LIGO PRO User Guide

Safety Information

⚠️ WARNING — Installation Safety
LIGO SP Fuel Level Sensor measures the accurate fuel level in fuel tanks; therefore the device installation process must be extremely accurate. Installation technicians should be well-trained by specialists or experts in this field before installing the device. Implement protection against electric shocks and electrical fires, labour safety and hygiene.

ℹ️ NOTICE — Required Tools & Accessories
List of installing tools is provided in the Installation section. List of accessories is provided in the Package Contents section.

Product Overview

LIGO Fuel Level Sensor is produced and developed by SOJI Electronics Joint Stock Company. The device is designed to measure the level of liquid fuels and other non-conductive liquids in vehicle tanks and stationary fuel storages, applicable in different fields. The measured values will be transformed into output signal in the form of Analog, Frequency, RS232, RS485 and transmitted to a connected external device.

Under particular conditions, the device can reach a high accuracy up to 99.5%. At present, on the market there are several lines of sensor using different technologies to measure fuel level such as: magnetically operated switches (reed switches), ultrasound wave (ultrasonic sensor), capacitive sensing (capacitive sensor). Among these, capacitive sensing technology is considered to have the highest accuracy and greatest lifespan.

Highlight Features:

• High accuracy up to 99.5%.
• Wide operating voltage range (only applicable to LIGO-SP-PRO with the voltage from 7.5 to 75 V).
• Inside isolation voltage up to 2500 V (only applicable to LIGO-SP-PRO).
• Can be optionally cut off or prolonged up to 6000 mm.
• Automatic recognition for new length after being cut.
• Wide operating temperature range from −40 °C to +85 °C.
• A filter protects the probe from dregs and water.
• IP67 waterproof standard.
• Interference filter and thermal error compensation system.
• Installation and configuration software on PC through a Connection Device.
• Quick installation, security seal.

Applications:

• Trucks, container cars, excavators, trains…
• Boats, barges.
• Electric generators.
• Industrial oil storage tanks and stationary storage tanks.
• Factories, industrial zones.
• Fuel storage tanks in agricultural machines and maritime transportation…

Package Contents

Figure 23. Sensor LIGO SP and all the accessories

No.	Description	Qty
1	LIGO Fuel Level Sensor. Standard lengths: 700, 1000, 1500 mm (for other customized lengths, please contact the manufacturer)	01
2	7 m cable	01
3	Gasoline-resistant rubber gasket	01
4	Oil filter	01
5	Anti-vibration spring	01
6	Fuse 2 A	01
7	Sealing cord	02
8	Rivet and screw M5 × 20 mm	04
9	Self-drilling screw M4.8 × 32 mm	04

Specifications

LIGO-SP

Parameter	AF	RS232	RS485
Standard length (L), mm	700, 1000, 1500 … up to 6000
Measuring error, %	± 0.5 %
Output signal	Analog (0…9 V), Frequency (500…2000 Hz)	RS232	RS485
Baud rate, bit/sec	9600	2400, 4800, 9600, 19200, 38400, 57600, 115200
Power supply (DC input voltage, V)	15–37	12–37	12–37
Maximum power consumption, mA	20
Ingress protection rating	IP67
Operating temperature, °C	−40…+85
Maximum allowed humidity level, %	100
Resolution, bit	12
Digital reading range — minimum level	Analog (0…8 V); Frequency (500…1500 Hz)	0	0
Digital reading range — maximum level	Analog (1…9 V); Frequency (1000…2000 Hz)	4095	4095
Average sampling period, s	0…255
Message interval, s	Continuous	1…60	1…60
Absolute error in temperature measurement, °C	± 2
Average service life, years	8

LIGO-SP-PRO

LIGO-SP-PRO product is designed for devices having wide input voltage (7–75 V); the voltage of the internal sensing printed circuit board isolated from outside is 2500 V. The internal temperature sensor has a very low error at < 0.6 °C. The product is designed to operate in extreme environments.

