EtherCAT is a point-to-point protocol so it doesn't need a unique MAC address. It would be very useful to set the MAC address to 020000000000, the standard address for this kind of application. (The important bit is the 02 at the start of the address, which means locally-administered MAC.) The stock Windows driver can do this for my i210 card. But the CODESYS CmpEt1000MPD driver cannot. The image shows the setting with the Windows driver. If I set all my customers' cards to this address, then I don't...
Monitor what your current cycle time is (in the Task Configuration when you are online). If this is sometimes close to 200ms, then change your code (e.g. limit the loops, or prevent copying a lot of data between objects). Or just set the Watchdog time (or sensitivity) higher if you don't care that it sometimes takes longer than 200ms. If you want to find out which objects in your application consume the most time, then buy a PDE (Professional Developer Edition) license. With this you get a license...