The SCT-20 Series is a signal conditioning transmitter and indicator designed for weighing systems, offering a compact and versatile solution for various industrial applications. It functions as a weight indicator and transmitter suitable for Omega/DIN rail mounting, featuring a space-saving vertical shape.
Function Description:
The SCT-20 Series is primarily a weight transmitter that processes signals from load cells and provides various output options for integration into control systems. It displays gross weight on a six-digit semi-alphanumeric display (18 mm high, 7 segments) and is operated via a four-key keyboard. Key functions include zero setting, tare capture (net/gross switching), and access to setup menus.
The device supports both theoretical and weight-based calibration, allowing for precise adjustment of scale parameters such as maximum capacity, zero setting, and units of measure. It incorporates filtering capabilities to eliminate environmental noise, ensuring stable weight readings, with adjustable response times to suit different application needs.
For communication, the SCT-20 offers a wide range of serial and network protocols. It can transmit gross or net weight via an RS-485 serial port using Modbus RTU, ASCII bidirectional protocol, or continuous transmission. Optional modules extend its connectivity to DeviceNet™, PROFIBUS, PROFINET-IO, EtherNet/IP™, and Modbus/TCP, enabling seamless integration into various industrial automation networks.
The analog output option allows the device to transmit gross or net weight as an opto-isolated 16-bit analog signal (0-20 mA, 4-20 mA, 0-10V, 0-5V, ±10V, or ±5V). It also features three relay outputs for setpoint control and two opto-isolated digital inputs for external commands like remote zeroing or gross/net switching.
Important Technical Specifications:
- Power Supply: 12/24 VDC ± 10%; 5W
- Max Sensitivity of Usable Load Cells: ±7 mV/V
- Max Conversions per Second: 300/second
- Display: STN backlight transmissive LCD, 128 x 64 pixel resolution, 2.36 x 1.26 in (60 x 32 mm) viewing area. Seven-segment LED display with 0.3 in (8mm) character height.
- Keypad: 4-key membrane panel, tactile feel.
- Analog Output: Opto-isolated 16-bit (65535 divisions), configurable for 0-20 mA, 4-20 mA (max 300 ohm), 0-10 VDC, 0-5 VDC, ±10 VDC, ±5 VDC (min 10 kohm). Linearity <0.01% F.S.
- Relay Logic Outputs: 3 relays, max 115 VAC; 150 mA.
- Logic Inputs: 2 opto-isolated, 5-24 VDC PNP.
- Serial Ports: RS-485 (RS-232), Baud Rate: 2400, 4800, 9600, 19200, 38400, 115200.
- EtherNet/IP™ Port: RJ45 10Base-T or 100Base-TX (auto-sensing).
- PROFIBUS Port: Baud Rate up to 12 Mbit/s, Addresses 1-99.
- DeviceNet™ Port: Baud Rate 125kbit/s, 250kbit/s, 500kbit/s, Addresses 1-63.
- Modbus/TCP Port: RJ45 10Base-TX (auto-sensing).
- Number of Load Cells: Max 8 (350 ohm); 5 VDC/ 120 mA supply.
- A/D Converter: 24 bit (16,000,000 points).
- Measurement Range: ±39 mV.
- Enclosure Dimensions (W x H x D): 0.98 x 4.52 x 4.72 in (25 x 115 x 120 mm).
- Environmental: Operating Temperature -4°F to 140°F (-20°C to 60°C), Storage Temperature -22°F to 176°F (-30°C to 80°C), Humidity 85% (Non Condensing).
- Certifications: cULus Recognized, FCC, CE, UKCA.
Usage Features:
- Easy Configuration: The device offers a structured menu for configuring scale parameters, communication settings, and input/output functions. This includes calibration, filter settings, zero parameters, serial communication, DeviceNet™, PROFIBUS, EtherNet/IP™, Modbus/TCP, and analog output settings.
- Calibration Flexibility: Supports theoretical calibration by setting load cell rated values (full scale, sensitivity, divisions) and weight (span) calibration using actual test weights.
- Zero Setting: Allows for quick zeroing of the scale to compensate for deadload or environmental variations.
- Unit of Measure Selection: Configurable units of measure (kg, g, lb, tons, Newton, liters, bar, atmospheres, pieces, Newton Meter, Kilogram Meter).
- Setpoint Programming: Enables programming of up to three setpoints with hysteresis for relay switching based on weight thresholds.
- Menu Locking: Features a menu locking mechanism to prevent unauthorized access to configuration settings, with options for temporary unlocking.
- Diagnostic Tools: Includes a "Test" menu for checking input/output status, analog output, and load cell millivolt signals, aiding in troubleshooting.
- Alarms: Provides various alarm indications on the display (e.g., "Er-CEL" for load cell error, "Er OL" for overload, "Er Ad" for internal converter failure) and through communication protocols, with associated relay actions.
Maintenance Features:
- Load Cell Testing: Detailed procedures for load cell resistance and voltage measurement using a digital multimeter help identify issues such as moisture infiltration, incorrect resistance values, or signal increments.
- Grounding Recommendations: Emphasizes the importance of proper grounding for the weighed structure to prevent damage to load cells and the transmitter from electrostatic charges.
- Firmware Updates: The manual refers to accessing the most current version of publications, software, firmware, and product updates on the Rice Lake website.
- Technical Training: Rice Lake Weighing Systems offers technical training seminars for users to enhance their understanding and operation of the device.
- Customer Support: Important notes throughout the manual direct users to contact Rice Lake Customer Support for assistance if specific conditions or tests are not met.
- EEPROM Storage: Setpoints and hysteresis values can be saved permanently to EEPROM memory using a specific command, ensuring they are retained after power-off.
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