Parameter	AF	RS232	RS485
Standard length (L), mm	700, 1000, 1500 … up to 6000
Measuring error, %	± 0.5 %
Output signal	Analog (0…9 V), Frequency (500…2000 Hz)	RS232	RS485
Baud rate, bit/sec	9600	2400, 4800, 9600, 19200, 38400, 57600, 115200
Power supply (DC input voltage, V)	7–75 (2500 V internal isolated)
Maximum power consumption, mA	20
Ingress protection rating	IP67
Operating temperature, °C	−40…+85
Maximum allowed humidity level, %	100
Resolution, bit	12
Digital reading range — minimum level	Analog (0…8 V); Frequency (500…1500 Hz)	0	0
Digital reading range — maximum level	Analog (1…9 V); Frequency (1000…2000 Hz)	4095	4095
Average sampling time, s	0…255
Message interval, s	Continuous	1…60	1…60
Absolute error in temperature measurement, °C	± 0.6
Average service life, years	10

Installation

Tools Required

No.	Description	Qty
1	Bimetal core drill ø38 mm	1
2	Core drill shank	1
3	Metal drill ø7 mm & ø4 mm	1
4	Hacksaw	1
5	T-Spanner 8 mm Single Sided	1
6	Tap M5 with holder	1
7	Snap-seal for bolt/self-tapping screw	1
8	Laptop	1
9	DC power supply unit 12–24 V or battery 12 V	1
10	Measuring container	1
11	Fuel	1
12	Gauging container	1
13	USB to RS232 cable	1
14	Tape measure	1

Step 1: Selecting the Location to Install Sensor

Installation location should be as close as possible to the geometric center and placed at the deepest level of the tank.

Figure 1. Selecting the location to install sensor

When being installed, the sensor should not be in contact with reinforcement ribs inside the tank.

Figure 2. Installation of two sensors in one tank allows for significant reduction

Step 2: Drilling the Hole on Fuel Tank

Drill out the central bore by bimetal core drill ø38 mm:

Figure 3. Drilling the selected hole

Drill out four mounting holes according to the diagram:

Figure 4. Drill out four mounting holes

The mounting hole diameter depends on the tank material:

• ø4 mm — for metal tank with wall thickness over 3 mm (cut M5 self screw M4.8)

Figure 5.

• ø7 mm — for plastic and metal tank with wall thickness up to 3 mm (for rivets)

Figure 6. Rivet nut M5

Figure 7. Installing rivet nut if tank's wall is thinner than 3 mm

Step 3: Measuring the Tank Depth and Cutting Sensor's Measuring Probe

Figure 8. Measuring the tank depth

Cut the sensor's measuring probe so that its length is 25 mm less than the depth of the tank. Ensure that the shearing line is perpendicular to the sensor longitudinal axis.

Figure 9. Origin length (L) and length after cutting (Lm)

⚠️ CAUTION — Minimum Probe Length
Minimum allowable length of the measuring probe is 150 mm.

Step 4: Installing and Connecting

Apply oil-and-petrol resistant non-conductive sealant to the rubber gasket:

Figure 16. Applying the sealant to gasket

Put the sensor into the tank and fix:

• When fixing with rivets, use a rivet driver.
• When bolting, put on a seal (per bolt), a spacer and a spring washer.
• When fixing to plastic tanks with wall thickness over 3 mm, use vendor-furnished self-tapping screws and a seal (per self-tapping screw).

Figure 17. Put sensor into the tank

Connect the sensor to an external device using the 7 m cable.

RS232 / RS485

Figure 18. Wiring diagram of RS232 and RS485 output signals

Wire Colour	Description
Black	GND (Ground) (V−)
Yellow	RXD / B−
Blue	TXD / A+
Red	12–37 VDC, or 7.5–75 V for SP-PRO series

AF (Analog & Frequency)

Figure 19. Wiring diagram of Analog and Frequency output signals

Wire Colour	Description
Black	GND (Ground) (V−)
Yellow	Out (Analog / Frequency)
Red	15–37 VDC, or 7.5–75 V for SP-PRO series

• Connect the fuse holder to LIGO sensor power cable (brown wire) in close vicinity to the vehicle power supply circuit.
• Install the fuse in the fuse holder.

Step 5: Sealing

Install the bolt through a hole in the seal.

