Reliable Discrete Input and Output Processing
This relay I/O module provides robust discrete signal handling for distributed control systems. It combines eight digital inputs and eight relay outputs in a single compact unit. The Yokogawa AMN21 accepts 24 V DC digital signals from field sensors and switches. Each relay output handles up to 2 A at 250 V AC or 30 V DC loads. The module offers optical isolation between the field side and the internal logic circuits. It features individual LED indicators for each input and output channel status.
Physical Dimensions and Mounting Specifications
The unit measures 120 mm in height, 70 mm in width, and 130 mm in depth. It weighs approximately 0.75 kg with all terminal blocks and mounting hardware attached. The AMN21 mounts securely onto a standard 35 mm DIN rail inside the control cabinet. Its robust steel housing provides excellent protection against mechanical stress and vibration. This durable construction ensures reliable operation in demanding factory floor environments.
Connectivity Options and Electrical Requirements
A front-facing screw terminal block facilitates all field wiring connections for inputs and outputs. The Yokogawa AMN21 draws its operational power from the 5 V DC backplane supply. It communicates with the host controller through a serial communication interface. A DIP switch array allows users to set the module address for system identification. Front-panel LEDs display power status and individual channel activity clearly. These visual aids significantly reduce troubleshooting time during maintenance.
Internal Architecture and Energy Storage Elements
The PCB contains eight optocoupler input circuits and eight electromechanical relay output circuits. Each relay features a mechanical life rating of 10 million operations minimum. The AMN21 stores configuration parameters in non-volatile EEPROM for reliable startup. A 100 µF capacitor provides local energy storage for transient voltage suppression. The module also includes flyback diodes across each relay coil for back-EMF protection. This protection extends the life of the output switching components significantly.
| Parameter | Specification |
|---|---|
| Model | AMN21 |
| Type | Relay I/O Module |
| Digital Inputs | 8 channels, 24 V DC |
| Input Voltage Range | 10–30 V DC |
| Input Current | 7 mA per channel (typical) |
| Relay Outputs | 8 channels, Form A (SPST-NO) |
| Contact Rating | 2 A at 250 V AC / 30 V DC |
| Mechanical Life | 10 million operations (min.) |
| Electrical Life | 100,000 operations (rated load) |
| Isolation | 1500 V AC (field to logic) |
| Supply Voltage | 5 V DC (backplane) |
| Dimensions (H×W×D) | 120 × 70 × 130 mm |
| Weight | 0.75 kg |
| Operating Temperature | 0 to +55 °C |
| Storage Temperature | –20 to +70 °C |
| Interface | Serial backplane bus |
| Field Connector | Screw terminal block |
| Address Setting | DIP switch (8-position) |
| Energy Storage | 100 µF capacitor |
| Output Protection | Flyback diodes on relay coils |
Recommended Installation Practices
Position the Yokogawa AMN21 away from high-voltage power distribution equipment. Use separate cable trays for input wiring and output wiring to avoid crosstalk. Connect all input devices using shielded cables for reliable signal detection. Verify the correct relay contact rating matches your field load requirements. Test each input and output channel individually after completing the wiring. Schedule periodic inspections to check relay contact wear and terminal tightness.
Details
| Weight | 0.75 kg |
|---|---|
| Dimensions | 120 × 70 × 130 mm |
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