (NTPv2) Server/ Client
RFC 1305 (NTPv3) Server/ Client
RFC 5905 (NTPv4) Server/ Client
RFC 1769 (SNTPv3) Server/ Client
RFC 2030 (SNTPv4) Server/ Client
RedundancyIEC62439-3 clause 5 Parallel Redundancy
Protocol (PRP)
Configuration and
RFC 1157 (SNMPv1)
RFC 1901-1908 (SNMPv2c)
RFC 3411-3418 (SNMPv3)
RFC 1157, RFC 1213, RFC 1215, RFC 1493, RFC 1643, RFC 1757, RFC 2011,
RFC 2012, RFC 2013, RFC 2233, RFC 2571, RFC 2742, RFC 2819, RFC 2863,
RFC 3411, RFC 3412, RFC 3413, RFC 3414, RFC 3415, RFC 2674
Precision Time Protocol
NTS7500-CPU-PTP only
Operation ModeGrandmaster Clock (NTS7500-CPU-PTP only)
Supported PTP modesL2 : Multicast
L2 VLAN Tagging: Supported
L3 IPv4: Multicast, Unicast, Unicast Negotiation
One or two-step clock modes supported
End-to-End or Peer-to-Peer supported
Holdover Performance< 30 ns/second drift when not locked to GNSS,
after 24 hours operation
total ~1 us/24 hrs drift after locked to GNSS
after 24 hours (0.052 us/hr)
PPS Stability70 ns when locked to GNSS
PTP Precision+/- 50 ns error, as per test with third party slave
Supported PTP ProfilesPTP default profile, VLAN support
C37.238 -2017 Power Profile
IEC/ IEEE61850-9-3 Power Profile(2016)
User can modify the detailed PTP settings
Maximum number of
NTS7500-CPU-PTP can support maximum
2,000 PTPpps (PTP packets per seconds).
Physical Characteristics  
HousingSPCC IP30 Metal Housing
Dimension (core unit) (W x H x D)440 x 44 x 340 mm (not including screws and rack-mount kit)
Weight (core unit)5.6 Kg (not including module but module cover only)
Installation1U Rack-mount, Rack-mount kit included
Power inputs (core unit)Dedicated 2 Power module slots (for redundancy)
Output modules (core unit)Dedicated 2 Output module slots (IRIG-B and Serial freely exchangeable)
Environmental Limits 
Operating Temperature-40°C~85°C (-40°F~185°F) / LCM display maximum 0~70 °C
Storage Temperature-40°C~85°C (-40°F~185°F) / LCM display maximum -30~80 °C
Ambient Relative Humidity5%~95% (Non-condensing)
Power Modules
Model nameNTS7X00-AC Power ModuleNTS7X00-DC Power Module
Input Voltage110-240 AC / 120~240 VDC20-60 VDC
Input Current (Max)110-240 VAC, 0.2 A Max
120-240 VDC, 0.2 A Max
20-60 VDC , 0.8 A Max
Input Power (Max)Approx. 20W MaxApprox. 20W Max
Relay output1 Relay (normal open)1 Relay (normal open)
Physical Characteristics
Dimension (W x H x D)
84.5 x 39.5 x 204.8 mm
500 g
Cold plug-in (screws provided)
84.5 x 39.5 x 190.5 mm
200 g
Cold plug-in (screws provided)
IRIG-B and Serial Output Expansion Modules
Model nameNTS7X00-S1
Connector2 x 12-pin terminal block
Ports8 x RS-485
Protocols supportedIRIG-B, BCD BJT,
ST, ST with Checksum
ConfigurationSoftware-selectable by port,
through web interface
Physical Characteristics
Dimension (W x H x D)
119.5 x 39.5 x 190.5 mm
350 g
Cold plug-in (screws provided)
SafetyCB(IEC)/EN 60950-1 & CB(IEC)/EN 62368-1
EMCFCC Part 15, Subpart B, Class A, EN 55032:2012, EN61000-6-4, EN 61000-3-2,
EN 61000-3-3, EN 55024, EN 55035, EN61000-6-2
IEC 61000-4-2_2008ESDContact Discharge
Air Discharge
IEC 61000-4-3_2010RSEnclosure Port
10(V/m) , 80-1000MHz
3(V/m), 1.4~6GHz
IEC 61000-4-4_2012EFTAC Power Port
DC Power Port
Signal Port
±2.0KV @ 5.0KHz
±1.0KV@ 5.0KHz
±1.0KV @ 5.0KHz
IEC 61000-4-5_2017SurgeAC Power Port
AC Power Port
DC Power Port
DC Power Port
Signal Port
Line-to Line±1KV
Line-to Earth±2KV
Line-to Line±0.5KV
Line-to Earth±1KV
Line-to Earth±1.0KV
Line-to Earth±4.0KV
IEC 61000-4-6_2013CSAC Power Port
DC Power Port
Signal Port
10V, 150KHz~80MHz, 80%AM
10V, 150KHz~80MHz, 80%AM
10V, 150KHz~80MHz, 80%AM
IEC 61000-4-8_2009PFMFEnclosure100A/m continuous, 1000A/m (3s)4
IEC 61000-4-11_2017DIPAC Power Port30% Reduction (Voltage Dips) : 25/30 Cycle
60% Reduction (Voltage Dips) : 10/12 Cycle
100% Reduction (Voltage Dips) : 1 Cycle
100% Reduction (Voltage Interruption) : 250/300 Cycle
IEC 61000-4-16Main FrequencyDC input or output
Signal Port
Telecommunication Port
30 V continuous / 300V 14
IEC 61000-4-17RippleDC input or output15% of unit (10% Level 3)4
IEC 61000-4-18Damped OscillatoryAC Power Port
DC Power Port
2.5KV common,
1KV differential mode @ 1MHz
IEC 61000-4-18Damped OscillatorySignal Port
Telecommunication Port
2.5KV common,
2.5KV differential mode @ 1MHz
ShockMIL-STD-810G Method 516.5
DropMIL-STD-810F Method 516.5
VibrationMIL-STD-810F Method 514.5 C-1 & C-2
Warranty5 Years
MTBF9.20 Years
NTS7500-CPU-PTP1P1NTS75000001GIEEE1588v2 PTP Grandmaster and NTP Server core
NTS7X00 SERIAL MODULE1P1NTS7X000001GIRIG-B and Serial Output module for NTS7500 - 16-pin Terminal Block
NTS7X00-AC POWER MODULE1P1NTS7X000002GT;110~240 VAC;120-240 VDC,0.2A;G
NTS7X00-DC POWER MODULE1P1NTS7X000003GT;24-60 VDC;0.8A Max;G
Model namePart NumberDescription
SDR-75-2450500752240001GDIN RAIL POWER SUPPLY / T;AC 88~264V to 24VDC 3.2A;75W
AXFD-1314-0523522AXFD1314001GSFP Transceiver;155Mbps, Multi-mode;1310nm;2km;-40~85, DDMI
AXFD-1314-0553522AXFD1314011GSFP Transceiver;155Mbps, Single-mode;1310nm;30km;-40~85, DDMI
AXGD-5854-0513522AXGD5854001GSFP Transceiver, 1250Mbps, 850nmVCSEL, Multi-mode, 550m, 3.3V, -20~85°C
AXGD-1354-0523522AXGD1354001GSFP Transceiver, 1250Mbps, 850nm, Multi-mode, 550m, 3.3V, -40~85°C, DDMI
AXGD-1354-0533522AXGD1354011GSFP Transceiver, 1250Mbps, 1310nm, Multi-mode, 2km, 3.3V, -40~85°C, DDMI
AXGD-3354-0593522AXGD3354001GSFP Transceiver, 1250Mbps, 1310nm, Single-mode, 40km, 3.3V, -40~85°C, DDMI
High-Accuracy GNSS Active Antenna59901591GOutdoor Antenna - GL-111
RHG9528-BSSee datasheetIEC61850-3 Rack-mount Modular Managed Switch & 1588v2 BC/TC
EHG9508/12See datasheetIEC61850-3 DIN-Rail Managed Switch & 1588v2 TC


