Description
Time-of-day synchronization is supported by all three major product families in the SIMATIC range: SIMATIC S7, SIMATIC S5 and PC. This synchronization can be done both via Industrial Ethernet and via PROFIBUS and MPI. There are two modes available for time-of-day synchronization via Industrial Ethernet:

• SIMATIC mode
• NTP mode (see Entry ID: 17990844)

Time-of-day synchronization via Industrial Ethernet with the SIMATIC mode
This mode is usually used in process automation in conjunction with ISO transport services and is precise to +/- 10ms between the communications processor (CP) and the synchronized CPU with a resolution of +/- 1ms.
Since SIMATIC mode is based on SNAP services (i.e. ISO Layer 2 service) and works with MAC addresses, it can only be used with local Ethernet networks. This mode does not work with IP networks via IP routers, i.e. with configured IP subnets.

Important
CP343-1 IT 6GK7343-1GX20-0XE0:
When using the "Set CPU time", you must select the MPI address 2 for the CPU. This has been cleared with firmware update V1.1 (see Entry ID: 21070809).

Fig. 01

Time-of-day synchronization for the S7-300 station is configured in the Hardware Configuration. In the Properties dialog of the CPU, you select the "Diagnostics/Clock" tab and then select the synchronization mode. You can configure the S7-300 CPUs as time master (time-of-day transmitter) or time slave (time-of-day receiver). Set whether synchronization is to be in the CPU (synchronization in the PLC) or via MPI (synchronization on MPI). Synchronization in the PLC includes the CPs. You can select a time interval of between 1 second and 24 hours for the synchronization.

Configuring time-of-day synchronization for the S7-300 CPU
There is only need to configure time-of-day synchronization for the S7-300 CPU if you are using one of the following Industrial Ethernet CPs:
 

No.	SIMATIC S7 300	MLFB	Firmware
1	CP343-1	6GK7 343-1EX30-0XE0	V2.2 onwards
2	CP343-1 Adv	6GK7 343-1GX30-0XE0	V1.0 onwards
3	CP343-1 Lean	6GK7 343-1CX10-0XE0	V2.2 onwards

If you are using one of the above-mentioned Industrial Ethernet CPs, then you must make settings in the Properties dialog of the CPU. The settings depend on the configuration of the communication bus in the backplane bus of the CPU.

• The communication bus is physically "wired through" to the MPI interface on the CPU. This setup is found in "small" CPUs, i.e. from the CPU 312 up to and including the CPU 315-2 DP and the C7 devices. In this case, in the Properties dialog of the CPU you select the "Diagnostics/Clock" tab and set "As slave" or "As master" for the synchronization mode on the MPI.

Fig. 02

Fig. 03

• The communication bus is not physically "wired through" to the MPI interface on the CPU, i.e. the MPI interface and the communication bus are separate. This bus setup is found in "large" CPUs, i.e. from the CPU 315-2 PN/DP up to and including the CPU319-3 PN/DP. In this case, in the Properties dialog of the CPU you select the "Diagnostics/Clock" tab and set "As slave" or "As master" for the synchronization mode in the PLC.

Fig. 04

Fig. 05

Precise to +/- 10ms.

If the S7-300 is configured as time master, then the time-of-day messages of the CPU are forwarded via the Industrial Ethernet CP to the time slaves in the Industrial Ethernet subnetwork.

If the S7-300 is configured as time slave, then the time-of-day messages of the time master are forwarded via the Industrial Ethernet CP to the CPU.

You configure forwarding of time-of-day messages via the Industrial Ethernet CP in the Hardware Configuration of the S7-300 station. In the Hardware Configuration of the S7-300 station, you open the Properties dialog of the Industrial Ethernet CP and select the "Time-of-Day Synchronization" tab. Enable the "Forward time of day" function. Click "OK" to close the dialog. 

Fig. 06

Note
More information on time-of-day synchronization via Industrial Ethernet

• with the S7-400 is available in Entry ID: 18130164.
• with the PC station is available in Entry ID: 44045424
• with SIMATIC S5 is available in the manual "SINEC CP1430", section 6.6 "Setting and Reading the Time" in Entry ID: 12586144.

