ST-121F Kollmorgen
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The Kollmorgen ST-121F is part of the Crevis Slice Modules series and includes 16 sink type input channels with a typical filter time of 1.5 milliseconds. It consumes 45 mA current at 5 VDC and mounts on a 35 mm DIN rail. The module measures 12 by 99 by 70 mm and weighs 70 grams.
Internal Product Review
The ST-121F is a 16-channel digital input slice module built for sink positive-logic input applications. A typical 1.5 ms filter time and 3 ms maximum input delay support clean, responsive signal handling in control circuits. 35 mm DIN rail mounting and 45 mA at 5 VDC current consumption make the module an efficient choice for compact control panels.
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Product Description:
The ST-121F digital input slice module is manufactured by Kollmorgen for its Crevis Slice Modules series. Designed for distributed I/O racks, it receives field-level signals and forwards them to a host controller over the Crevis backplane. In an automation cell, the module converts 24-volt sensor transitions into logic-level status bits, allowing PLCs to monitor limit switches, proximity sensors, and other discrete devices without occupying controller-side wiring. This distributed arrangement reduces the amount of field wiring routed directly to the main controller.
The module draws 45 mA from the 5 VDC internal bus, a value that helps determine the total power requirements of a slice stack. The module provides 16 isolated inputs for compact monitoring of multiple sensors on a single slice. Each point uses sink inputs with positive logic, meaning external devices source current while the common terminal is connected to ground. With an input impedance of 5.1 kΩ, the module limits the current drawn from connected sensors. Signal conditioning is performed by a programmable filter with a typical setting of 1.5 ms, which suppresses contact bounce while maintaining responsive operation. The circuitry accepts nominal 12/24 VDC field signals, recognizes the on-state at the applicable minimum voltage, and remains off below the 5 VDC maximum. Each input permits up to 6 mA of sensor current at 28.8 VDC.
A spring latch secures the module to a 35 mm DIN rail, allowing tool-free removal during maintenance. Propagation through the optocoupler network adds a maximum delay of 3 ms between a field transition and the corresponding backplane data update, which is suitable for typical interlock timing. The plastic housing measures 12 × 99 × 70 mm, allowing dense I/O clusters to fit within limited panel space. The module weighs 70 g, which minimizes the load placed on the rail and enclosure supports. Its slim housing also leaves more room between adjacent components for wiring access and internal airflow. The compact format allows multiple slice modules to be arranged together without requiring a large mounting area.
