Samsung SSAS21-DI Digital Input Module
Samsung SSAS21-DI Digital Input Module is a high-density discrete signal input module designed for the Samsung SSAS21 programmable logic controller (PLC) and industrial automation platform. Built to capture digital status signals from field sensing devices, the SSAS21-DI converts raw binary inputs into isolated logic states processed directly by the central CPU.
Technical Parameter List
| Parameter | Specification |
| Model Code | SSAS21-DI |
| Series | Samsung SSAS21 PLC System |
| Module Type | Discrete Digital Input Module |
| Input Points | 16 / 32 Points per Module |
| Input Voltage Rating | 24V DC (+10% / -15%) |
| Input Current | Approx. 5 mA to 7 mA per point |
| Isolation Type | Photocoupler (Optoelectronic) Isolation (1500V AC) |
| ON/OFF Response Time | ≤ 1.5 ms (OFF to ON) / ≤ 3.0 ms (ON to OFF) |
| Input Filter | Hardware RC filter + selectable software delay |
| Status Display | Individual Channel LED Indicators (Green) |
| Internal Power Consumption | Supplied via backplane 5V DC bus |
Core Advantages & Product Features
High Noise Immunity: Optocoupler isolation barriers physically separate field signal paths from internal backplane micro-logic, preventing transient surges from causing logic errors.
Fast Response Switching: Low input latency allows accurate detection of high-speed limit switches, optical encoders, and sensor pulses.
Real-Time LED Diagnostics: Individual channel LEDs display incoming signal states instantly, shortening electrical troubleshooting time during panel commissioning.
Flexible Wiring Formats: Compatible with both Sink (NPN) and Source (PNP) field wiring configurations for broad compatibility with sensor brands.
Robust Hardware Filtering: Built-in debounce filters eliminate contact bounce false triggers from mechanical relay contacts and switches.
Model Classification
SSAS21-DI: Standard 24V DC Discrete Digital Input Module.
SSAS21-DO: Discrete Digital Output Module (Relay/Transistor output interface).
SSAS21-AI: Precision Analog Input Module (4–20mA / 0–10V process inputs).
SSAS21-CPU: Central Processing Unit Module for the SSAS21 series architecture.
SMTB-DI: External DIN-Rail Digital Input Terminal Board (Used for external terminal routing).
Environmental Tolerance Conditions
Operating Temperature: 0°C to +55°C (32°F to 131°F)
Storage Temperature: -25°C to +70°C (-13°F to 158°F)
Operating Relative Humidity: 5% to 95% RH (Non-condensing)
Vibration Resistance: Conforms to IEC 60068-2-6 (10–57 Hz @ 0.075mm, 57–150 Hz @ 1.0g)
Shock Immunity: 15g peak acceleration, 11 ms duration (IEC 60068-2-27)
Enclosure Protection: IP20 (Must be installed in an IP54 or higher control cabinet)
Installation Method
Power Isolation: Shut off main power to the SSAS21 rack before inserting or removing the module.
Backplane Insertion: Align the rear guide rails of the SSAS21-DI module with the target slot on the SSAS21 base chassis. Press firmly until the module locks into the backplane connector.
Module Retention: Tighten top and bottom panel retention screws to secure the module against vibration.
Field Cable Connection: Attach the pre-wired terminal block to the front interface connector and secure terminal locking screws.
Operating Instructions
Field Wiring Selection: Ensure external 24V DC sensor power supply common (0V/V+) is correctly jumpered for Sink or Source configuration.
Signal Voltage Verification: Maintain input signal voltages within 18V DC to 28.8V DC; voltages below 11V DC may register as logic “0”.
Routine Maintenance: Periodically check terminal connections for tightness and clean dust accumulation from chassis ventilation slots.