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Description and application


This temperature sensor with a digital output RS 485 (MODBUS) - KSD 112 is designed to outdoor environment.  In the application segment of Railway Vehicles, it is used for example to measure temperature of the air in locomotive engine rooms, it can be a part of the temperature control system in passenger compartments or is used to indicate temperature in the engine room as a part of the fire protection system.

The temperature sensor with a digital output RS 485 (MODBUS) - KSD 112 for outdoor environment consist of a plastic head and a metal case, where the sensing element for temperature measurement (sensor) is placed. In the head, there is a terminal block with a converter located, to which a supply cable for sensor supply and digital output signal according to the sensor type is connected through a cable grommet or a connector.

KSD 112A, KSD 112AK – MODBUS/RTU communication protocol, communication via the RS485 bus

The temperature range of sensor use is defined in the table of technical parameters for the individual versions of sensors. The sensors meet the ingress protection of IP 65 according to EN 60529, as amended. Recommended installation of the sensor:

  • for measurement of outdoor air temperature – the installation is recommended on the coolestside of the building (the northern or the northwest one) in a way that the sensor is not 097.11en exposed to a direct sun light. The installation is recommended in 2/3 of the height of the building wall.
  • for measurement of indoor air temperature in rooms, offices or in production halls – the installation is recommended on an inner wall at the height of 1.5 m, in areas of movement of persons, at places not exposed to sunlight and not influenced by heat from heating radiators or lighting

The sensor is designed to be operated in a chemically non-aggressive environment, the use must be chosen with regard to the temperature and chemical resistance of the sensor head.


  • CONEC 43-00092 connection plug
  • connection cables with a straight RKT connector or right-angled RKWT connector


  • The type tests are carried out by a notified body according to EN 50155 standard, as amended, Railway applications – Electronic equipment used on rolling stock, Art. 12.2.9, 12.2.11

- Electromagnetic Compatibility in accordance with EN 50121-3-2, as amended

- Insulation test in accordance with EN 50155, as amended

- Shock and vibration tests in accordance with EN 61373, as amended

The product meets parameters in accordance with EN 45545-2, as amended, Fire protection on railway vehicles - Part 2: Requirements for fire behavior of materials and components. Can be supplied with materials complying with fire safety standard NFPA 130, as amended.

  • Manufacturer provides EU Declaration of Conformity.
  • Calibration – The final metrological inspection – comparison with standards or working instruments – is carried out for all the products. Continuity of the standards and working measuring instruments is ensured within the meaning of the Section 5 of Act no.505/1990 on metrology. The manufacturer offers a possibility to supply the sensors calibrated in SENSIT s.r.o.’s laboratory (according to requirements of the EN ISO/IEC 17025 standard, as amended) or in an Accredited laboratory.  

  • Specifications
Sensor type
(K - with connector)
KSD 112A
Output signal RS 485 / MODBUS RTU
Measuring range -30 to 70 °C
Accuracy of the electronics *) ± 0.2 °C
Type / Accuracy of the sensing element Pt 1000 / ± (0.3 °C + 0.0005|t|)
Supply voltage (U) 15 to 30 V DC
Rated supply voltage (Un) 24 V DC
Consumption / Supply current maximum: 500 mW
typical: 300 mW
Ingress protection IP 65 in accordance with EN 60529, as amended
Length of the stem 50 mm
Standard stem diameter 6 ± 0.2 mm
Material of the stem stainless steel DIN 1.4301
Insulation resistance > 200 MΩ at 500 V/DC, 25°C ± 3 °C; humidity < 85 %
Dimensions of the head 70 × 63 × 34 mm
Material of the head LEXAN (meets standard EN 45545-2)
Connector type in the head
(for sensors with a connector)
RSFM4 - M12- Lumberg
Recommended wire cross-section
(for sensors with a grommet)
0.14 to 1 mm2
Working conditions ambient temperature: -40 to 80 °C
relative air humidity: max. 100 %
atmospheric pressure: 70 to 107 kPa
Weight min. 150 g

*) Measurement error of KSD 112A temperature sensor depends on the flow rate and supply voltage (method error) and can be within -1.0 to 1.5 °C.


Shock and vibration tests

category 1, class B in accordance with EN 61373
Elektromagnetic compatibility in accordance with EN 50121-3-2
Insulation test 1.5 kVDC for time 1 minute in accordance with EN 50155
Fire protection resistance
in accordance with EN 45545 (possible acc. to NFPA 130)

Note: Manufacturer reserves the right to make changes in design and technical characteristics of the products. For actual information, please always contact your dealer.

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