VARIO RTD 2 - pma
Contents
1. 12 d YUH 128 E 57558004 57558011 Figure 5 Sensor connections Figure 6 Sensor connections in 2 and 3 wire technology with in 4 wire technology with shield shield connection connection A Channel 1 2 wire technology A Channel 1 4 wire technology B Channel 2 3 wire technology B Channel 2 2 wire technology 9499 040 68911 7 VARIO RTD 2 Programming Data ID code TFhex 127 dec Length code O2hex Input address area 4 bytes Output address area 4 bytes Parameter channel PCP 10 bytes Register length bus 4 bytes Process Data Words Output Data Words for the Configuration of the Terminal see page 11 Word bit view Byte bit view Channel 1 Assignment Configu Connection Ro Resol Format Sensor type ration type ution Word bit view Byte bit view Channel 2 Assignment ET Connection Ro Resol Format Sensor type ration type ution 8 9499 040 68911 VARIO RTD 2 Assignment of the Terminal Points to the Input Data Word see page 14 Word bit view Byte bit view Word Bit Byte Bit 15 19 13 12 1110 o 8 7 6ls 3 2 1 0 6 1514 3 2 1 7 6 5 4 312 110 Byte bit view Terminal points chamnel 2 Terminal Signal Terminal point 1 1 sensor 1 pl Signa2. 05 Temperature values can be converted from C to F with this TrsT o 2 32 Where T F Temperature in F T C Temperature in C 22 9499 040 68911 VARIO RTD 2 Input Measuring Ranges 2nnen 3980 8502 Ro 10 o 3000 uN 106277 2nnen 3980 48502 Ro 10 d godi g ee S SAMA ANO _7R 180 C 4356 2 5 AcC to DIN 60 C 76 F 180 C 356 F ANC 180 C 4356 Temperature 1 Ro 10 22 3000 Q 0 777 bi d 4 sensors Cu10 70 C 94 F 500 C 932 F 5 Cu50 50 C 58 F 200 C 392 F 6 Cu53 50 C 58 F 180 C 356 F 7 Ni 1000 L amp G 50 C 58 F 160 C 320 F 8 Ni 500 Viessmann 60 C 76 F 250 C 482 F 9 KTY81 110 55 C 67 F 150 C 302 F 10 KTY84 40 C 40 F 300 C 572 F 11 Reserved 12 13 Relative 0 4 KQ Ro x 100 potentiometer 400 maximum range 14 00 400 Linear resistan 15 nde 00 4000 Q H The number No corresponds to the code of the sensor type in bit 3 through bit O of the process data output vvord 9499 040 68911 23 VARIO RTD 2 Measuring Errors Systematic Measuring Errors During Temperature Measurement With Resistance Thermometers When measuring temperatures with resistance 4 Wire Technology thermometers systematic measuring errors are
3. inputs and internal bus This means that the user must provide signals with safe isolation During configuration ensure that no isolating voltage is specified between the analog for the thermistor detection if required Installation Instructions High current flowing through the potential jumpers Uy and Us raises the temperature of the potential jumpers and the temperature inside the terminal Observe the following instructions to keep the current flowing through the voltage jumpers of the analog terminals as low as possible If this is not possible in your application and if you are using analog terminals in a main circuit together with other terminals place the analog terminals behind all the other terminals at the end of the main circuit Each of the analog terminals needs a separate main circuit 4 9499 040 68911 VARIO RTD 2 Internal Circuit Diagram INTERBUS H ZN NN i E dr EEPROM NE dB 2 m m e E 24 V Ug 24 V Uy al A F 57551003 e e ib lb ea Figure 3 Internal wiring of the terminal points INTERBUS protocol chip Optocoupler DC DC converter with electrical isolation Microprocessor with multiplexer and analog digital converter Reference voltage Electrically erasable programmable read only memory Amplifier 9499 040
4. 0 08 320 mQ 00to4kQ F0 13 x 15Q x 10 13 5 10 10 40 a Average sensitivity for the calculation of tolerance values x Additional error due to connection using 2 wire technology see Systematic Errors During Temperature Measurement In 2 Wire Technology on page 26 Temperature response at 25 C to 55 C 13 F to 131 F 2 3 4 wire 12 ppm C 45 ppm C technology 9499 040 68911 29 VARIO RTD 2 Technical Data Housing dimensions width x height x depth 12 2 mm x 120 mm x 66 6 mm 0 480 in x 4 724 in x 2 622 in Weight 46 g without connector Operating mode Process data operation with 2 words Connection type of the sensors 2 3 and 4 wire technology Permissible temperature operation 25 C to 55 C 13 F to 131 F Permissible temperature storage transport 25 C to 85 C 13 F to 185 F Permissible humidity operation 75 on average 85 occasionally no condensation In the range from 25 C to 55 C 13 increased humidity gt 85 must be ta H F to 131 F appropriate measures against ken Permissible humidity storage transport 75 on average 85 occasionally For a short period slight condensation H terminal is brought into a closed room from a vehicle no condensation may appear on the housing if for example the Permissible air pressure operation 80 kPa to 106 kPa
