PLC Time Sync with SCADA Server

whussain6

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Join Date
Oct 2013
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Newcastle
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I have CLX PLC v28.11 and SCADA (ww Archestra Platform) on Windows Server 2012. I want the PLC to get time daily from the SCADA Server.

I have tried the Logix5000 Clock Update Tool but it does not seem to be reliable. It only updates PLC time intermittently.

The Other option is to send time from SCADA application using some scripts but I am looking for a neater method to do this using NTP.

Kindly, your ideas to Sync CLX to PC (Server) time without scripting SCADA/PLC?

Regards

Wajid
 
I would normally use NTP to synchronize a device's clock to a PC. It's pretty good, especially if you only need to be pretty close (less than a second, maybe less than 100ms).

Does Logix support NTP via its Ethernet cards?
 
Does Logix support NTP via its Ethernet cards?

The newer 1756 Ethernet cards support "CIP Sync" which can be synchronized with a costly 1756HP-TIME module using NTP as an option. CIP Sync can also use a Windows service, and therefore NTP, as the grandmaster clock.
 
I would encourage you to revisit the RSLogix 5000 Clock Update Tool.

In general, it updates the clocks "periodically" on a scheduled basis, rather than "intermittently". What periodic rate have you chosen ?

How much clock drift are you experiencing ?

Are there other network connectivity issues that are causing the controller clocks to not be updated by the RSLogix 5000 tool ? Certainly if you don't have good enough network reliability for a simple PC service to connect to the controllers, the network's not going to support high-performance clock synchronization.

I wish the ordinary 1756 Ethernet modules had an NTP feature, but they just don't.
 
The newer 1756 Ethernet cards support "CIP Sync" which can be synchronized with a costly 1756HP-TIME module using NTP as an option. CIP Sync can also use a Windows service, and therefore NTP, as the grandmaster clock.

I have been reading up on this and apparently the network cards support the PTP protocol natively but not the NTP protocol without that special card.
PTP doesn't come by default in Windows, so perhaps some additional software can do that.
One other option I've seen floating about is to take a computer running Linux and set it up as a PTP server. If you went with one raspberry pi type board, you could even plug in a GPS receiver module and not have to worry about having correct time on your control systems... although that may be tricky to get implemented in large companies.
 
I wish the ordinary 1756 Ethernet modules had an NTP feature, but they just don't

Hi,

Pretty sure the 1756-EN2TR modules support NTP time sync. We have used the Rockwell supplied AOI a couple of times successfully (see attached).

Regards,

Rob

L5K_NTP.jpg
 
Thank you all for your input

What periodic rate have you chosen ?

I have 1 hour period and it successfully synced first time by the clock update tool but then I changed the PLC time by 10 seconds but it never synced again. I have definitely selected the only PLC in the event schedule and the schedule trigger configured to recur 'Every hour' and never end is selected.
BUT!!!!!!!!!!!! doesn't work

network connectivity issues
The response time on logix5000 tool is 34-45ms so I don't think it is connectivity issue.

FYI: I have only 1756-EN2F with 1756-L71 controller. Nothing else in the rack. I have two separate servers (Programing/Logix and Runtime/SCADA) on the domain. Off course both servers will get there time synced by domain controller.

In summary, I need to use AOI to sync time with PC using NTP? Is there anything I need to setup on PC side?
 
Working Logix5000 Clock Update Tool

Hi Guys,

My Logix5000 Clock Update Interval is working after I re-created my schedule...eeh....but yes it seems to be working for 5 consecutive hours so fingers crossed.

Just questions about how to start up and what happens if I close it? I found Start-up option when windows starts...does it require logix running? What happens if the PLC is not there?
 
Last edited:
I closed and reopen the CUT (Clock update tool) and now after sometime it is showing 'RSLinx Classic Communication Server has stopped working'. I am sure I have seen this before when it stopped working afterwards.
 
Cool, Rob ! I knew that you could roll your own NTP client, but didn't know it had been done effectively in an AOI.

As for whussain's RSLinx crashes, I suppose he needs to start troubleshooting those, maybe beginning with the Windows event log.
 
Sntp aoi

Hi Rob I have tried your suggestions (thanks) and it works.

The question now is what about time zone and 'Day light saving' etc?:)
 
The question now is what about time zone and 'Day light saving' etc?:)

There is also a Rockwell Sample Code AOI to adjust the clock setting for Daylight Savings Time: the DST AOI.

Note that you need a socket-compliant Ethernet module to use the SNTP AOI. As I found out the 1756-ENBT will not work.

A list of compliant modules can be found here: Ethernet/IP Socket Interface
 
Can this be emulated?

Hey Rob (or anyone else who has worked with the SNTP/NTP AOI),

I got a SNTP AOI from Rockwell, but can not get it to work!

What is the correct NTP server's IP Address to be used, and how do you know?

Can this be tried out on a emulator or is it not possible because we need the 1756-EN2T to be running?

Any information is appreciated!
 
I don't know much about the AOI. However, the IP address it request should be quite self-explanatory. It's whatever the IP address for your NTP server.

Any Windows machine can be a NTP server. I have found that sometime they tend to be a bit flaky though. I very much doubt it would work on a emulator.
 
What is the correct NTP server's IP Address to be used, and how do you know?
Ideally each organization should maintain their own NTP server but there are a huge number of public NTP servers around the world. You should generally use the closest one to you. Check out pool.ntp.org

When in doubt try Google's public NTP servers time.google.com 216.239.35.0.

To test an address, set your clock wrong on your PC, then use windows internet time with the above address. NTP can be blocked by your Internet provider (who should provide an NTP address for their users).
 

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