Time server

We want to syncronise the date and time of our S7 414-3PN plc's (date and time need to be up to date.
With that kind of plc I suppose a timeserver on the network where they are all connected must be the easiest way.
The electrical man I am in contact with did not know if a time server was present on the factory profinet network.
I would ask here for the experiences of other people with the presence of a time server in factories.
Is it normally present? If it is not, what are the things the IT-people have to do?
I know there is also some device from siemens that you can put on the network that receives the date and time from the 'atom clock' somewhere in Germany. Who has experience with that? What to do then to have this time in the plc's?

I use a lot of GPS based time-server but don't know much about S7 PLC. You first need to find out what kind of time signal that S7 PLC will sync with, iRIG, NTP, or PTP or some other proprietary system.

Once you determine that then you need to find a source, typically, you have the choice of using a internet based time server (NTP) or a local GPS based source.

Don't know about factory networks. It is common practice on office networks to have one or more servers offer an NTP service in order for PC's and other network devices to sync their clock to that NTP server. In turn, the server usually gets time from a time server on the internet. Typically from pool.ntp.org or an underlying continent/country pool. PCs can also be configured to run an NTP server. I have used that occasionally.

On a larger factory network where syncing of time is relevant I'd get IT to set up an NTP server. Careful if it gets time from the internet. I prefer factory networks to be rather rigourously disconnected from the internet, yes you may call me paranoid - better safe than sorry.

There are also radio clocks. The principle is somewhat similar but not exactly the same. You mentioning the Siemens device is the first time I hear about such a device for industrial use. Must be something like that: picking a clock signal from the air and offer NTP service on your network.

I think most of the PN Siemens controllers support acting as NTP clients, which means you'd need an NTP server on the network. Your IT group would need to either allow you access to one of their servers, or add a device on the network that would provide the function.

Note that there are two goals with time synchronization: Matching the "correct" time at some atomic clock somewhere, and getting all the local devices at the same time. In my experience, industrial facilities are primarily concerned with the second goal: making alarm times match across devices, things like that.

If your industrial ethernet network is airgapped from the rest of the network (and therefore the internet), you won't be able to reach back to an external NTP server tied to an atomic clock. You have two choices, just do a local sync, or sync to some local master like a GPS clock.

I know Siemens had time masters for Profibus systems, didn't know they existed for Ethernet as well. They are probably just GPS clocks. I think there is a "Simatic Time Protocol" or something similar that they support.

Do you need precise synchronization or only time setting?

https://support.industry.siemens.co...f-an-s7-controller-from-wincc-?dti=0&lc=en-WW

My experience is in the offshore world and it is very common there to have a GPS receiver to be the time server. Due to the complexity of the installation, the PLC's don't synchronise directly with the time clock and instead a router takes its time from the GPS and all the PLCs sync to it.

You can configure this in the hardware config easily.

There is a desktop pc (with windows 7) for the scada on the factory network.
Is it possible to set this up as a timeserver (NTP) for the S7 plc's?
If so, what does it involve to do so?
Or does it need to be a 'real server' and not an ordinary pc?

Assuming S7 can be NTP client then yes, you can use a Windows 7 PC as time server. It involve editing some registery parameters. There are apps that make this easier. I haven't used this one but Meinberg is a well know time-server company:

https://www.meinbergglobal.com/english/sw/ntp-server-monitor.htm

harryting said:

Assuming S7 can be NTP client then yes, you can use a Windows 7 PC as time server. It involve editing some registery parameters.

Click to expand...

Correct, I have done that on several occasions with both W7 and W10 PC's. Plenty of information on the internet on how to do it.
https://stackoverflow.com/questions/28380984/set-an-ntp-server-on-windows-7
https://serverfault.com/questions/390061/windows-7-as-ntp-time-server

With some warnings that not all NTP clients will sync correctly with a W7 NTP server. It has worked fine on PLC's for me.


One thing to keep in mind: if the PC runs Windows firewall, then you will have to allow NTP traffic. That is UDP port 123, inbound and outbound - the latter if you want the PC to also sync with another server.
https://www.meinbergglobal.com/english/info/ntp-w32time.htm