Micro 820 RTC how to sync?

asteroide

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Join Date
Jul 2010
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der
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Hello Friends

We have 4 Micro 820 (2080-LC20-20QWB) and We are using the built in RTC, the problem is that it is not exact.

In one month We have a difference of 15 seconds or more between RTC PLCs.

Is it posible to sync the RTC in the 4 PLC? How could We do that?

Thanks in advance
 
All they all on the same network? If so, use the SNTP.QUERY function to get time from a local server and use the same time server for all 4 micro820.

You can program to update as often as needed.

If on different networks this would become more tricky if your time needs to be very precise.
 
The Micro 820 doesn't support time synchrosiation through NTP server
see this Technote: https://rockwellautomation.custhelp.com/app/answers/detail/a_id/510414

also this one about time drifting in Micro 820: https://rockwellautomation.custhelp.com/app/answers/detail/a_id/611484

In my opinion you can use one plc as a Master and update the RTC of the 3 others

Actually by using the Function block I listed and the set-RTC function it does support NTP time server's.

Please see attach files and it will show you how.
 
Hello, thanks for your response.

All of they are in the same network.

What do you mean a local server? a PC connected always to the PLCs? an HMI o what else?

In the other hand, in case that a PLC were used as a master how we can update the time in the other PLCs?


Thanks again
 
Local Time Server = A PC that gets its time from a "NTP SERVER" and then all 4 plc's gets their time from that PC, or a local HMI.

You could also setup one of the PLC's as a time server and let the other 3 get their time from that PLC. (Note: This will require a little more programming - because now you will have to communicate between the PLC's)

Here's how I do this, all of our HMI's have built in "NTP TIME" service, so I set this up and make sure it's working as I want. Then I use my date/time variables from the HMI to keep my PLC date/time updated.

Just study the information I provided and you should be able to get it working.
 
Hello, sorry to revive an older post.
I'm having the exact same issue, I have 20 Micro820 that need to synchronize their RTCs, I'm doing it via HMI now but I really wanted them to do it by themselves. There's an sntp server in the same network, but I can't get the RA_SNTP_QUERY block provided from RA to work. The socket is written correctly to the sntp server, but I don't get any answer. Server is working properly and serving time to other devices on the network, so it must be a PLC related issue. Anybody has had the same problem? (And solved it?)
 
Yes, I'm using CCW12, all PLCs have firmware versions 11 or 12.
The ntp server is a pc with Windows Server 2016.
Well, if it works for you then I'll keep testing.
 
Last edited:

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