Plant power project, a basic user requirement which is: when the firing system, the need to provide a recording time of each shot (instant SOE function), the time accuracy typically 1 millisecond, and then , determines the travel time based on these priorities, investigate the reason for the problem. To make travel times comparable, the time between the entire plant and even more plants needs to be synchronized. This brings us to today's topic: clock synchronization.

What is CIP Sync?

CIP synchronization in the clock synchronization extension of the CIP (Common Industrial Protocol), based on the IEEE-1588-2008 standard - precision clock synchronization protocol for network measurement and control system (referred to as PTP). CIP Sync is also a standard developed by the Open DeviceNet Vendor Association (ODVA) and is fully compliant with the IEEE 802.3 (Ethernet) standard.

IEEE 1588-2008 is a mechanism that allows all devices in a network system to be synchronized based on a common time with sub-subtle precision. With the help of hardware components, you can even get a precision of one billionth of a second. The CIP Synchronization (IEEE-1588 PTP) message has the highest level of transmission priority throughout the network system, which ensures the accuracy of the clock synchronization.

Why use the CIP sync protocol?
This is because using CIP synchronization can achieve the following advantages:
1. Compliance with the IEEE 802.3 standard, which means that a standard Ethernet switch using a common clock synchronization can be achieved accuracy of less than 1 millisecond. Network that supports IEEE 1588 V2 or IEEE 1588 switch V1 configuration, each network device can reach 100 100 nanosecond clock and delicate synchronization accuracy. IEEE 1588-enabled switches are fully compliant with IEEE 802.3 Ethernet.
2. Compatible with any standard Ethernet technology, such as various Ethernet topologies, such as star, ring, tree, etc. Better flexibility when the project is implemented.
3. In the configuration phase of the system, since the synchronization of the shorter clock, frame synchronization does not need to classify network, automatically propagates the used clock.
4. Simplify the structure of the system. Earlier systems to establish a synchronization network of the special synchronization clock, which is due to be taken to the original synchronization signal of the GPS clock, the format of the signal because of compatibility problems, is necessary and industrial networks, field bus separately. For example, use: Synch-link (see the figure below), or RS485 communication line connection. This will lead to increased spinning costs, the introduction of electromagnetic interference, and increased management and maintenance.

Because CIP synchronization is based on standard Ethernet, more and more factories and enterprises are using industrial Ethernet connections. Therefore, the existing Ethernet features can be fully utilized and the sync signal need not be connected separately.

Overview of CIP Synchronization

CIP synchronization can be performed on the EN2T Ethernet module of the Rockwell Automation ControlLogix platform. The client used feedback: "The default behavior of the protocol makes simple system installation and operation no longer having to worry about factory management." Because the EN2T configuration is very simple and easy, it has been highly recognized by users.

EN2T behaves like a normal clock on an Ethernet. ControlLogix or EN2T synergic can Logix clock backplane on the clock accuracy and CST PTP clock master clock system M or the most advanced GM.

The figure describes an Ethernet-based synchronization network CIP, EN2T CIP Ethernet module to support synchronization, M for the master clock, S for the slave clock. The Grand Master Clock here refers to the clock that is synchronized in a domain using the protocol as the final time source. The figure of the system with the most advanced clock function arbitration, the system clock can cure, a failure time clock will not stop the transfer or synchronize, the system can determine its own to find the best master clock (Best Master Clock) .

Hardware system supporting CIP synchronization

Controller: The ControlLogix controller has native support for CIP synchronization. It can be used as master and slave of the precise PTP watch and cooperative watch CST. There is no need to program a shared clock between controllers. Simply check the box on the controller configuration page and the alarm system will automatically extract the CIP sync signal.
The time is shared between the controllers, a controlador Logix acts as the master clock and the other Logix controllers act as slave clocks.

Ethernet Module: EN2T supports CIP synchronization. The basic functions are:

1 Status and configuration: CIP synchronization package.
2 CST object: read system time, coordinate system clock, system offset.
3 Time synchronization object: activate / deactivate, obtain / set the time, set the priority master clock, obtain the synchronization status, obtain the PTP master status of the current accurate clock and information.
4 Web page: PTP diagnosis

Switch: 1783-ETAP, supports transparent clock function. A transparent clock is a device that can measure the time in which a PTP event message passes through the device and sends the information to the clock that accepts the PTP event message.
Switches: STRATIX 8000 and 8300. Basic Functions:

1 Transparent Clock
2 Limit clock. A boundary clock is one that has multiple PTP precision protocol protocol ports in a domain and maintains a time-scale clock used in that domain. It can be used as a source of time, ie as master clock, but can also be synchronized with another clock, which is the slave clock.

Distributed I / O: ArmorBlock that supports CIP synchronization. The function is as follows:
1 +/- 100 microseconds of date and time record.
2 3-port switching, input, output and internal port.
3.16 SOE inputs, scheduled output for backup.
4.24VDC power supply.

Rack-mount SOE Module: 1756-IH16ISOE / -IB16ISOE, firmware version 2.7. Provides the latest technology and the best cost-effective SOE failure / first failure detection system. The basic functions are:
1 Support for integrated CIP synchronization.
2 Supports high-precision time recording with "real-time" values ​​from standard Ethernet time sources.
3 The structure of the SOE solution is very simple, eliminating the original sync cable, such as SyncLink. In multi-rack systems, GPS modules are also not required.
4 The module provides a new "x10 first in the first output mode".
5 In high-speed applications, playback of 10 event timestamps can be provided for each request packet interval RPI.
6 Response time increased by a factor of 10.
CIP sync time use case: first fault detection (SOE)

The safety system sensors on the defective machine sometimes intermittently emit a fault signal, which eventually leads to an interruption in production, which, in turn, causes the failure of other related machines. Conventional fault detection or alarm system can not determine the actual failure occurs when the failure sequence, and therefore can not find the root cause of downtime and the real reason for failure.
Failure to accurately stamp the input signal can very accurately analyze the failure of the first signal, thereby easily determining the cause of the initial failure of a mechanical stop.
The public time record provides the common time reference standard for interaction between the user of the alarm system login (time) and the time record (time stamp) of the alarm event.
The power industry requires clocks with less than 1 millisecond precision for analytical queries for the first infrastructure failure of large area distributed plants.

Example of typical plant solution 1

The figure above shows an application case with GPS clock and ControlLogix controller redundancy. The top two controllers are ControlLogix CPUs for hot backup. A GPS module is inserted into the third-floor rack to receive GPS satellites clock signals. Here, GPS is used as the highest level (GM) clock, and other EN2TR Ethernet modules in the system are used as the slave clock S. The EN2TR Ethernet module in each rack acts as the local master clock M. The L6X module , SOE and the ArmorBlock SOE module distributed in the rack act as slave clocks S through the CIP synchronization signal.

The ETAP switch in the figure supports CIP synchronization for NTP conversion of the network clock protocol so that you can connect the HMI and PC.

Typical solution for example of plant 2

FIG There is L6x from the real time external source TDA, and then this rack is transmitted to the Ethernet module EN2T, this GM system being the largest EN2T clock, using UCT / CST (synchronous CIP / PTP) other EN2T rack The timing signal is provided from the S clock. The EN2T in each rack provides the time for the SOE modules in the rack. Reach the goal of the entire system for a unified time.

Here are the instructions for the three clocks in the figure:

1 CST - synchronous clock. It is a backplane clock that starts working when the system is initially turned on. It acts as a master watch for the bac

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