Operating two autonomous machines in synch

[patpopcorn]

I need to operate two autonomous machines within + or - 1 second accuracy all year. One mile apart. How do I synch the clocks? wwvb or gps? I don't want to use rf signaling. I want to synch the clocks and calenders.

any suggestions?

 

[Money4Nothing]

What are the machines controlled by? DCS, PLC?

$

 

[patpopcorn]

I haven't built it yet. Which do you suggest?

 

[patpopcorn]

I don't want the controllers to communicate with each other. I want to seperately program them but synchronize the clocks.

 

[patpopcorn]

Are there dcs's or plc's with gps or wwvb controlled clocks?

 

[Eddie Willers]

Within 1 second isn't too hard because you can buy an older GPS unit with an RS-232 output and just read the serial strings it sends out to get the current time from a satellite. I've done this with an ancient Earthmate I bought surplus to keep a pump station's time accurate.

Some PLCs have GPS modules available that include the satellite time as part of the signal. The one I'm most familiar with is the HIPROM GPS module for ControlLogix. This will give you very accurate time but isn't cheap.

If these machines are connected to a plant network or other WAN that includes a Network Time Server and there are computers that are known to have an accurate time, then you should be able to easily keep their times in sync by sending the computer time to the machine. Again, the software I'm most familiar with is the Logix 5000 Clock Tool that sets the time on multiple PLC/SLC/Logix controllers based on a computer workstation time.

 

[patpopcorn]

Thanks

thanks,

Is there any way you could synch a device with an wwvb clock, like in an radio based "atomic clock"?

 

[patpopcorn]

I checked the prices--so much for the cheap and easy solution. I'll look into gps. I talked to a manufacturer, they said they were looking into how to make such a beast.

 

[timbo_uk]

What about these modules and make one up yourself?

http://www.ntp-time-server.com/wwvb-receiver/wwvb-receiver.htm

 

[leitmotif]

I need to operate two autonomous machines within + or - 1 second accuracy all year. One mile apart. How do I synch the clocks? wwvb or gps? I don't want to use rf signaling. I want to synch the clocks and calenders.
any suggestions?

I ask mostly to learn but also curiosity.

If the two machines are autonomous ie completely independent why the need to synchronize their time base?

The one reason I can see is for data logging purposes ie two sets of data referanced to same day and time to allow for consolodation ease.

Dan Bentler

 

[patpopcorn]

The application has to do with an irrigation system -pumps and valves.

 

[milldrone]

thanks,

Is there any way you could synch a device with an wwvb clock, like in an radio based "atomic clock"?

I use one of these.

http://www.time4weather.com/lacrtewtpral.html

I hacked into the piezo buzzer circuit. By using a SSR with 3 to 30 volt input.


Set the built in alarm for 4:00 in the morning. Then adjust the PLC time to the alarm. It takes care of daylight savings time also.

 

[timbo_uk]

I use one of these.

http://www.time4weather.com/lacrtewtpral.html

I hacked into the piezo buzzer circuit. By using a SSR with 3 to 30 volt input.


Set the built in alarm for 4:00 in the morning. Then adjust the PLC time to the alarm. It takes care of daylight savings time also.

Ingenious