LTR41 Input module for digital signals

Input module for digital signals
  • Galvanically isolated connection of discrete signals sources
  • Synchronization of data acquisition in crate and in multi-crate system
  • + 5V power output at the external connector

LTR41 is used in automated discrete monitoring systems in the tasks of managing technological processes, laboratory and production equipment; in industrial automation systems.

The module provides isolated connection of discrete sensors. It is used in systems with increased requirements for reliability and noise immunity.

Extension of the LTR41 range of input of specific signals 0 - 24V and more is possible due to the addition of a resistor into the input circuit.

The main technical characteristics
Number of asynchronous input signals 16
Type of inputs Compatible with the output of TTL/CMOS 5 V logic (with a logical "1" current of more than 3.5 mA), as well as with a current output of up to 15 mA. Parallel inputs, asynchronous or quasi-synchronous modes.
Input current of logic "0" of input signals Not more than 1 mA
Input current of logic "1" of input signals Not less than3,5 mA
Typical input voltage/current at the switching point +2,2 V / 2,1 mA (Note 2)
Maximum allowable input voltage / current ±12 V long-term (Note 1)
Maximum allowable value of the input current of any direction 25 mA (long-term)
Galvanic isolation between output signals Channel-by-channel up to 200 V
Synchronization of data acquisition in a crate and in a multi-crate system
Number of bi-directional synchronization signals 2 (second mark and "START" mark)
Levels of synchronization signals Compatible with TTL, 5V - logic
Maximum output current of synchronization lines configured to output ± 10 mA
Galvanically isolated power output of external devices
Stabilized output voltage +(5 ± 0,1) V
Output load current 300 mA
Maximum capacitive load 1000 μF


1. The maximum value of the input voltage and the switching voltage can be increased by adding an external resistor, the calculation of which is given in the LTR User Manual.

2. LTR41 module can be used for an input switching current of more than 2.1 mA, by adding an external parallel shunt if the voltage drop across the external shunt exceeds 2.5 V. For calculation of the shunt please contact

3. The LTR41 module can not be calibrated.


External signals connector

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

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.


Phone: +7 (495) 785-95-19
Fax: +7 (495) 785-95-14

Sales department:
Technical support:

5 Varshavskoye shosse, corp. 4, build. 2
Moscow 117105
Russian Federation

Send a request

Contact us

About us

More than 3,000 customers worldwide are already using L-CARD electronic equipment for a wide range of research and industrial applications. We are glad to help you at any stage of creating an electronic product: from development and production to post-warranty support.



We are looking for regional distributors providing delivery services and comprehensive after-sales support. If you want to join L-CARD distribution network please contact us.