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.

3.3 Load distribution analysis and backup archiving

TLM8 provides a graphical load distribution display interface that allows real-time viewing of the force ratios of 8 channels. This function is particularly important in situations where uniform force is required, such as material tanks, hoppers, and platform scales - engineers can quickly detect that a support point is suspended or overloaded, preventing structural damage.

The load distribution data of all channels can be regularly archived, queried, and printed for quality traceability.

Advanced diagnostic and maintenance functions

4.1 Independent channel diagnosis

Each weighing sensor input is equipped with a dedicated diagnostic function, which can be selected according to the system type:

Load automatic diagnosis: Automatically detect whether the sensor signal is reasonable during the loading process, and determine whether there is a wire break, short circuit, or signal out of range.

Zero point automatic diagnosis: detect whether the zero drift exceeds the allowable range during no-load operation, and determine whether the sensor is experiencing creep or abnormal temperature drift.

The diagnostic results can be directly displayed on the local display screen or sent to the PLC or upper computer through a communication interface.

4.2 Event Archiving

TLM8 automatically records the last 50 important events, including:

Zero point setting/calibration

Digital Balance Operation

Alarm triggered/restored

Tare (peeling) operation

All events can be stored, queried, and printed, providing objective evidence for quality management systems such as ISO 9001.

4.3 Tilt angle compensation (optional function, requires external inclinometer)

For weighing systems installed on mobile devices or non level ground, TLM8 can accept inclinometer signals (connected via RS485) and dynamically compensate for weight within a compensation range of ± 10 degrees. Even if the scale body is tilted, it can still output accurate weight values. This compensation also applies to legal for trade certification.

Weighing function and ingredient control program

5.1 Core weighing function

Theoretical calibration and physical calibration: Sensor parameters can be input through the keyboard for theoretical calibration, or standard weights can be used for physical calibration. It supports up to 8 points of linearization, significantly improving the accuracy of nonlinear sensors.

Digital filtering: adjustable filtering depth, effectively suppressing weight fluctuations caused by vibration and mechanical impact.

Stable weight condition judgment: The allowable fluctuation range and time window can be defined, and the "stable" flag can be output.

Standard weighing functions include automatic zeroing, zero tracking, semi-automatic skinning, preset skinning, and semi-automatic zeroing upon startup.

5.2 Single product ingredient (batch) program

TLM8 has built-in control logic specifically designed for single product ingredients, allowing for simple quantitative feeding control without the need for an external PLC. Main features:

Formula can be set (target value, fast/slow addition switching point, drop value, etc.).

Automatic drop calculation: Automatically adjust the lead time after each ingredient is added to improve batch consistency.

Tolerance error control: Over tolerance alarm and stop.

Fine blending mode: High precision micro replenishment can be achieved through slow feeding or tapping function.

Consumption storage: Record the actual discharge amount of each ingredient for easy material inventory management.

Ingredient data printing: Print ingredient records through RS232 (direct connection) or RS485 (external printer).

External startup: Ingredients can be started through external digital input or fieldbus commands.

Automatically peel at startup: Ensure that the measurement starts from the container tare weight each time.

This program is very suitable for applications such as small-scale ingredient systems, color masterbatch addition, animal feed distribution, etc., and can significantly reduce the requirements for PLC programming.

Legal for Trade certification version

For applications that require trade settlement, TLM8 can provide a certified version (to be specified at the time of ordering). The certified version has the following characteristics:

Parameter protection: Key measurement parameters (such as calibration coefficients and angle difference coefficients) are protected by passwords, hardware switches, or fieldbus write protection to prevent unauthorized modifications.

Weight subdivision display: supports 1/10E division value display.

Three operating modes: single interval, multiple ranges, and multi interval, suitable for different accuracy requirements.

Net weight/tare zero tracking.

Calibration: requires authorization or physical sealing.

Alibi memory (optional): records the raw data of all weighing transactions, meeting the requirements of weighing regulations for data storage.

Communication and System Integration

7.1 RS485 network

The RS485 interface of TLM8 supports up to 32 instruments to be connected to the same bus (without repeaters); If a repeater is used, it can reach up to 99 units. The protocol is Modbus RTU or Laumas ASCII and can communicate with the following devices:

Laumas W series weight display (via dedicated protocol)

PC or PLC (as Modbus slave)

Remote monitor, printer, inclinometer (via RS485)

Special feature: RS485 and RS232 can be directly connected without the need for a level converter, simplifying integration with older serial devices.

7.2 Fieldbus Integration

When selecting models with bus suffixes, TLM8 can serve as a slave/adapter/device for the following networks:

PROFIBUS DP: Standard industrial fieldbus widely used in PLC systems such as Siemens.

