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FAQ#119 - Why can't I connect the BRAIN reel to my mobile phone/tablet? Have I connected correctly my BRAIN measuring system?

Make sure that ALL the following steps are checked:
1. The batteries of the mobile phone/tablet and the BRAIN system are charged
2. You have installed the latest version of the BRAIN APP (check the Google Play Store or Apple Store)
3. The version of the mobile phone/tablet's operating system is Android 7 or higher, or iOS 11 or higher
4. The Bluetooth version of the mobile phone/tablet is 4.2 or higher
5. Only for Android mobile phones/tablets:
• in the Android settings, the BRAIN APP has all the permissions (storage, geolocation)
• as first thing, pair the mobile phone/tablet to the BRAIN, from the Android settings, as described in the BRAIN user manual
• if the system keyboard does not allow the correct decimal separator to be entered, install the "Gboard" app which allows the standard Google keyboard to be used
6. The measuring probe is correctly connected to the BRAIN reel connector, as described in the user manual
7. Once the measuring probe (inclinometer, spiral meter or T-REX) has been connected, start a measurement or checking the system with the appropriate button of the app: the led on the BRAIN reel must never be red. A red LED means that the BRAIN reel does not see the measuring probe connected correctly.

T-REX Incremental Extensometer
B.R.A.IN MEMS inclinometer systems
B.R.A.IN App

FAQ#111 - Why I cannot read correctly my 4-20mA current loop gauge?

It could be a problem connected to the power supply given by the readout or logger. When the power supply is in the current loop (2-wire gauge) it is necessary to consider the effect of voltage drop across the shunt resistor on the voltage applied to the gauge.

For example, suppose a 4-20mA gauge requires at least 12 V to operate correctly and the readout powered with 16 V. The voltage the gauge sees is the voltage supplied by the readout minus the voltage drop in the rest of the current loop. At 20 mA output, the voltage drop across the commonly used 100 ohm resistor is 2 V.

When the voltage supplied by the readout is 16 V, this leaves 14 V for the gauge and everything is fine.
However, if the readout is powered with less than 14 V, at 20 mA current it will leave less than 12 V for the gauge. In this case, the output of the transmitter may be in error.

Wire Deformeters
MEMS In-place Inclinometers
Wire Crackmeters
Multipoint settlement gauges
MPBX - Multipoint Borehole Extensometers
MEXID Miniaturized MPBX
Fixed Extensometers
Electric Anchor Load Cells
Earth Pressure Cells
Electro-hydraulic Load Cells for Steel Linings and Struts
Crackmeters and Jointmeters
Mini OMNIAlog datalogger
Flat Jack Testing Accessories
Solid Resistive Load Cells for Pile Testing
H-Level - Liquid Level Systems
Convergence extensometer (DISCONTINUED)
Piezo-Resistive piezometers
Vented pressure transducers
Removable pressure transducers
Titanium piezometers
Drive-in piezometers
MEMS Analogue Tilt Meters

FAQ#110 - What's the purpose of the linear and polynomial factors written in the Calibration Reports?

Utilize the Linear Sensitivity Factors (A, B) and Ploynomial Sensitivity Factors (A, B, C, D) of the Calibration Reports permit to obtain readings in engineerig units with a maximum error as for the Calibration Report.

In the case of analogue gauges, the factors shall be applied on the electrical readings (i.e. mA, mV, digit, etc...)

In the case of digital gauges in "Legacy mode" (digital gauges with FW version 0.X, 1.X, 2.X or 3.X), the factors shall be applied on the output in engineering units (i.e. sin angle, kPa, etc...)

In the case of digital gauges in "Normal Mode" (digital gauges with FW version 3 or higher), the factors are already applied inside the gauge, so the Sensitivity Factors shall not be utilized with these instruments.
NOTE: all the new digital gauges are in "Normal mode".

For more information regarding SISGEO Calibration Report, refer to the following video

For more information on "how to use" the Sensitivity Factors with analogue gauges and with digital gauges in Legacy Mode, refer to the instruments manuals or to the following document:



MD-Profile system

FAQ#094 - Which are the available powering modes for SISGEO digital sensors?


All SISGEO digital gauges can be settled in two different powering mode:

  • ALWAYS ON: all digital sensors switched on together. Faster solution, but high power consumption. The system will take about 1 second to read each gauge.
  • TIMED: the sensors are powered and switched-on one by one. Reading of the chain take more time than "always on", but the power consumption is lower. In this case the system will take about 3 seconds to read each gauge.

The STANDARD powering mode is ALWAYS ON, so unless otherwise requested by the Customer, the sensors are settled as default in ALWAYS ON.





DEX and DEX-S 3D extensometer
MEMS In-place Inclinometers
Tilt Beam (TB) sensors
D-Tiltmeter - Digital MEMS Tiltmeters
H-Level - Liquid Level Systems
BH-Profile in-place Inclinometers
MD-Profile system

FAQ#077 - Which are the maximum cable lengths from instrument to datalogger?


The cable lengths depend from many factors, first of all installation and cable protections (screen, earth, etc...). Assuming that instruments are installed in a workmanlike, for the maximum cable lengths should be followed the next suggestions:


ANALOGUE INSTRUMENTS: see both documents:

Cable length guide line with internal multiplexers
Cable length guide line with external multiplexers




MD-Profile system

FAQ#073 - Which is the maximum number of digitized sensors (RS-485, Modbus), the maximum number of chains and the maximum length of cable in a RS-485 network?

Last update: October 2021

All the SISGEO digitized sensors utilize a RS485 interface with Modbus protocol.

1.The maximum number of digitized sensors in a RS-485 network are 247 (theoretical)

2.The maximum number of digitized sensors chains that is possible to connect to Modbus master unit (as OMNIAlog or miniOMNIAlog) are 4.

3. About the maximum number of sensors in a chain and lengths, please follow the next tables:

Always ON Digital gauges

TIMED digital instruments

NOTE: The sum of “A” and “C” lengths can’t exceed 1000m. The compliance of points A and B, avoids the excessive voltage drop on the RS-485 line and guarantees the correct RS-485 network operation.



RDS Railway Deformation System
OMNIAlog Datalogger
Digital MEMS Inclinometer System (DISCONTINUED)
MEMS In-place Inclinometers
Tilt Beam (TB) sensors
D-Tiltmeter - Digital MEMS Tiltmeters
Mini OMNIAlog datalogger
H-Level - Liquid Level Systems
BH-Profile in-place Inclinometers
Horizontal In Place Inclinometers
MD-Profile system