What are some resources for learning about the history of dry contact relay technology?

When the device raises an alarm (e.g., Ethernet link down), the device reports the alarm's severity level (Minor, Major, or Critical) to the external alarm ... Ec Pick-Up Assy Dry Contact Relay W Pigtail (6-Pin) · Additional information · Related products · Laser Sensor W Bracket · Knife Solenoid Assy – 110V · Relay ... Description. The ELK-912 is a high quality 12 Volt DC relay with SPDT (Form "C") dry contacts. It features low current draw, positive or negative activation ... Ground (GND). Dry Contact Inputs (A and B): Trigger relays using external dry contacts such as switches, sensors, access systems, or automation controllers ... Aug 17, 2021 ... Also known as a passive contact, dry contacts don't have power or voltage supplied directly from the switch. Instead, it comes from another source. Connect dry contact relays and aftermarket smart garage door controller to Security+ 2.0 LiftMaster, Chamberlain or Craftsman opener with yellow “learn” button. Output dry contact relay for PRIMUS sterilizer. Part Number: 400118. This product can only be purchased by Spire partners/members. To purchase this product, ... dry contact outputs are specified or whenever normally closed contacts are required. Good choice for specifications that call for contact closure outputs. Functional Devices, Inc. RIB Dry Contact Relay, 10 Amp SPDT, Class 2 Dry Contact Input, 120-277 Vac Power Input, NEMA 1 Housing. Nov 30, 2024 ... TLDR: Can I use a Shelly to monitor a dry relay and log anytime the circuit is closed vs open? Which model(s)?