EtherCAT: High speed real-time Ethernet, suitable for motion control and high-speed weighing.

EtherNet/IP and PROFINET IO: used respectively for industrial Ethernet environments of brands such as Rockwell and Siemens.

CC Link: Mitsubishi Electric led fieldbus, commonly seen in Asia.

CANopen/DeviceNet: Suitable for in vehicle or distributed I/O systems.

Modbus/TCP: a universal Ethernet protocol that can communicate directly with SCADA.

Ethernet TCP/IP: Supports WEB APP integration software, which can be remotely monitored, configured, and diagnosed through a browser without the need to install a client.

7.3 Data content transmitted through the bus

Through fieldbus or RS485 (Modbus RTU), TLM8 can provide:

The raw millivolt signal value of each channel (unfiltered calculated value) - for PLC to perform weight calculation (zero point, tare weight, linearization) on its own.

The percentage of load distribution for each channel (% of total).

Total weight, weight of each channel (calibrated internally).

Relay output status and digital input status.

Diagnostic results (abnormal sensor indicators).

The status of the ingredient program (feeding in progress, completed, out of tolerance, etc.).

This flexible data granularity makes TLM8 not only an independent weighing instrument, but also an intelligent weighing sensor front-end that can implement complex algorithms in high-end PLCs or PCs.

Suggestions for Installation and Configuration Practice

8.1 Installation precautions

Power supply: TLM8 requires a stable 24V DC power supply. It is recommended to install an isolated power supply or filter to avoid coupling with interference sources such as frequency converters.

Sensor wiring: Use qualified 6-wire (with sense) or 4-wire weighing cables, with the shielding layer grounded at a single point on the instrument end. Each channel is independently wired to avoid mutual interference.

Relay output: When controlling AC contactors, RC absorption circuits or varistors must be connected in parallel at both ends of the coil to prevent reverse electromotive force from damaging the contacts.

Digital input: When external passive contacts or NPN/PNP signals are connected, please note that TLM8 is PNP type (high level effective), with the common terminal connected to 0V.

8.2 Configuring with Instrument Manager software

Recommend using the free Instrument Manager software provided by Laumas for initial setup:

Connect the USB-RS485 converter of the PC to the RS485 port of TLM8.

Scan the device and select the corresponding model.

Set the sensor parameters for each channel (sensitivity mV/V, range, etc.).

Perform digital balancing: Enter the mechanical position and weight of each channel in sequence according to the software wizard.

Configure analog output, relay settings, bus communication parameters (station address, baud rate, etc.).

8.3 Typical problem troubleshooting during on-site debugging

Possible causes and solutions for the phenomenon

A certain channel displays "abnormal" or no weight change. If the sensor is disconnected, has poor contact, or is damaged, enter the "Load Unit Input Test" menu to check if the mV signal of the channel is normal; Check the wiring terminals

Unstable total weight, large mechanical vibration, low filtering coefficient, and poor grounding increase the depth of digital filtering; Check the shielding grounding; Enable 'Stable Weight Condition' in the software

Bus communication failure with inconsistent baud rate, checksum, and station address; The terminal resistance has not been confirmed to be consistent with the parameters of TLM8 and the main station; Add 120 Ω terminal resistors at the beginning and end of RS485

Frequent ingredient deviation and inaccurate drop setting, as well as automatic drop learning function enabled for changes in material fluidity; Adjust the fast/slow add switching point

After calibration, the weighing non-linear sensor itself is non-linear or unevenly loaded during installation, and 8-point linearization calibration is used; Check the installation level of the sensor and rebalance it if necessary

Examples of application scenarios

Large tank weighing (3-8 support points)

Connect each sensor using TLM8 and output the total weight to PLC (PROFIBUS or EtherNet/IP) after digital balancing. At the same time, use the load distribution map to monitor whether each support point is empty.

Multi component batching system

Each TLM8 controls 1-2 sensors at a batching station, independently completing batch feeding using the built-in single product batching program. The PLC is only responsible for starting and collecting completion signals, greatly simplifying the program.

Dynamic tilt compensation platform

The scale installed on forklifts or mobile hoppers, combined with an inclinometer, TLM8 corrects weight errors caused by tilting in real time to ensure the accuracy of weighing during movement, and supports trade settlement certification.

IoT cloud connection

TLM8 is connected to the IoT gateway (or models with Ethernet TCP/IP) via RS485, and uploads the load distribution, total weight, and alarm events of each channel to the cloud for remote operation and predictive maintenance.