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Precision Time Synchronizing Using GPS and SNTP Servers

Precision Time Synchronizing Using GPS and SNTP Servers

When precision synchronizing of time is required on your processes, automatically coordinate all of your activities using Moore Industries’ NCS NET Concentrator System time sync features.

In July 2015, a Simple Network Time Protocol (SNTP) server feature was introduced into the EMM Ethernet/MODBUS Interface Module of the NCS, the CPMS Cathodic Protection Monitoring System and the microNCS MODBUS RTU Master and Distributed I/O System models. Previously, any of these models could be synchronized to an external SNTP time server via an Ethernet link so that each NCS site has the precise Coordinated Universal Time (UTC). Now, these models can also become their own SNTP server to provide timing to one or several compatible SNTP devices including the EMM, CPMS and microNCS along with other instrumentation or PLCs.

The CPMS and microNCS also have a new GPS Time option with an internal GPS receiver providing precise UTC time. Remote sites with no ability to connect to an existing external SNTP service can now obtain the same time as other remote sites anywhere in the world. The remote site equipped with GPS Time also automatically becomes an SNTP server to serve instrumentation from other vendors and PLCs capable of using SNTP.

We now have two solutions to provide high accuracy time for process coordination activities without using expensive “time server” instruments – the SNTP connection available in the NCS family and the GPS Time option available in the CPMS and microNCS modules. This gives you a high accuracy time method regardless of the availability of an Ethernet connection.

With the NCS family, configuration of time requires simple connection of an Ethernet cable and activating the feature via a webpage configuration screen. This clock runs continuously – even when the NCS unit is powered down. Configure the NCS’s clock using one of the following methods to best meet your precise timing application:

  • Utilizing the configuration webpages, select “Workstation Time” to set the internal clock to the time of the host computer (such as a laptop). The internal crystal oscillator clock is set and then maintains this time.
  • Select “Manually” to set a time other than the local time.
  • Select “Use Time Server” along with entering the Ethernet SNTP at your local facility, one external to your plant, or the IP address of another applicable NCS family unit. This clock will be accurate to the SNTP server clock. As the SNTP clock updates periodically, so will the NCS’ internal clock
  • Select “GPS” (requires the GPS Time option on the CPMS or mNCS). The unit will now be synchronized with the GPS clock.

Should the signal be temporarily lost from the SNTP server (such as a temporary loss of Ethernet connection) or the GPS (such as having fewer than four satellites locked), then the NCS’ internal clock automatically maintains time until the SNTP server or GPS service is restored.

There are several applications where these features are extremely useful:

Cathodic Pipeline and Tank Protection

A large pipeline and storage tank complex may require simultaneous shutdown of several cathodic systems at the same time to minimize contamination of the “reference signal” should one of the nearby rectifiers continue to operate. Using the CPMS’s internal clock to know when to perform shutdown and readings, this can be accomplished with the cathodic system unattended. Data is collected using the data logger and extracted remotely at a convenient time later. This eliminates the need for human intervention to synchronize the exact time of a few to hundreds of cathodic protection sites.

Transportation Switch Logging

This requires the precise timing when opening gates, transitioning vehicles and performing ID recognition. Using the GPS and SNTP features provides accurate time stamping of all process activities worldwide.

Transportation

Vehicle, trailer, pallet and other transportation systems stay synchronized when the GPS Time feature is activated. No additional time corrections are required for the internal time bases of the individual portable sites. Precise latitude, longitude or altitude data is available in addition to time. Contact Moore Industries for technical details.

Enterprise Timing

Coordinate the precise timing of two or more independent network activities such as power grid transfers and inter-company pipeline transfers in which the network of one site is not permitted to be physically linked to another site for reasons such as network security. Independent GPS at each network site assures precise time coordination for transfers between facilities.

Notes:

  • Access to an external SNTP server requires an Ethernet connection to the outside world. Make sure these network connections aren’t blocked by the security firewalls of your IT department.
  • The GPS feature requires an external antenna that can “see” the orbiting GPS satellites without obstructions (such as trees, buildings or ceilings). A building’s walls and ceilings will typically block the GPS RF signal from the satellites so the external GPS antenna may need to be relocated. There is no security firewall involved in GPS satellite protection.
  • For process control, the precise timing for a small to large system is considered to be timing precision of approximately 0.1 seconds. This includes automatic correction of time delays of wireless links, LAN repeaters and more without human intervention.
Published: July 29, 2015
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