Real Time Clock (RTC) in X90 controller

When using the X90 controller in mobile equipment, sometimes the equipment is powered off for a while. This can cause the condensator for the Real Time Clock (RTC) to drain which resets the time. Till now, we always added a third-party RTC component in the equipment which is used to check and set the RTC of the X90.

Does anyone has encountered the same problem and is there another solution to this problem maybe without using a third-party component?

While it won’t inherently solve your problem, our controllers are able to be configured as NTP clients and connected to an NTP server. This may be an easier method of ensuring the accuracy of the RTC than what you are describing, though it doesn’t eliminate the need for third-party hardware. See the linked Help page for more information about configuring the NTP server.
CPU properties - Time synchronization (NTP)

Hello Andrew,

Thank you very much for the response!
I’m aware of the NTP functionality, and I’ve used it already with systems that can connect to an NTP server.
However, we also make mobile equipment that doesn’t connect to any network, so an NTP server is no option there, unfortunately.

So if I’m understanding correctly, apart from power on the equipment regularly, a third-party RTC component for synchronizing the clock is the best solution in these situations?

According to the technical data, the RTC should remain stored for approx. 250 hours. To extend the time it helps to switch on the X90 within 250 hours. Alternatively, you could use another B&R controller or a Raspberry PI as an NTP server. However, there is certainly a specific reason (temperature range or vibration resistance) why you chose an X90 controller. Therefore, the use of a Raspberry PI as an NTP server must be checked beforehand.

Hello Stephan,

Thank you.
I’ve searched for industrial time servers and found one of Phoenix Contacts. Unfortunately, it is ’ out-of-stock’ for now…

When no NTP server is available at the client, and no industrial NTP Server is available, i think the CAN Bus RTC Component we are using now is the best option for our equipment as far as i can see.

If you are using a X90CP174.48-S1 you can simply keep power on V_I/O and turn off V_CPU. This will switch off the module and still keeps the RTC active.

Unfortunately this won’t work for the X90CP17x.xx-00 (non safety) as the RTC is supplied by V_CPU.


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Hello @c393702

Due to one month of inactivity, this post will be marked as solved. If you would still like assistance on this topic, please add a new reply with the latest status :slight_smile:
Thank you.