LTR43 Module for input and output of digital signals

Module for input and output of digital signals
  • Digital asynchronous input/output for standard TTL lines
  • Synchronization of data acquisition in crate and in multi-crate system
  • RS-485 interface for external user functions
  • Power outputs at the external connector

Discrete I/O – 32 discrete parallel channels, organized as four 8-bit ports with software configuration to input or output of each port. When reading, physically present logical levels on the inputs/outputs of 32 channels are always read, regardless of the port settings for input or output.

At the input LTR43 has asynchronous and quasi-synchronous mode, at the output - only asynchronous one.

Connection of "dry contact" signal sources is possible. In the basic modification, the LTR43 has "resistor braces" of the input lines to a high logic level. Also a special modification of LTR43-0 with braces to a low logic level is available for order.

Built-in functions: data acquisition synchronization, RS-485 interface for non-operative control of external devices, including control of several LE-41 amplifiers; there are stabilized power outputs at the external connector.

The main technical characteristics
Number of asynchronous input/output signals 32 (parallel, asynchronous, with output resolution and with direction setting - separately for each byte)
Number of bi-directional synchronization signals 2
Уровни сигналов ввода/вывода и синхронизации TTL, 5 V - logic
Maximum output current of input/output and synchronization lines, configured to output ±10 mA
Input current of logic "0" of input/output signals About 1 mA
Input current of logic "1" of input/output signals Not more than 0,3 mA
Input current of the logic synchronization signal Not more than 10 μA
"Resistor pull" of the input digital lines:
LTR43 (basic modification)
LTR43-0 (special modification, note 1
4.7 kOhm relative to + 5V LTR43
2.2 kOhm relative to GND LTR43-0
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
Additional functions defined by the alternative configuration of certain inputs/outputs
Number of RS-485 ports 1
Power supply outputs of external devices · Output voltage ± 12 V (stabilized)
· Maximum output current of load 120 mA
· Maximum capacitive load 1000 μF
Galvanic isolation of the additional signals section (A485, B485, AGND, + 12V, -12V) relative to any of I/O signals of the same module 150 V
Galvanic isolation
See the main features of LTR modules


1. LTR43 and LTR43-0 modules are software indistinguishable and outwardly differ only by the label. 2. The LTR43 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

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