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Description and application


KST RS 485 convertors temperature - RS 485 is intended for converting the signal of  Pt 1000/3850 resistance-type temperature sensing elements to the digital signal RS 485 / MODBUS RTU. These converters can be utilised in any control system compatible with RS 485 digital output. Standard measuring ranges of the converter is -50 to 200 °C. Operating temperature range is -40 °C to 80 °C. These limits must not be exceeded even for a short time.

The convertors are designed to be operated in a chemically non-aggressive environment.

KST RS 485 convertor - the plastic case is made of LEXAN material meets requirements of EN 45545-2, and is identical to, for example, the connection head of KS 120 sensors. It is provided with a wall bracket or with a clip for attaching to a DIN rail. The plastic box meets the IP 65 ingress protection requirements according to the EN 60 529 standard.


  • 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 material of the plastic box and PCB meets a set of requirements for the R 24 materials according to the Table 5 for the fire hazard level HL1-HL2-HL3 of the EN 45545-2 standard, as amended. 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
  • Dimensional draft
Type of convertor KST 485
Input signal Pt 1000/3850
Output signal RS 485 / MODBUS RTU
Communication properties communication via RS 485 maximum segment length is 1200 m, asynchronous transfer
preset transfer speed 9600 Bd optional transfer speeds 1200, 2400, 4800, 9600, 19200, 57600, 115200 Bd - DIP switch
247 modules / 1 serial port
protocol ModBus RTU 1 stop bit, without parity
Measuring range -50 to 200 °C
Power supply 10 to 35 V DC (unstabilized) 14 to 24 V AC
Power consumption max. 1000 mW
Nominal supply voltage Un 24 VDC
Accuracy of electronics 0.05 %
Accuracy of sensing element
Resolution 0.01 °C
Material of the boxes LEXAN (fulfield standard EN 45545-2)
Ingress protection
KST: IP 65 in accordance with EN 60 529
Mean working life≈ MTTF* 1.95 x 106 hrs, based on a theoretical calculation

*) Under the environmental and operational conditions specified in appoved testing methodology

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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