Laumas TLM8 weighing transmitter

Laumas TLM8 Eight Channel Weighing Transmitter Complete Application Guide

Product Overview and Technical Positioning

The Laumas TLM8 series is a high-performance eight channel independent weighing transmitter designed for industrial applications that require simultaneous monitoring of multiple weighing sensors. Unlike traditional single channel or multi-channel parallel connection through junction boxes, TLM8 provides an independent signal reading channel for each weighing sensor and can display the total weight on the local display screen. This design fundamentally solves the problem of traditional analog junction box balancing being cumbersome and prone to drift.

The TLM8 has a compact size of only 148 × 92 × 60 mm, supporting Omega rail or DIN rail installation, and can also be installed in junction boxes according to requirements. The device is equipped with a backlit LCD graphic display screen (128 × 64 pixels, visible area 60 × 32 mm) and a 5-key keyboard for intuitive operation. All wiring terminals are pluggable screw terminals for easy on-site maintenance and replacement.

This device can be configured and managed through the free PC software Instrument Manager, greatly reducing the debugging threshold.

Hardware interface and fieldbus options

The housing of TLM8 offers multiple protection level options: standard type, IP67 polycarbonate enclosure (provided on demand), and IP68/IP69K AISI 304 stainless steel enclosure (provided on demand), which can adapt to various occasions from dry control cabinets to humid, high-pressure flushing environments.

Core I/O resources:

8 independent weighing sensor inputs: Each channel can be individually connected to an analog strain gauge sensor.

5-way relay output: can be controlled by setpoints or through communication protocols, used for alarm, ingredient valve control, etc.

3-channel optoelectronic isolated PNP digital input: Status can be read through serial port or fieldbus, used for external startup, reset and other commands.

1 RS485 serial port: supports Modbus RTU, ASCII Laumas protocol, or continuous unidirectional transmission mode.

Rich fieldbus options (differentiated by model suffix):

Model Code Communication Interface Description

TLM8 RS485 (Basic Edition) only serial port

TLM8CANOPENED CANopen slave, baud rate 10-1000 kbit/s

TLM8DEVICENETD DeviceNet slave, baud rate 125/250/500 kbit/s

TLM8CCLINKD CC Link remote device station, occupying 3 stations, with baud rates ranging from 156 kbit/s to 10 Mbit/s

TLM8PROFIBUSD PROFIBUS DP slave, maximum 12 Mbit/s

TLM8MODBUSTCPD Modbus/TCP (single RJ45) 10/100 Mbit/s adaptive

TLM8ETHTCPD Ethernet TCP/IP (single RJ45) supports web browser access (web app)

TLM8ETHEIPND EtherNet/IP (Dual RJ45) Adapter

TLM8PROFINETIOD PROFINET IO (Dual RJ45) Device, 100 Mbit/s

TLM8EtherCATD EtherCAT (dual RJ45) slave station

TLM8POWERLINKD POWERLINK (dual RJ45) slave station

TLM8SERCOSD SERCOS III (dual RJ45) slave station

All of the above bus versions also retain RS485 serial ports, which can be used to connect to PCs, remote displays, or inclinometers simultaneously.

Analog output options (bus independent):

16 bit analog output, programmable as:

Current: 0-20 mA or 4-20 mA (maximum load 400 Ω)

Voltage: 0-10 V or 0-5 V (minimum load 2 k Ω)

This analog output is typically used to transmit the total weight or individual channel weight values to PLCs or recorders without a fieldbus.

The core advantage of eight channel independent reading

3.1 Pain points of traditional junction box methods

In a conventional multi-sensor weighing system, multiple sensors are connected in parallel through a junction box and a potentiometer (fine adjustment resistor) is used to adjust the angle difference/balance. This method has the following issues:

Adjustment is cumbersome: it requires multiple loading of weights and repeated rotation of potentiometers, which is time-consuming and relies on experience.

Long term drift: The potentiometer contacts are affected by vibration and oxidation, and the equilibrium point will change over time, causing weighing errors.

Diagnostic difficulty: unable to individually view the output signals of each sensor, unable to quickly locate faulty sensors.

3.2 TLM8's digital equalization function

TLM8 provides independent reading channels for each sensor without the need for physical junction boxes. Its digital balancing function is achieved through software algorithms:

Record the zero output of each channel in an unloaded state.

Load a standard weight at a calibration point (usually a part of the full range) and record the millivolt signal increment for each channel.

The system automatically calculates the gain correction coefficient for each channel to ensure that all channels have consistent responses to the same weight.

This process only requires one loading, and the correction factor is stored in non-volatile memory, with no mechanical drift and far better long-term stability than analog potentiometers. At the same time, users can view the real-time signal (mV) of each channel at any time through the display screen or software, and intuitively judge whether the sensor is damaged or under abnormal force.