5. 20 17 0 43 0 14 0 36 K Viessmann KTY 81 110 10 7 Q K 0 07 x 0 11K x 0 07 0 11 K 0 06 0 09 K KTY 84 6 2 0 K 0 06 x x0 19K x 20 06 0 19K 0 05 0 16 K Linear resistance 0 Q to 400 Q 0 025 x 100 MQ x 0 025 100 MQ 0 019 75 mQ 00to4kQ 10 03 x 41 2Q xX 0 03 1 20 140 026 1Q a Average sensitivity for the calculation of tolerance values x Additional error due to connection using 2 wire technology see Systematic Errors During Temperature Measurement In 2 Wire Technology on page 26 28 9499 040 68911 VARIO RTD 2 Maximum Measuring Tolerances at 25 C 77 F Temperature sensors PT 100 0 385 0 12 x 1 04K x 40 12 1 04K 0 10 0 83K PT 1000 3 85 Q K 40 15 x 11 3K x 0 15 1 3K 10 12 1 04K Ni 100 0 617 0 36 x 0 65K x 40 36 0 65K 0 29 0 52K Ni 1000 6 17 Q K 40 45 x 0 81K x 40 45 0 81K 0 36 0 65K Cu 50 0 213 0 47 x 40 94 K x 40 47 0 94 0 38 0 75 Ni 1000 L amp G 15 6 Q K x0 56 x 20 89 x 0 5696 0 89 K 0 44 0 71 Ni 500 2 8Q K 20 72 1 79K x 0 72 1 79 10 57 1 43K Viessmann KTY 81 110 10 7 Q K 0 31 x 0 47K x 40 31 0 47 K 40 25 0 37 KTY 84 6 2Q K 0 27 x 0 81K x 40 27 0 81 K 0 22 0 65K Linear resistance 0 to 400 0 10 x 400 MQ x 0 10 400 mQ
6. often the cause of incorrect measured results The sowie technology is the most precise way of measuring see Figure 12 There are three main ways to connect the sensors 2 3 and 4 wire technology 5755B012 Figure 12 Connection of resistance thermometers in 4 wire technology In 4 wire technology a constant current is sent through the sensor via the I and l cables Two further cables U and U can be used to tap and measure the temperature related voltage at the sensor The cable resistances have absolutely no effect on the measurement 24 9499 040 68911 VARIO RTD 2 3 Wire Technology N On 451 Q S Q 5755B018 Connection of resistance thermometers in 3 wire technology Figure 13 In 3 wire technology the effect of the cable resistance on the measured result in the terminal is eliminated or minimized by multiple measuring of the temperature related voltage and corresponding calculations The results are almost as good in terms of quality as with 4 wire technology in Figure 12 However 4 wire technology offers better results in environments prone to interference 2 Wire Technology N 351
7. 040 68911 15 VARIO RTD 2 Formats for Representing Measured Values Format 1 IB Standard Default Setting The measured value is represented in bits 14 through 0 An additional bit bit 15 is available as a sign bit This format supports extended diagnostics Values gt 8000 indicate an error The error codes are listed on page 15 7 55641008 Bild 9 Measured value representation in format 1 IB standard 15 bits SB Sign bit AV Analog value Typical Analog Values Depending on the Resolution 8002 Open circuit 8001 Over range 400 4000 see page 23 2710 10000 1000 0 OFAO 4000 400 0 4000 400 4000 40 x Ro 00A0 10 1 0 10 1 0 10 0 10 x Ro 0001 1 0 1 1 0 1 1 0 01 x Ro 0000 0 0 0 0 0 FFFF 1 0 1 m 16 9499 040 68911 VARIO RTD 2 FC18 1000 100 0 8080 Under range see table on page 23 8002 Short circuit 8002 Open circuit 8001 gt 325 12 325 12 3251 2 Over range see page 23 2710 10000 100 00 1000 0 100 00 1000 0 10 x Ro 03E8 4000 10 00 100 0 10 00 100 0 1 x Ro 0001 1 0 01 0 1 0 01 0 1 0 01 x Rg 0000 0 0 0 0 0 FFFF 1 0 01 D8FO 10000 100 00 8080 Under range see page 23 8002 Short circuit 3 If the measured value is outside the representation area o
8. 68911 VARIO RTD 2 Electrical Isolation INTERBUS INTERBUS Local bus IN Bus interface Local bus OUT 7 5 V DC MB WB U 7 5 V DC I 4 Wl U 24 V DC 24 V DC MM A VO interface B and 5 microprocessor Electrical isolation between area AandB Ground potential Analog inputs 5722A007 Bild 4 Electrical isolation of the single function areas Connection Connection of the Thermocouples 3 Always connect temperature shunts using shielded twisted pair cables Connection of the Shield 152 The connection of the shield is shown in the examples Figure 5 Connect the shielding of the Inline terminal using the shield connector clamp The clamp connects the shield directly to FE on the terminal side Additional wiring is not necessary Isolate the shield at the sensor Sensor Connection In 4 Wire Technology 152 A sensor can only be connected to channel 1 in 4 wire technology In this case the sensor on channel 2 can only be connected in 2 wire technology 6 9499 040 68911 VARIO RTD 2 Connection Examples IS When connecting the shield at the terminal you must insulate the shield on the sensor side shown in gray in Figure 5 and Figure 6 Use a connector with shield connection when installing the sensors Figure 5 shows the connection schematically without shield connector Connection of Passive Sensors