Figure 22. Sealing

Configuration

Connecting Configuration Tool

Preparation:

• Laptop or PC
• Power supply 12–24 VDC or battery 12 V
• USB to RS232 cable
• Configuration tool from SOJI ELECTRONICS (we recommend upgrading to the latest possible version)

Figure 10. Connecting USB to RS232 cable and configuration tool to laptop or PC

Installing USB to RS232 Driver

Install the driver for the USB to RS232 cable. After finishing, right-click and check to ensure the driver is installed successfully: Computer → Manage → Device Manager → Port (COM & LPT)

If the driver does not appear, please check the cable and cable driver.

Figure 11. Installing USB to RS232 driver successful

Installing Sensor Software Configuration

Visit our website: sojielectronics.com/document-download and download the setup file Setup Utility Program.

Figure 12. Sensor configuration tool

Parameters Descriptions:

• Load config: Load configurations from sensor to PC. Note: user must load configurations from sensor before changing configurations on PC.
• Save config: Save configurations from PC to sensor.
• Update firmware: Upgrade new firmware for sensor (visit www.sojielectronics.com for the latest firmware version).
• Set full: Set Full for maximum fuel level calibration.
• Set Empty: Set Empty for minimum fuel level calibration.
• Level Min: Configure LIGO SP-AF output voltage or frequency range according to the voltage or frequency range of the tracking device input.
• Level Max: Configure LIGO SP-AF output voltage or frequency range according to the voltage or frequency range of the tracking device input.
• Output type: Select voltage or frequency output (used only for AF sensor).
• Filter time: Set output signal processing time (0–255). Default is 60 seconds.
• Automatic transmission mode: Applied only for RS232/RS485 — defines sensor output message type:
  • Off — no automatic message transmission, sensor waits for tracking device request;
  • HEX — automatic message transmission in binary format (used by default);
  • ASCII — automatic message transmission in text format;
  • ASCII EXT — automatic message transmission in extended text format. Additional Prefix and Postfix configurable parameters are available for this mode to insert required header or ending of the message.
• Message interval: Time period the sensor automatically sends output message to the tracking device. Parameter value range is 1…255 seconds with 1 second step. Default value is 1 second.
• Actual length: The actual length of sensor probe.
• Address (0–254): Set the network address for the sensor. When several sensors are connected to one external device, they should have a unique network address.
• Parameter selection: Selection of output value type for sensor data. One of the following output value types available for RS232 and RS485 sensor:
  • Fuel level in standard (normalized) units (0…1000).
  • Fuel level in millimeters (mm), 0.1 mm step.
  • Fuel volume in liters (L), 0.1 L step.
  • Fuel volume in percentage (%), 0.4% step.
• Output:
  • OSC frequency: Initial measuring generator frequency (Hz).
  • Data output: Data output (0–4095).
  • Sensor message: Sensor working message. If sensor message is none, sensor works fine; otherwise malfunction codes are displayed — see Troubleshooting.
• Calibration Table: Used to record fuel tank calibration into the sensor internal memory. The table is filled out with the data achieved during fuel tank calibration procedure. The data is entered as a table of correspondence between measured fuel level value (Fuel level (uint) field) and fuel volume in the tank (Volume (L) field). Recommended number of table entries is 15. Max possible is 30 entries.
• Enable AutoCalib feature: Sensor automatically calibrates Min, Max levels after cutting. User does not need to reconfigure after cutting.

Min/Max Calibration

Set Empty level — Keep sensor apart from fuel and set Empty level.

Figure 13. Setting Empty level

Set Full level — Fill the measuring container with fuel. Immerse the sensor in the fuel to the full length of the measuring probe and set Full level.

Figure 14. Setting Full level

Calibration Table

1. Launch Sensor → Load Config → From Sensor → Calibration Table.

Figure 20. Calibration table

1. Pump fuel into the tank. The amount of pumped fuel depends on the tank's volume (at least 20 times of pumping).
2. After pumping, wait for a while (about 2 minutes) for the output data to be stable, then select "Add a row" and insert the actual pumped liters in the "liter" box. Input the data given by sensor into the "Data" box. User can click on the button to sync up data, or read data in the "Output" tab.
3. Repeat the above steps until the oil tank is full.