Description:
In an automation network of multiple SIMATIC stations you have the option of synchronizing the clocks of all the CPUs. For this, you parameterize the clock of one CPU as the "master clock" and set the interval at which synchronization is to take place. You parameterize the CPUs to be synchronized as "slave clocks". You set the parameters via the CPU properties.

Fig. 01: Setting synchronization on a CPU 315-2DP as example

You can set synchronization separately:

• in the PLC (i.e. internal)
• on an MPI (i.e. external)
• on an MFI (i.e. external via 2nd interface)

Detailed information on time synchronization is available from the following sources:

• For S7-300 CPUs - the manual "S7-300 CPU 31xC and CPU 31x, Technical Data", "Interfaces" chapter, in Entry ID:12996906
• For S7-400 CPUs - the manual "Automation System S7-400 CPU Specifications", "Time Synchronization" chapter, in Entry ID:23904550
• For CP 343-1 - the device manual "Part B CP 343-1", "Time Synchronization" chapter, in Entry ID:24485272
• For CP 443-1 - the device manual "Part B CP 443-1", "Time Synchronization" chapter, in Entry ID:27013386

Note:

• A description of time synchronization via Industrial Ethernet with the SIMATIC procedure is available in Entry ID:18130164.
• A description of time synchronization via PROFIBUS in the SIMATIC environment is available in Entry ID:17544115.
• A description of time synchronization via MPI subnetwork in the SIMATIC environment is available in Entry ID:17521938.

Description
The Siclock system is a system that can be parameterized, and is modular and optimally adjusted for time synchronization of plants of all sizes.

The following home page provides manuals for the Siclock system and information on contacts for technical support and system consultants/sales:
http://www.siemens.com/siclock 

Furthermore, our products are in the Siemens IK PI Catalog, chapter 2 "PROFINET/Industrial Ethernet" at:
http://www.automation.siemens.com/net/html_76/support/printkatalog.htm
as well as in the SIEMENS PMD.

The Siclock hotline team is ready to answer all your questions on the topic of Siclock:

Product Lifecycle Manager (PLM)
Bernd Müller
Weissacher Straße 11
70499 Stuttgart
Tel.: +49 711 137-6101
Fax.: +49 711 137-6090
E-mail: bernd.mb.mueller@siemens.com

Siclock Hotline
Mon.-Fri. 8am to 4pm
Tel.: +49 (9131) 7-28866
Fax: +49 (9131) 18-80604
E-mail: siclock@siemens.com

Please get in touch with your nearest Siemens subsidiary or regional company for ordering.

Introduction
The NTP (network time protocol) is a general mode for synchronizing system clocks in local and global networks. The NTP mode differs fundamentally from most other protocols. NTP synchronizes not just all sorts of clocks with each other but also establishes a hierarchy of NTP time servers and NTP clients. A hierarchy level is called a "stratum", whereby "stratum 1" is the highest level. Time servers of this level synchronize themselves to a reference time source; these can be radio clocks, GPS receivers or modem time services. Stratum One Time Servers make their time available to multiple NTP clients in the network, which are designated as "stratum 2".

In the NTP mode, the CP transmits time-of-day queries (in client mode) to the NTP server in the subnet (LAN) at regular intervals. Taking the responses from the servers as a basis, the most reliable and most precise time-of-day is ascertained, and the time-of-day of the station is synchronized. The advantage of this mode is that it enables the time-of-day to be synchronized over and beyond subnet limits. The precision depends on the quality of the NTP server used.

SIMATIC S7-300 components with the time synchronization function using the NTP.
 

