# How to identify bottleneck of data refresh rate?

**URL:** <https://forum.inductiveautomation.com/t/how-to-identify-bottleneck-of-data-refresh-rate/6835>\
**Category:** General Discussion\
**Created:** [July 9, 2013, 10:12am UTC](https://forum.inductiveautomation.com/t/how-to-identify-bottleneck-of-data-refresh-rate/6835 "2013-07-09T10:12:58Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![maxi0361](https://avatars.discourse-cdn.com/v4/letter/m/3bc359/32.png) [@maxi0361](https://forum.inductiveautomation.com/u/maxi0361)\
**Post date:** [July 9, 2013, 10:12am UTC](https://forum.inductiveautomation.com/t/how-to-identify-bottleneck-of-data-refresh-rate/6835/1 "2013-07-09T10:12:58Z")

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I use OPC foundation .Net stack to subscribe 500 nodes from a Ignition gateway within VPN.

the timestamp of data received is 2 minutes behind current PC clock time.

Don’t know what is causing this 2 minutes delay, PLC? SCADA? OPC Gateway? network congestion?  
How do I identify the problem?

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [July 9, 2013, 12:14pm UTC](https://forum.inductiveautomation.com/t/how-to-identify-bottleneck-of-data-refresh-rate/6835/2 "2013-07-09T12:14:46Z")

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Have you checked to make sure the clocks on the two machines aren’t just two minutes apart from each other?