Fisher TYPE KM1421 High-Low Limiter Module

The Fisher KM1421 is a high‑low limiter module used in legacy Fisher control and automation systems. It provides adjustable high and low limit functions for analog process signals, enabling protective limiting, override logic, and constraint‑based control actions in distributed or panel‑mounted systems. This plug‑in card is designed for rack installation and includes onboard fusing and signal conditioning components. Made in USA. Technical Specifications: Model: KM1421 High‑Low Limiter Module (Fisher part no. 42A4524B) Function: Provides high‑limit and low‑limit signal conditioning for automation/control loops; used to enforce process constraints in analog signal paths Module format: Plug‑in PCB module for Fisher control racks; front panel with status indicators Onboard protection: Twin signal-path fuses installed on PCB Dimensions (typical for KM‑series modules): approx. 11.5 in × 7.5 in × 1.75 in (from KM1421 listing) Weight: approx. 0.8–1.8 lbs depending on revision and packaging (multiple listing data) Manufacturer: Fisher Controls, part of Emerson Automation Solutions Typical application: Limit override logic, safety constraint functions, signal limiting in industrial process control loops Country of manufacture: USA Please review pictures carefully and let us know if you have any questions!