SIMATIC S7-300	Order number	Firmware
CPU314C-2 PN/DP	6ES7314-6EH04-0AB0	V3.3
CPU315-2 PN/DP	6ES7315-2EH13-0AB0	V2.5
CPU315-2 PN/DP	6ES7315-2EH14-0AB0	V3.1
CPU315F-2 PN/DP	6ES7315-2FH13-0AB0	V2.5
CPU315F-2 PN/DP	6ES7315-2FJ14-0AB0	V3.1
CPU317-2 PN/DP	6ES7317-2EK13-0AB0	V2.5
CPU317-2 PN/DP	6ES7317-2EK14-0AB0	V3.1
CPU317F-2 PN/DP	6ES7317-2FK13-0AB0	V2.5
CPU317F-2 PN/DP	6ES7317-2FK14-0AB0	V3.1
CPU319-3 PN/DP	6ES7318-3EL00-0AB0	V2.4
CPU319-3 PN/DP	6ES7318-3EL01-0AB0	V3.2
CPU319F-3 PN/DP	6ES7318-3FL00-0AB0	V2.5
CPU319F-3 PN/DP	6ES7318-3FL01-0AB0	V3.2
CP343-1	6GK7343-1EX20-0XE01)	V1.1
CP343-1	6GK7343-1EX21-0XE0	V1.0
CP343-1	6GK7343-1EX30-0XE0	V2.0
CP 343-1  IT	6GK7343-1GX11-0XE01)	V2.0
CP343-1 IT	6GK7343-1GX20-0XE0	V1.0
CP343-1 Adv	6GK7343-1GX21-0XE0	V1.0
CP343-1 Adv	6GK7343-1GX30-0XE0	V1.0
CP343-1 Adv	6GK7343-1GX31-0XE0	V3.0
CP343-1 Lean	6GK7343-1CX00-0XE01)	V1.0
CP343-1 Lean	6GK7343-1CX10-0XE0	V1.0

Table 01
¹⁾ Only the time-of-day of the internal CP diagnostics buffer is synchronized by means of the NTP.

ET 200 CPUs with the time synchronization function by means of the NTP.
 

ET 200 CPU	Order number	Firmware
IM151-8 PN/DP CPU	6ES7151-8AB00-0AB0	V2.7
IM151-8 PN/DP CPU	6ES7151-8AB01-0AB0	V3.2
IM151-8F PN/DP CPU	6ES7151-8FB00-0AB0	V2.7
IM151-8F PN/DP CPU	6ES7151-8FB01-0AB0	V3.2
IM154-8 PN/DP CPU	6ES7154-8AB00-0AB0	V2.5
IM154-8 PN/DP CPU	6ES7154-8AB01-0AB0	V3.2
IM154-8F PN/DP CPU	6ES7154-8FB01-0AB0	V3.2
IM154-8FX PN/DP CPU	6ES7154-8FX01-0AB0	V3.2

Table 02

SIMATIC S7-400 components with the time synchronization function using the NTP.
 

SIMATIC S7-400	Order number	Firmware
CPU412-2 PN	6ES7412-2EK06-0AB0	V6.0
CPU412-5H PN/DP	6ES7412-5HK06-0AB0	V6.0
CPU414-3 PN/DP	6ES7414-3EM05-0AB0	V5.0
CPU414-3 PN/DP	6ES7414-3EM06-0AB0	V6.0
CPU414F-3 PN/DP	6ES7414-3FM06-0AB0	V6.0
CPU414-5H PN/DP	6ES7414-5HM06-0AB0	V6.0
CPU416-3 PN/DP	6ES7416-3ER05-0AB0	V5.0
CPU416-3 PN/DP	6ES7416-3ES06-0AB0	V6.0
CPU 416F-3 PN/DP	6ES7 416-3FR05-0AB0	V5.0
CPU 416F-3 PN/DP	6ES7416-3ES06-0AB0	V6.0
CPU 416-5H PN/DP	6ES7416-5HS06-0AB0	V6.0
CPU 417-5H PN/DP	6ES7417-5HT06-0AB0	V6.0
CP443-1	6GK7443-1EX11-0XE0	V2.0
CP443-1	6GK7443-1EX20-0XE0	V1.0
CP443-1	6GK7443-1EX30-0XE0	V3.0
CP443-1 Adv	6GK7443-1EX40-0XE0	V1.0
CP443-1 Adv	6GK7443-1EX41-0XE0	V1.0
CP443-1 Adv	6GK7443-1GX20-0XE0	V2.0
CP443-1 Adv	6GK7443-1GX30-0XE0	V3.0
CP443-1 IT	6GK7443-1GX11-0XE0	V2.0