9. up to 2000 m 6561 680 ft above sea level Permissible air pressure storage transport 70 kPa to 106 kPa up to 3000 m 9842 520 ft above sea level Degree of protection IP 20 according to IEC 60529 Class of protection Class 3 according to VDE 0106 IEC 60536 local bus interface Data routing Communications voltage UL 7 5V Current consumption from UL 43 mA typical I O supply voltage Uana 24 V DC Current consumption from UANA 11 mA typical Total power consumption 590 mW typical 9499 040 68911 VARIO RTD 2 Connection method Voltage routing Number Two inputs for resistive temperature sensors Connection of the signals 2 3 or 4 wire shielded sensor cable Sensor types that can be used Pt Ni Cu KTY Standards for characteristic curves According to DIN according to SAMA Conversion time of the A D converter 120 us typical Process data update Dependent on the connection method Both channels in 2 wire technology 20 ms One channel in 2 wire technology 20 ms one channel in 4 wire technology Both channels in 3 wire technology 32 ms None bus terminal supply Upgy and the I O supply Uy Us from separate power supply units For the electrical isolation between logic level and I O area it is necessary to provide the Interconnection of the 24 V power supplies is not allowed Com
10. 57550013 Connection of resistance thermometers in 2 vvire technology Figure 14 2 wire technology is a cost effective connection method The U and U cables are no longer needed here The temperature related voltage is not directly measured at the sensor and therefore not falsified by the two cable resistances R see Figure 14 The measuring errors that occur can make the entire measurement unusable see diagrams in Figure 15 to Figure 17 Hovvever these diagrams also shovv the positions in the measuring system vvhere steps can be taken to minimize these errors 9499 040 68911 25 VARIO RTD 2 Systematic Errors During Temperature Measurement In 2 Wire Technology 15 0 A k 1 12 0 AT 9 0 6 0 3 0 3 0 0 00 25 5 0 7 5 100 125 15 0 17 5m 20 0 I 57551014 Figure 15 Systematic temperature measuring error AT depending on the cable length 1 Curves depending on the cable diameter A 1 Temperature measuring error for A 0 14 mm 26 AWG 2 Temperature measuring error for A 0 25 mm 24 AWG 3 Temperature measuring error for A 0 50 mm 20 AWG Measuring error valid for copper cable y 57 m Qmm Ty 25 C 77 F and PT 100 sensor 0 01 02 03 04 05 06 07 08 0 9 m1 0 I 57550015 Figure 16 Systematic temperature measuring error AT depending on the cable diameter A Measuring error
11. VARIO RTD 2 I O Extension Module With Two Analog Input Channels for the Connection of Temperature Shunts RTD User Manual 02 2003 57551001 This data sheet is only valid in association with the documents of the used fieldbus coupler H Function The VARIO RTD 2 terminal is designed for use vvithin an VARIO station This terminal provides a two channel input module for resistive temperature sensors This terminal supports platinum or nickel sensors according to the DIN standard and SAMA Directive n addition CU10 CU50 CU53 KTY81 and KTY84 sensors are supported The measuring temperature is represented by a 16 bit value in tvvo data vvords one vvord per channel Features Two inputs for resistive temperature sensors Configuration of the channels via fieldbuss Measured values can be represented in 3 different formats Connection of sensors in 2 3 and 4 wire technology 57550010 Terminal VARIO RTD 2 with connector fitted Figure 1 H All modules will be delivered including connectors and labeling fields 9499 040 68911 VARIO RTD 2 Table of Contents A 1 Safety Note da 4 Installation Iristr ctions 5 n ii ata Rb ERES 4 Internal Circuit DIagralm ct Ge c EA aia 5 Electrical Isolation m 6 COMECON A ee et ota 6 Connection Examples iodo ds di a dt a AIR tania 7 Programming Data iom itn et UI EDEN IE 8 Process Data W