Version Name Time Size Download
v5.60 Management Utility for Windows 2021-01-18 23.65 MB
v5.20 Management Utility for Windows 2019-09-09 16.21 MB


Version Name Time Size Download
v6.18 NTS7500-PTP_Firmware 2021-02-22 11.55 MB
v6.15 NTS7500-PTP_Firmware 2020-10-07 11.43 MB


Version Name Time Size Download
v1.6 Datasheet EN 2021-09-13 831.61 KB
v1.4 Datasheet EN 2021-03-10 1.02 MB
v1.3 Datasheet EN 2020-12-22 1.02 MB
v1.2 Datasheet EN 2020-08-25 1.02 MB
v1.1 Datasheet EN 2020-08-18 1.02 MB
v1.0 Datasheet EN 2020-07-24 1.02 MB
v0.9 Datasheet EN 2020-06-17 1.02 MB
v0.8 Datasheet EN 2020-04-20 1.02 MB
v0.7 Datasheet EN 2020-03-12 1.02 MB
v0.6 Datasheet EN 2020-02-04 1.02 MB
v0.5 Datasheet EN 2019-12-16 908.43 KB
v0.4 Datasheet EN 2019-12-12 905.66 KB
v0.3 Datasheet EN 2019-10-31 617.09 KB
v0.2 Datasheet EN 2019-09-09 692.75 KB


Version Name Time Size Download
v0.7 NTS7X00 User Manual 2021-06-07 899.72 KB
v0.5 NTS7X00 User Manual 2020-07-24 1.37 MB
v0.4 NTS7X00 User Manual 2019-09-09 1.46 MB

Hardware Installation Guide

Version Name Time Size Download
v1.0 NTS7500 Series Hardware Installation Guide 2019-11-05 3.89 MB

Test reports

Version Name Time Size Download
NTS7500 Declarations of Conformity 2023-03-15 306.89 KB
v1.0 NTS7500 Certification CE_FCC 2020-09-30 9.1 MB
v1.0 NTS7500 Certification Safety (CB) 2020-09-30 1.19 MB

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