LTR114 Universal high-precision ADC module with sequential commutation of channels

Universal high-precision ADC module with sequential commutation of channels
  • Software-controlled function of null-offset and conversion scale auto-calibration
  • Multi-module synchronization of data acquisition by the principle of "master-slaves"
  • Separate measuring channel for DS18S20 temperature sensor
  • Software-controlled service function for checking the interruption or short circuit of external signal lines

LTR114 is designed for precision digitization of signals with a maximum total ADC sample rate up to 4 kHz in a wide range of voltages – from millivolt signals to 10-volt ones, as well as to measure the resistances of single tenso- and thermo-resistors (resistance thermometers) and potentiometric sensors. In particular, LTR114 will be of interest for low-temperature thermistor measurements, since with LTR114 commutation of the sensor supply current, the power dissipation per thermistor will be N times less (where N is the number of switched channels).

The "common wire" circuits of all voltage sources should be connected to the AGND circuit of the module.

LTR114 is adapted to work not only with closely located signal sources, but also spaced by tens of meters.

Voltage measurement mode

Number of channels 16 differential with serial switching
Resolution 24 bits
Input signal measuring sub-ranges ±10 V; ±2 V; ±0,4 V 
(set independently for each channel)
Maximum sampling rate 4 kHz (total for all channels polled)
Input resistance for single-channel input more than 1 GOhm (when ON)
Maximum permissible voltages at analog inputs (input protection) ±15 V
Conversion frequency, Hz Limits of the permissible basic relative error of DC voltage measurements, %, in the "Permanent calibration" operating mode, in the measurement subrange:
0,4 V 2 V 10 V
From 5 to 1000
From 1000 to 4000
Conversion frequency, Hz Limits of the permissible basic relative error of DC voltage measurements, %, in the "Initial calibration" operating mode, in the measurement subrange:
0,4 V 2 V 10 V
From 5 to 1000
From 1000 to 4000

Note: XК is the final value of the set measurement subband, V; X - the value by LTR114, V

Resistance measurement mode

Up to 8 channels can act as a switched current source for a 4-wire resistance measurement circuit with the use of an alternative programmable configuration for the contacts of input connector.

Number of resistance measuring channels 8
Measurement scheme 4-wire
Resolution 24 bits
Resistance measurement ranges 0 ... ..400 Ohm (at the current of 1.0 mA)
0 ... ..1200 Ohm (at the current of 0.33 mA)
0 ... ..4000 Ohm (at the current of 0.1 mA)
The maximum sampling frequency for the resistance measurement mode 4 kHz (normal measurement mode at constant current)
2 kHz (measurement mode at alternating current)
Conversion frequency Limits of the permissible basic relative error of measurements of resistance to a direct current, %, at the operating mode
«Permanent auto calibration» «Initial auto calibration»
5 Hz
From 5 to 2000 Hz
4000 Hz: in subbands
400; 1200 Ohm
4000 Hz: in the sub-band
4000 Ohm

Note: XК is the final value of the set measurement subband, Ohm; X - the value by LTR114, Ohm

Different combination of the number of voltage/resistance measurement channels

The input switch allows a different combination of the number of voltage / resistance measurement channels. In this case, one current measurement channel uses connector pins that correspond to two voltage measurement channels (i.e., for example, 8 voltage measurement channels and 4 resistance channels can be turned on).


The module allows to implement a redundant connection scheme to the signal sources both at the voltage measurement mode and at the resistance measurement mode.

Galvanic isolation

See the main features of LTR modules

External signals connector

Hardware description, assignment and connection of signals is given in User's Guide.


  • ltr114api.pdf (filesize: 950 649 bytes, date: 29.07.2010)

    LTR114 module. Programmer's Guide.

  • ltrapi_en.pdf (filesize: 604 618 bytes, date: 15.02.2018)

    Ltrapi basic library. Programmer's Guide.

  • ltr_cross_sdk_en.pdf (filesize: 551 553 bytes, date: 13.02.2018)

    Description of the software for Windows, Linux, FreeBSD and QNX.

  • ltr_en.pdf (filesize: 11 066 427 bytes, date: 25.12.2017)

    LTR modular DAQ system. User's Guide (revision 3.1.0).

    • General characteristics and principles of construction
    • Working with LTR crate
    • Overview of LTR crate architecture
    • LTR11 ADC module
    • LTR212 (M) strain measurements modules
    • LTR27 measuring module
    • LTR41, LTR42, LTR43 digital I/O and synchronization modules
    • LTR51 frequency meter module
    • LTR22 ADC module
    • LTR24 (-1, -2) ADC modules
    • LTR25 ADC module
    • LTR34 DAC module
    • LTR35 DAC module
    • LTR114 ADC module
    • LTR210 ADC module
    • LTR00 Dummy module
    • Low-level programming of LTR-EU crate
    • Specification
  • ltr_soft_getting_started_en.pdf (filesize: 269 974 bytes, date: 13.02.2018)

    Starting to work with DAQ system LTR. Questions about the software.

LGraph2 software package

  • (filesize: 26 786 707 bytes, date: 11.10.2021)

    LGraph2 is a free multi-channel data recorder for Windows. Version 2.35.20 provides the possibility of simultaneous data visualization and recording from the ADCs: L-502, L-780M, L-783, L-791, E-502, E14-140, E14-140M, E14-440, E-154, E20-10, LTR11, LTR114, LTR27, LTR212, LTR216, LTR22, LTR24, LTR25, LTR51. It requires an updated version of the LComp driver (from version 01.04.2010) and ltrserver (no lower than

Software for Windows

  • lcard-opc-setup.exe (filesize: 12 440 520 bytes, date: 09.04.2019)

    OPC DA Server for L Card data acquisition modules and LTR crate system. Version 1.0.10.

  • lcomp.exe (filesize: 6 342 216 bytes, date: 12.05.2021)

    Beta version. LCOMP library for Windows XP/Vista/Win7/Win8/Win10 32 and 64-bit versions with drivers. The installer and drivers are digitally signed. The library is built on the basis of modern WDM-drivers rewritten on WDF. It includes the WDM driver itself for L-CARD hardware, the DLL library with source code, programming examples, electronic description, etc. The LCOMP library provides support for almost the entire range of products: PCI boards, USB modules. ISA support is excluded.

    The library includes “L-Graph I” software. L-Graph I supports the following devices: L-1450, L-761, L-780, L-783, L-791, E14-140, E-154 and E14-440. Files recorded by L-Graph I can also be read and processed using the demo-version of PowerGraph v.3.X.

  • ltrd-setup.exe (filesize: 1 467 408 bytes, date: 19.08.2021)

    The ltrd service. Version Provides communication with LTR crates. It is a replacement for the LTRserver software while maintaining the compatibility of the program interface. ltrd is designed for the same purpose as LTRserver, but it is a service that runs when the system is started. The graphical interface to the service is provided by a separate LTR Manager program.

    Attention! Only one of the programs ltrd or LTRserver can work at a time.

  • ltrdll.exe (filesize: 1 328 600 bytes, date: 30.11.2021)

    Libraries for working with LTR crates and modules. Version 1.32.30.

  • ltrmanager_setup.exe (filesize: 9 751 808 bytes, date: 04.05.2021)

    LTR Manager software. Version 1.5.2. Graphical interface to the ltrd service. Provides an interface similar to the LTRserver interface when working through the ltrd service.


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