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I have control systems worldwide that I monitor remotely, PLC / HMI based with a headless Intel NUC within the network.
Each system has a 4G modem which works well 99% of the time, but occasionally it drops off generally to poor reception and requires a reboot.
I have wired the power to the Modem through a normally closed contact of a relay controlled by the PLC for a future possibility of monitoring the Internet access and automatically rebooting the modem.

I was hoping to find a software package that could monitor the internet and provide its status to the PLC via TCP Modbus.
To me, this doesn't seem overly difficult, but unfortunately, I do not have the skill base to do it.

Can anyone suggest a solution?

Kind Regards

What I have tried:

The PLC can send emails, and I was considering sending an email every 30 minutes or so and monitoring the successful status bit.
I'm not overly keen on this option, hoping there is a better solution.
Updated 24-Dec-22 13:57pm
Peter_in_2780 12-May-22 19:10pm    
Periodic email is a bit of overkill, I agree.
I monitor internet accessibility by using ping to a well-known address, like or
Brad Winters 13-May-22 4:44am    

Something of this kind is so easy to implement in code. Pretty much ping or access programmatically any known address, like and if it is timesout or gives socket error use OS API to reboot the system. It needs to be a service so it will start every time machine restarted and does not require actively logged in user
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Brad Winters 13-May-22 17:08pm    
Are you looking for a Free/Paid versions of software packages?
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