   Attention: It is recommended to write down the information on paper to compare with input data and avoid mistakes during the process.

4. After completing the above process, select "Volume (liter)" as the output data.

Figure 21. Parameter selection

Finally, click on the Sensor button at the top left corner → Save config → To sensor to save data for the sensor.

⚠️ CAUTION — Calibration Timing
The time between each pumping must be at least 2 minutes apart, or wait for measured values to be stable before the next pumping.

Quick Installation Without PC

This method is only applicable to configure Min and Max level.

Preparation before setting up:

The sensor's auto-recognition mode needs to be turned on by checking the "Enable AutoCalib Feature" box.

Figure 24. Turning on the auto-recognition mode before installing

External devices such as GPS tracking or Datalogger must have the software integrated with the configurator. The configuration is performed directly on the device.

Automatically setting up and configuring the sensor after cutting:

After measuring and cutting the sensor, remove iron filings and clean burrs between the tubes, then follow steps below:

1. Do not allow the sensor to contact oil.
2. Ensure 12–24 VDC stable power supply for the sensor.
3. Make sure the sensor is under stable condition within 30–60 s. The sensor will automatically recognise Min and Max level.
4. Cut the power and reboot. The sensor now recognizes new configurations.

Figure 25. Leave the sensor in the air, provide with a stable power supply in 30–60 s to configure "Min" level

⚠️ CAUTION — Auto-Calibration Limitation
In case of improper operation and the sensor cannot recognise properly the actual Min/Max level, user should reconfigure using a PC.

Operation

After successful installation and calibration, the sensor continuously measures fuel level and transmits data to the connected external device via the configured output:

• AF (Analog & Frequency) — continuous voltage (0–9 V) or frequency (500–2000 Hz) signal proportional to fuel level.
• RS232 / RS485 — digital messages at configured intervals (1…60 s), data range 0–4095.

The fuel level value can be reported in:

• Normalized units (0…1000)
• Millimeters (0.1 mm step)
• Liters (0.1 L step)
• Percentage (0.4% step)

Working messages and any malfunction codes are accessible via the configuration tool's Output → Sensor message panel — see Troubleshooting for code descriptions.

Troubleshooting

If the sensor message field shows a code other than empty, the sensor reports a malfunction. Code interpretations:

Sensor Message	Transcript of the Malfunction Code	Possible Solution
255 or 254	Calibration error	Check if the measuring probe actual size value is inserted correctly and (or) re-calibrate the sensor.
253	Short circuit in measuring probe tubes	Wash the measuring probe tubes with clean fuel, clean fuel tank of mud and water.
252	Calibration error	Check if the measuring probe actual size value is inserted correctly and (or) re-calibrate the sensor.
251	Hardware failure	Contact your supplier.
250	Calibration error	Check if the measuring probe actual size value is inserted correctly and (or) re-calibrate the sensor.

If problem persists, contact Support.

Maintenance

Installing Screen Filter

Screen filter is mounted on the measuring probe of sensor to protect measuring probe electrodes from mud and water. Using the filter extends significantly the faultless lifetime of the sensor.

Screen filter mounting order: Firstly put on fixator, then put on bottom stop and fix it with two side screws. Put the screen filter over the bottom stop and fasten it with the fixator locks.

Figure 15. Installing screen filter procedure

⚠️ WARNING — Warranty Notice
The manufacturer is not responsible for product availability in case of non-compliance with the requirements of this service manual, unauthorized service and repair; if the device has damage or traces of opening of the head's body, mechanical damage of the probe or the interface cable, as well as traces of corrosive acids, open flame, high voltage, lightning strikes or other natural factors.

Certification / Compliance

No certification or compliance information was provided in the source user manual (LIGO SP & SP-PRO User Manual 20.02.2020). Refer to Product Certification & Approvals for current certificate status.

Support / Contact

Channel	Detail
Company	SOJI ELECTRONICS JOINT STOCK COMPANY
Address	NO-04, LK-03 Ha Tri, Ha Cau, Ha Dong, Hanoi, Vietnam
Tel/Fax	+84 24 62 932 369
Email	contact@sojielectronics.com
Website	sojielectronics.com

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