Table 03

Activating the NTP for time synchronization
You set the time synchronization for the CPUs via the NTP in the hardware configuration of STEP 7.
Open the Properties dialog of the Industrial Ethernet CP to enable. In the "Time Synchronization" tab, set a check mark for "Activate NTP time-of-day synchronization".
Enter the IP addresses of the relevant NTP servers in the "NTP Server Addresses" field.

Important

• The NTP mode does not support any automatic changeover between summer time and winter time. This is not provided for in the protocol. You must change the local time accordingly. NTP always transmits the coordinated world time (UTC) or Greenwich Mean Time (GMT). 
  How to calculate summer time is described in Entry ID: 19324378
• You cannot set any time zones when using the NTP time-of-day synchronization mode in S7-300 and S7-400 CPUs.
• In the case of CP343-1 IT with order number 6GK7343-1GX20-0XE0 and firmware V1.0 you must select the MPI address 2 for the CPU when using the "Set CPU time" function. As from firmware V1.1, setting the CPU time is independent of the MPI address, see Entry ID: 21070809.

Example of a time-of-day relay with S7-400 as time slave
In order to be able to use the NTP mode you must enable the "Activate NTP time-of-day synchronization" function in the Properties dialog of the Industrial Ethernet CP -> "Time-of-Day Synchronization" tab. Furthermore, at least one IP address of an NTP server must be specified with the "Add..." button and the "Forward time of day to a station" option must be enabled. The time zone and update interval should be set according to the requirements of the project.

Fig. 01

A list of the active NTP servers (Stratum One Time Servers) is available at this link:
http://support.ntp.org/bin/view/Servers/WebHome

You can use these NTP servers for time-of-day synchronization. In this example the time-of-day synchronization is made by means of the Stratum One Time Server of the University of Erlangen-Nürnberg.

In the Properties dialog of the CPU you must configure the S7-400 CPU as time slave in the "Diagnostics/Clock" tab.

Fig. 02

Example of a time-of-day relay with an S7-300 as time slave
In order to be able to use the NTP mode you must enable the "Activate NTP time-of-day synchronization" function in the Properties dialog of the Industrial Ethernet CP > "Time-of-Day Synchronization" tab. Furthermore, at least one IP address of an NTP server must be specified with the "Add..." button and the "Forward time of day to a station" option must be enabled. The time zone and update interval should be set according to the requirements of the project.

Fig. 03

A list of active NTP servers (stratum 1) is available at the following internet site: http://support.ntp.org/bin/view/Servers/WebHome. These NTP servers can be used for time-of-day synchronization. In our example the time-of-day synchronization is made by means of the NTP server (stratum 1) of the University of Erlangen-Nürnberg.

Since the time-of-day of the S7-300 CPU is repeatedly set from the Industrial Ethernet CP, it is necessary to have a connection resource for this service of the S7-300 CPU. Please bear this in mind when configuring the system.

There is only need to configure time-of-day synchronization for the S7-300 CPU if you are using one of the following Industrial Ethernet CPs:
 

SIMATIC S7-300	Order number	Firmware
CP343-1	6GK7343-1EX30-0XE0	as from V2.2
CP343-1 Adv	6GK7343-1GX30-0XE0	as from V1.0
CP343-1 Adv	6GK7343-1GX31-0XE0	as from V3.0
CP343-1 Lean	6GK7343-1CX10-0XE0	as from V2.2

Table 04

If you are using one of the above-mentioned Industrial Ethernet CPs, then you must make additional settings in the Properties dialog of the CPU. The settings depend on the configuration of the communication bus in the backplane bus of the CPU.

