The FLM‑420‑O1I1-D Output-input Interface Modules are fitted with one output to control external devices and with one monitored input. The semi-conductor output is electrically isolated from the
LSN loop and protected against short circuits. The FLM‑420‑O1I1-D Output-input-Interface Module provides two monitoring functions: Monitoring of a line by an EOL resistor, monitoring of a potential‑free contact.