We have Mark6 controller, which controls two GTs. We have one server HMI in main control room for each turbine, and one local server HMI located on each control panel per each GT. So the total is 4 servers. One HMI only is the master for the time synch signal, and it has a time card. All the HMIs are connected via the UDH network. What is the best configuration for the master and its client HMIs (with the point of view of unicast and/or broadcast NTP communication way)? And can one NTP in the proper configuration produce high traffic in the UDH or PDH?

Thanks a lot.

 

Are you experiencing problems with time synchronization? If so, please tell us what issues you are experiencing and when they began occurring (for example, after some NTP configuration change, or since commissioning, or since an HMI was "rebuilt", etc.).

If not, why do you feel it necessary to change the current configuration?

Have you looked in the manuals or on the HMI for any documentation or help files for NTP?

The help available on an HMI for NTP is usually pretty minimal. However, I'm told the version of NTP provided on HMIs is an open source software version of NTP, so you should be able to search the Internet and find some helpful information.

 

Does Mark VI access NTP Servers (NTP Servers: 209.81.9.7 or 207.46.130.100) via open internet to update its time?

BR,

Zhuong

 

First, thanks a lot for your fast reply.

I have searched in the manual of both NTP and NTP server before sending my question. I found (NTP server manual GEI-100507A) that if master HMI is configured as both unicast and broadcast, "the case in our control system", the client HMIs to be configured broadcast if in the same subnet, and to be configured as unicast clients if in remote subnet.

The case is that in our system, all clients are configured as both unicast and broadcast. May this configuration produce any network traffic? Moreover, the problem is that both turbines have tripped at the same time. We consulted GE, the preliminary report of GE after gathering some information and historian data tells us that there is high network traffic make it difficult to see the exact problem source. They want to review some parameters, one of them is the NTP configuration. The important thing is that this trip happened few days after site visit of the GE representative who invited to adjust the time stamp between the Mark 6 and DCS. Because there were differences between the Mark 6 and DCS alarms in terms of their output time. And the problem of time stamp is solved after this site visit.

In the moment I am trying to search the internet as well.

Thanks a lot.

 

Not at most power plants. Internet access for turbine control systems is usually either denied or severely limited for security reasons.

Most power plants use some form of satellite-based time signal (IRIG-B or I've heard some have some kind of GPS-linked source).

 

I don't ever recall seeing a site with the NTP Server configured as both broadcast and unicast. Is the DCS getting it's time synch signal from the Mark VI HMI over the PDH or from the same source that's supplying the Mark VI HMI? Could that be the reason for having it set to both broadcast and unicast?

My recollection is that most Mark VI sites were configured as unicast, but it's been a while since I've worked on a Mark VI site.

But, you should wait for GE's reply.

My experiences with high network traffic are that it's usually caused by problems with CIMPLICITY project configuration or problems with too much data being requested by a DCS at a very high rate, or, asking for data from invalid signal names, or both.

 

Thanks a lot, once again, for your reply.

About your question, "Is the DCS getting it's time synch signal from the Mark VI HMI over the PDH or from the same source that's supplying the Mark VI HMI?" I could not answer this right now. But I will investigate and answer you soon (GOD willing). Moreover, after receiving the final report, I will inform you about final problem source and its solution.

But, have you seen client HMIs configured as both unicast and broadcast, from your experience?

Once again, thanks a lot.

 

No. I've never seen any Mark VI Speedtronic NTP "node" (client or sever) configured as both Unicast and Broadcast. Having said that, it's been a while since I've seen a Mark VI installation, and it might be done if clients were on separate subnets per your earlier response. That's why I was asking if the DCS was getting it's time synch signal from the HMI Master, because it might be on a different subnet.

Just a guess. I'm not a network expert.

 

Dear CSA,
Thanks a lot for your reply.
Again, if I have any further notification from the Vendor, or I catch any result I will contact you.

Thanks a lot for your usual support.