• The communication bus is configured as a party line, in other words it is physically "wired through" to the MPI interface on the CPU. This setup is found in CPUs from CPU 312 up to and including CPU 315-2 DP and the C7 devices. In this case, in the Properties dialog of the CPU you select the "Diagnostics/Clock" tab and set "As slave" for the synchronization mode on the MPI.

Fig. 04

• The communication bus is not configured as a party line, in other words the MPI interface and the communication bus are separate. This bus setup is found in CPUs from CPU 315-2 PN/DP up to and including CPU 319-3 PN/DP. In this case, in the Properties dialog of the CPU you select the "Diagnostics/Clock" tab and set "As slave" for the synchronization mode in the PLC.

Fig. 05

Diagnostics
Open the NCM S7 diagnostics of the Industrial Ethernet CP to determine the status of the time synchronization.

Start the NCM S7 Diagnostics in the Windows START menu by means of "SIMATIC > STEP 7 > NCM S7 > Diagnostics".

Alternatively you can also open the NCM S7 Diagnostics with the SIMATIC Manager. Right-click the Industrial Ethernet CP and select the menu "PLC > Module status". In the "Module status" dialog you switch to the "General" tab and click on the "Special Diagnostics" button to open the NCM S7 Diagnostics of the Industrial Ethernet CP.

Information about time-of-day synchronization in SIMATIC mode or in NTP mode is available in the "Time-of-Day" tab.

Fig. 06

Note the following points when interpreting the display:

Display of configured NTP servers
You can specify up to four NTP servers in the configuration. The relevant NTP servers are addressed by the CP and their reply messages evaluated. The NTP server with the greatest precision is chosen. This ensures that the station with the most precise time is synchronized.

Important here is the Status column. The following displays are possible here:

• NTP master
  The CP accepts the configured NTP server for time-of-day synchronization. The CP assigns this status to just one of the configured NTP servers.
• Reachable
  The configured NTP server is reachable in the network, but is not taken for time-of-day synchronization.
• Reachable (unsynchronized)
  The configured NTP server is reachable in the network, but is not taken for time-of-day synchronization. The CP recognizes from the message that the NTP server is not synchronized.
• Not reachable
  The NTP server is configured but cannot be reached under the specified IP address.

None of the configured NTP servers is displayed as NTP master
Sometimes all the NTP servers are displayed as Reachable - but none as NTP master.

• This indicates that the time-of-day of the NTP servers has been evaluated as imprecise.
  In the CP's firmware there are various checks that are defined in the corresponding RFCs (Internet Standard).
• This might also have something to do with the synchronization of the NTP master. There are multiple time stamps in the NTP message. If an NTP server is not synchronized externally, this is noted accordingly in the time stamps in the messages. The consequence is that the time-of-day of these NTP servers is not accepted.

The fact that there is no potential NTP master among the reachable NTP servers is also indicated to the user in addition by a counter in the diagnostics. In this case the "How often the sampling interval was exceeded" counter is increased by 1 after expiry of the sampling interval.

Note
All CPs that are older than the modules listed or which have an older firmware version do not react to the reply message of an NTP server if the server does not have an even-numbered NTP version, V2.x, V4.x, for example. You must then upgrade the module with the latest firmware version. All more recent modules that support time-of-day synchronization by means of NTP also accept reply messages from other NTP server versions.

SICLOCK TM time-of-day transmitter
The SICLOCK time-of-day transmitter is a separate unit that can transmit time-of-day messages by means of the Ethernet in SIMATIC or NTP mode.

• SICLOCK TM, order number: 2XV9450-1AR23, firmware as from April 2001

The SICLOCK works exclusively as time-of-day master and broadcasts time-of-day messages in Multicast or Broadcast mode by means of ISO Industrial Ethernet. In NTP mode it is also possible to operate by means of a router. The SICLOCK time-of-day can also be synchronized with a central time from a DCF 77 or GPS receiver.

For more parameters please refer to the SICLOCK manual.

