Independent digital probe design ensures high measurement accuracy and stable test data Dual RS485 communication interfaces/MODBUS protocol, compatible with PLC, PC, etc. Ultra-small digital probe, super simple to use and install

The LS501 Transmittance Digital Probe is an intelligent sensor designed to measure the transmittance or optical density of transparent materials. It is suitable for real-time monitoring in various industrial scenarios. Equipped with dual RS485 interfaces and MODBUS protocol, it seamlessly integrates with PLCs, and PCs for real-time data acquisition. Applications include online production monitoring, quality inspection for glass, window films, and liquid transmittance analysis.

The probe measures transmittance by comparing incident light intensity with transmitted light intensity through the tested material, calculated as a percentage ratio.

LS501 digital probe to test liquid

LS501 digital probe test film glass

LS501 digital probe test solar film

Features

Stable Digital Probe Design

Integrated digital signal processing ensures interference-free, high-precision transmittance/OD output.

RS485/MODBUS Compatibility

Dual RS485 interfaces with MODBUS protocol enable seamless automation integration with PLCs, HMIs, and PCs.

Compact & Easy Installation

Split design (light source + detector) with mounting brackets; simplified 6-wire connection.

Magnetic probe, easy to align

There is a magnetic attraction between the light source probe and the receiving probe, making alignment convenient.

Metrology Certification

Accuracy certified by national metrology institutes.

Optional Accessories

(Note: RS232 converter, USB converter are not standard and can be purchased as needed.)

1. RS232/RS485 Converter

Used for communication protocol debugging.

2. USB Converter

For connecting RS485 to USB for computer data reading.

Temperature Compensation

Ensures stable performance in high-temperature environments.

Installation

Schematic diagram of star wiring

Star Wiring

Linear Wiring Appearance

Communication Settings

1. Station Address

Default MODBUS address: 1 (configurable range: 1–247).

2. Baud Rate

Default: 19200bps (options: 4800/9600/19200/38400).

3. Protocol

Full MODBUS support; refer to Transmittance Digital Probe Communication Protocol for command details.

Product Parameters

Measurement Wavelength	Default: 380–760 nm；Customizable: 850 nm / 530 nm
Measurement Spot	Ø 8mm
Transmittance Accuracy	±1% (for uniform colorless materials)
Transmittance Resolution	0.005%
Optical Density Range	0.00 OD - 6.00 OD
Optical Density Resolution	0.01 for 0.00 - 3.00 OD；0.05 for 3.00 - 5.00 OD；0.15 for 5.00 - 6.00 OD
Test Sample Thickness	<100mm
Operating Temperature	-10℃ to 60℃
Storage Temperature	-20℃ to 70℃
Humidity	<85% (non-condensing)
Data Refresh Rate	300ms (normal mode) /100ms (fast mode)
Communication	Dual RS485
Protocol	MODBUS
Power Supply	7.5V–9V DC
Current	50mA
Power Consumption	375mW
Light Source Probe	83.5*38*50(mm)
Receiver Probe	79.95*38*50(mm)
Cable Length from Junction Box to Probe	1 m (customizable)
Cable Length from Junction Box to PLCs or HMIs	1 m (customizable)