S7-1511 Time synchronization failure

Hi,

I am using an S7-1511F and WinCC Professional V13 on a windows server 2012 R2.

I am trying to set up time synchronization between PLC and SCADA using NTP but i get the following error:

"CPU Maintenance required: Time synchronization failure: No time synchronization with time master" Event ID: 16# 02:4054.

I have activated NTP on the server according to the attached manual.

The server is not a domain controller and does not have any internet connection. Could this have anything to do with the error?

In the HW config i have set the IP-address for the SCADA server and an update interval of 30 s.

Hi ccduii,

did you ever solve this? I get exactly the same error using an independent Linux machine as the NTP master on a S7-1517TF-3.

I captured the network traffic and can see that the PLC sends the request to the NTP server and receives a response within a fraction of a ms but immediately after receiving the response the PLC sends another request and that second request is not answered... after these three packets the PLC waits for the configured 10 seconds and then the same happens again. It almost looks like the PLC does not "like" the response and therefore tries again.

ccduii

"CPU Maintenance required: Time synchronization failure: No time synchronization with time master" Event ID: 16# 02:4054. 

Looks like my issue was on the server side. Checking out the NTP packets in Wireshark a little further I realized that the server replied with a "RATE" reference in the first place - meaning that the server temporarily denies access because the client exceeded the rate threshold... and that's why the second request was not answered at all.

Adjusting the rate threshold on the server side fixed that and now the error message is gone. For testing removing the "limited" flag from the relevant "restrict" command in /etc/ntpd.conf was good enough to confirm that this is the root cause.