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LC-51K

Weighing Instruments

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LC-51K

Digital Load Cell Controller

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The LC-51K Digital Load Cell Controller is a high-precision industrial weighing controller designed to automate and manage load cell based systems. With ±0.05 percent full-scale accuracy, it ensures reliable performance in critical weighing applications. It features a bright 5-digit red LED display, RS485 Modbus RTU communication, and two relay outputs for process control. On-site calibration, password protection, and NV RAM memory ensure secure and stable operation. Compact and panel mountable, the LC-51K is ideal for industrial automation and advanced weighing control systems.

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Product Type

Digital Load Cell Controller

Usage

Industrial Automation, Material Testing, Check weighing, Hopper & Batching Systems, Silo & Tank Weighing

Material

Mild Steel Chasis with ABS cover

Output

RS485, Modbus RTU, Relay Output

Theory

Load Cell Controller

Calibration

Calibration can be done through setting via keypad

  • The LC-51K Load Cell Controller is ideal for industrial weighing and automation applications such as:
  • Batching & Mixing: Automatically stopping the flow of material once a specific weight is reached in a hopper.
  • Level Control: Monitoring the contents of silos or tanks to prevent overfilling or running dry.
  • Check weighing: Sorting products on a conveyor belt based on whether they meet a target weight range.
  • Safety Overload Protection: Disabling cranes or hoists if they attempt to lift a load exceeding their rated capacity.
Indication

5-digit Red LED display with a height of 12.5mm.

Indication Accuracy

0.05% of full scale.

Zeroing

Full-range push-button zero key provided on the front panel.

Input Type

Specifically designed for Load Cell signals.

Configuration

On-site calibration for range, resolution, decimal point, and zero shift.

Security

Password protection for all calibration and configuration settings.

Digital Output

RS 485 MODBUS RTU PROTOCOL.

Control Output

2 Relay Outputs (Normally Open) with settable control actions.

Memory

Programs are stored in NV RAM, ensuring data retention during power failure.

Power Supply

24VDC

Power Consumption

4 VA.

Terminals

Phoenix-type terminals suitable for up to 1.5 mm2 cable

Ambient Temperature

 10 to 50°C.

Weight

Approximately 300 grams.

Chassis Construction

Mild Steel (MS) chassis with an ABS cover

Overall Bezel Size

96 mm (W) x 48 mm (H)

Panel Cut-Out

92 mm (W) x 46 mm (H) with a depth of 125 mm

  • Signal Processing: It converts the millivolt signals from a load cell into a high-resolution digital readout, often with an accuracy as precise as 0.05% of the full scale.
  • Programmable Logic: Controllers like the LC-51K feature a programmable memory (NV RAM) that retains settings during power failures.
  • Control Outputs: They typically include multiple relay outputs (e.g., Normally Open) used to start or stop pumps, motors, or valves based on set weight limits.
  • Industrial Connectivity: Integration into plant-wide systems is achieved through protocols like RS 485 MODBUS RTU, allowing real-time data sharing with PLCs and SCADA systems

Industries

Weighing Scale
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FAQs

frequently asked questions

01. What is the fundamental role of a Load Indicator in a weighing system?

A Load Indicator (or Digital Weight Indicator) is the primary user interface and digital core of the weighing system. Its main roles are:

  • > Power Supply: It provides the stable excitation voltage (power) to the load cell.
  • > Signal Conversion: It receives the raw, micro-voltage (mV) signal from the load cell, amplifies it, and converts it into a digital value.
  • > Display: It displays the final calculated weight in a readable format (kg, T, N) to the operator.
  • > Calibration: It stores the system’s calibration parameters (zero, span, decimal points, capacity).
  • > Communication: It communicates with devices such as HMI, PLC, PC, other devices via modbus RTU RS-485.
02. How does a Load Controller differ from a basic Load Indicator?

A Load Controller (or Process Controller) is essentially an indicator with additional control functionality used in automation:

  • > Indicator: It performs all the basic functions of a standard indicator (display, power, signal conversion).
  • > Control Logic: It contains built-in software or programming for specific applications like batching, filling, mixing, or checkweighing.
  • > Outputs: It features discrete I/O (Input/Output) relays or ports that can be used to control external devices (e.g., stopping a conveyor, opening a valve, or triggering an alarm) based on weight set points.
03. What is a Load Cell Amplifier (or Transmitter), and when is it necessary?

A Load Cell Amplifier (or Transmitter) is a specialized device used to prepare the load cell signal for communication with industrial controllers like PLCs (Programmable Logic Controllers).6

  • > Function: It takes the tiny mV signal and converts it into a standard, robust industrial signal, most commonly 4-20mA or 0-10VDC.
  • > Necessity: Standard industrial controllers (PLCs) cannot directly read the load cell’s raw mVoutput. The amplifier makes the signal less susceptible to electrical noise and voltage drop over long distances, ensuring the PLC receives an accurate, proportional weight reading.
04. Why is the 4-20mA signal commonly preferred in industrial applications?

The 4-20mA current loop is the most robust standard for transmitting analog signals in harsh industrial environments for two key reasons:

  • > Noise Immunity: Current signals are far less susceptible to electromagnetic interference (noise) over long cable runs than voltage signals.
  • > Live Zero: The 4mA value represents the zero output (unloaded state). If the signal drops to 0mA (or close to it), the system immediately detects a broken wire or power failure, providing a built-in error detection mechanism.
05. How do multiple load cells connect to a single indicator/controller?

When a system uses multiple load cells (e.g., a four-load cell tank system), they are connected using a Junction Box (J-Box).

  1. Wiring: The cables from all individual load cells run into the J-Box.
  2. Trimming: The J-Box contains terminal blocks and typically trimming resistors to electronically adjust the output of each load cell (called corner trimming or balance adjustment).
  3. Summation: The signals are electrically summed together within the J-Box.
  4. Single Output: A single main cable then runs from the J-Box to the Indicator or Controller, providing one combined weight signal.