The AES 1102 and AES 1112 have a triple redundant structure for monitoring guard doors. A first fault can lead to a failure of one of the three channels, whereby the two other channels maintain their safe function.

The AES 1235 safety-monitoring modules have a dual-channel structure. They include two safety relays with monitored positive action contacts. The NO contacts of the relays, which are wired in series, build the enabling contacts.