Description:
There is no time conversion of the S7-300/400 CPU clock to summer or winter time in automation facilities with integrated time synchronization. Industrial plants with time synchronization are always supposed to be set to winter time In order to determine the current local time (summer time) in the CPU you can use block FC61 "BT_LT" of the standard library "Miscellaneous Blocks". The Online Help for "BT_LT" contains a list of the blocks required in addition. Based on a default basic time, "BT_LT" calculates the current local time by means of data stored in a data block The calculated local time can for instance serve as system time for operation and monitoring devices (e.g. SIMATIC HMI panels) by means of time synchronization.

Fig. 01

Example of a conversion of the CPU basic time in local time and transfer of the local time to the panel

Conversion of the CPU basic time into local time

• Configure a data block according to structure UDT60 of the Standard Library "Miscellaneous Blocks" with the calculation parameters for the local time and the conversion data for summertime and wintertime. This DB must be specified as input parameter "WS_DAT" at the "BT_LT".

Fig. 02

• Read out the basic time of the CPU using SFC1 "READ_CLK".
• Specify the read out basic time as input parameter "BT" at the "BT_LT".
• At the parameter "LT" the local time calculated is issued in the DATE_AND_TIME format.

Fig. 03

Transfer of the local time to the panel

The transfer of the local time determined "LT" to the panel can be carried out via the time-of-day synchronization between panel and CPU. With time-of-day synchronization, the local time determined can be transferred to the panel using controller jobs (14 "Set time" and 15 "Set date"). After executing job 14 or 15, the system time of panel is automatically set with the delivered data.

For more information and sample programs on time-of-day synchronization, see the following entries:
 

Sample programs	Entry ID:
How do you synchronize date/time between a line/graphics operator panel (TD17, OP5, OP15, OP17, TP27, OP27, TP37, OP37) and an S7-300/400 controller with ProTool?	24088798
How do you synchronize the date and time between an S7-300/400 and OP3 (C7-621) with ProTool?	23972743
How do you synchronize date and time between a TP170A and an S7-300/400 controller with ProTool?	23972509
How do you synchronize the date and time between a Windows-based operator panel and the S7-300/S7-400 controller with ProTool?	24079457

Table 1: Sample programs for time-of-day synchronization

Description:
Time-of-day synchronization is supported by all three major product families in the SIMATIC range: SIMATIC S7, SIMATIC S5 and PC. This synchronization can be done both via Industrial Ethernet and via PROFIBUS and MPI. There are two modes available for time-of-day synchronization via Industrial Ethernet:

• SIMATIC mode
• NTP mode (see Entry ID: 17990844)

Time-of-day synchronization via Industrial Ethernet with the SIMATIC mode
This mode is usually used in process automation in conjunction with ISO transport services and is precise to +/- 10ms between the communications processor (CP) and the synchronized CPU with a resolution of +/- 1ms.
Since SIMATIC mode is based on SNAP services (i.e. ISO Layer 2 service) and works with MAC addresses, it can only be used with local Ethernet networks. This mode does not work with IP networks via IP routers, i.e. with configured IP subnets.

Fig. 01

Time-of-day synchronization for the S7-400 station is configured in the Hardware Configuration. In the Properties dialog of the CPU, you select the "Diagnostics/Clock" tab and then select the synchronization mode. You can configure the S7-400 CPUs as time master (time-of-day transmitter) or time slave (time-of-day receiver).
Set whether synchronization is to be in the CPU (synchronization in the PLC) or via MPI (synchronization on MPI). Synchronization in the PLC includes the CPs.
You can select a time interval of between 1 second and 24 hours for the synchronization.

Configuring the S7-400 station as time master (transmitter)
Proceed as follows to configure the S7-400 station as time master.
 

No.	Procedure
1.	In the hardware configuration of the S7-400 station, you open the Properties dialog of the CPU and select the "Diagnostics/Clock" tab. Set "As master" for the synchronization mode in the PLC and select the time interval for the synchronization, 1 minute, for example. Click "OK" to close the dialog.  Fig. 02
2	The time-of-day messages of the CPU are forwarded via the Industrial Ethernet CP to the time slaves in the Industrial Ethernet subnetwork. In the hardware configuration of the S7-400 station, you open the Properties dialog of the Industrial Ethernet CP and select the "Time-of-Day Synchronization" tab. Enable the "Forward time of day" function. Click "OK" to close the dialog.  Fig. 03

Configuring the S7-400 station as time slave (receiver)
Proceed as follows to configure the S7-400 station as time slave.
 

