Driving external power relay/contactor with NetControl is a common application due to the limited power of the built-in relays. The management of such a load (with a pronounced inductive character in switched mode) causes powerful voltage spikes in the supply wires, and they penetrate as interference in NetControl.
The new hardware version of NetControl (core v2) found an increased sensitivity of the Ethernet chip to such interference, causing temporary failures in the link or link loss at all (restored only after restarting the entire device). This is observed when the contactor is switched off.
We are in the process of searching for a software solution against the "hanging" of the link, which can not solve the problem at all, but at least will prevent losing access to the device.
The only sure solution is to filter the interference, which is possible with the so-called 'Snubber', parallel to the contactor coil. The effect is strongest when installed directly on the contactor without long wires. The filtering circuit is a follow-up RC group.
NEW!!! As of 27.08.2018 we offer ready to install filter - ACS40.