No.	Procedure
1.	In the hardware configuration of the S7-400 station, you open the Properties dialog of the CPU and select the "Diagnostics/Clock" tab. Set "As slave" for the synchronization mode in the PLC and select the time interval for the synchronization, 1 minute, for example. Click "OK" to close the dialog.  Fig. 04
2	The time-of-day messages of the time master are forwarded via the Industrial Ethernet CP to the CPU. In the hardware configuration of the S7-400 station, you open the Properties dialog of the Industrial Ethernet CP and select the "Time-of-Day Synchronization" tab. Enable the "Forward time of day" function. Click "OK" to close the dialog.  Fig. 05

Notes
More information on time-of-day synchronization via Industrial Ethernet

• with the S7-300 is available in Entry ID: 44049612
• with the PC station is available in Entry ID: 44045424
• with SIMATIC S5 is available in the manual "SINEC CP1430", section 6.6 "Setting and Reading the Time" in Entry ID: 12586144.

Description
The Network Time Protocol (NTP) is a standard for synchronizing computer system clocks via package-based communication networks. Although this is usually done via UDP, it can also be transported by other Layer 4 protocols such as TCP, for example. It was specially developed to enable reliable time relaying via networks with variable package runtimes.

The Simple Network Time Protocol (SNTP) is a simplified version of NTP. It is described in RFC 2030. The Network Time Protocol (NTP) is described in RFC 958.

Instructions for Windows 2000, Windows XP, Windows Server 2003 and Windows Server 2008 (32-bit)
Follow the instructions to configure your local PC as NTP server. In this way you can synchronize other devices with the local PC.
 

No.	Procedure
1	Open the registry editor with "Start -> Run... -> regedit".
2	Search for the code "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters".
3	Edit the "LocalNTP" value and set it to 1. Fig. 01 Note If the "LocalNTP" value does not exist in your system, create a new DWORD value. 0 means deactivated, 1 means activated.
4	Restart the computer to make the changes effective.

Instructions for Windows 7 (32-bit and 64-bit) and Windows Server 2008 R2 (64-bit)
Follow the instructions to configure your local PC as NTP server. In this way you can synchronize other devices with the local PC.

No.	Procedure
1	Stop the "Windows Time" service under START > Control Panel > System and Security > Administrative Tools > Services. Fig. 02
2	Open the registry editor with "Start -> Run... -> regedit".
3	Search for the code "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time\TimeProviders\NtpServer".
4	Set the "Enabled" value to 1. Fig. 03
5	Search for the code "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time\Config".
6	Set the "AnnounceFlags" value to 5. Fig. 04
7	Start the "Windows Time" again and set the start type to "Automatic" if not already done.

Note
The instructions below are for configuring the Windows Time service when using an internal hardware clock and an external time source:
 

Windows Operating System	Instructions
Windows 2000	http://support.microsoft.com/kb/216734
Windows XP	http://support.microsoft.com/kb/314054
Windows Server	http://support.microsoft.com/kb/816042

Warning
Changes in the Registry can lead to unexpected problems requiring you to reinstall your system. We cannot guarantee that problems arising from changes in the registry can be solved. Changes in the Registry are entirely at the user's own risk.

Description:
The IEEE standard 1588 is entitled "Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems", in short Precision Time Protocol (PTP). It defines a method and procedure for synchronizing multiple distributed real-time clocks that are linked via a package-relaying network. PTP is designed for implementation via Ethernet, but not limited to this. In principle any other package-relaying protocol that supports multicast addresses can also be used. The concept isolates the CSMA/CD layer from the upper application layer. In practice control of a process can thus be decoupled from the data transfer protocol.

However, this function is not supported by SIMATIC controllers or CP343-1/CP443-1.