12. e process data input words to the controller board or the computer The three formats for representing the input data are shown in Bild 8 For more detailed information on formats please refer to Formats for Representing Measured Values on page 16 Process data word 0 Process data word 1 Channel 1 Channel 2 MSB LSB S TSISTSTSISSTTSTS STET T Format 3 re ielelein ei l l T lsfal la 110 noma 5755A009 Bild 8 Sequence of the process data input words and representation of the bits of the first process data word in different formats MSB Most significant bit LSB Least significant bit SB Sign bit AV Analog value Reserved OC Open circuit short circuit OR Over range 14 9499 040 68911 VARIO RTD 2 The IB standard process data format 1 supports extended diagnostics The following error codes are possible 8001 Over range 8002 Open circuit or short circuit only available in the temperature range 8004 Measured value invalid no valid measured value available 8010 Configuration invalid 8040 Terminal faulty 8080 Under range Open Circuit Short Circuit Detection Open circuit is detected according to the following table Yes Open circuit short circuit is detected The cable is not connected in this connection method No Open circuit short circuit is not detected because the value is a valid measured value 9499
13. f the process data the error message Over range or Under range is displayed 9499 040 6891 1 VARIO RTD 2 Format 2 This format can be selected for each channel using bits 5 and 4 bit combination 01 yn of the corresponding process data output word The measured value is represented in bits 14 through 3 The remaining 4 bits are available as sign and error bits 5 SE a 10 5 17 ES ES 55200060 Bild 10 Measured value representation in format 2 12 bits SB Sign bit AV Analog value 0 Reserved OC Open circuit short circuit OR Over range 18 9499 040 68911 VARIO RTD 2 Typical Analog Values Depending on the Resolution XXXX XXXX XXXX XXX pin Over range AV positive final value from the table on page 23 2710 10000 1000 0 100 00 03E8 1000 100 0 10 00 0008 8 0 8 0 08 0000 0 0 0 FFF8 8 0 8 0 08 FC18 1000 100 0 10 00 XXXX XXXX XXXX XXX pin Under range AV negative final value from the table on page 23 XXXX XXXX XXXX XX Xpin Open circuit short circuit AV 7 negative final value from the table on page 23 AM Analog value x Can have the values 0 or 1 3 If the measured value is outside the representation area of the process data bit O is set to 1 On an open circuit short circuit bit 1 is set to 1 9499 040 68911 19 VARIO RTD 2 Format 3 This format can be selected for each channel using bits 5 a
14. he message Measured value invalid error code 8004hex appears in the process input words After 1 s maximum the preset configuration is accepted and the first measured value is available Default Connection 3 wire technology Ro 100 Q Resolution 0 1 C Format Format 1 IB standard Sensor type PT 100 DIN If you change the configuration the corresponding channel is re initialized The message Measured value invalid error code ES004 ex appears in the process data output words for 100 ms maximum If the configuration is invalid the message Configuration invalid appears error code 801 One Please note that extended diagnostics is only possible if IB standard is configured as the format for representing the measured values Since this format is preset on the terminal it can be used straight away after power up 10 9499 040 68911 VARIO RTD 2 One process data output word is available for the configuration of each channel Process data word 0 Process data word 1 Channel 1 Channel 2 MSB LSB l l Configuration Connection RO Resolution Format Sensor type type 5755A006 Bild 7 Process data output words 9499 040 68911 11 VARIO RTD 2 Bit 15 and bit 14 You must set bit 15 of the corresponding output word to 1 to configure the terminal or a certain channel If bit 15 0 the preset configuration is active Bit 14 is of no importance at present therefore
15. influenced but it is mentioned here for the sake of completeness The equation for the calculation of the cable resistance is Roy X 1 0 0043 x Ty R x 1 0 0043 2 x T XXA K VVhere RL Cable resistance in Q 20 Cable resistance at 20 C 68 F in O Cable length in m X Specific electrical resistance of copper in Qmm m A Cable diameter in mm 0 0043 1 K Temperature coefficient for copper Tu Ambient temperature cable temperature in C Since there are two cable resistances in the measuring system forward and return the value must be doubled The absolute measuring error in Kelvin K is provided for platinum sensors according to DIN using the average temperature coefficient o a 0 385 Q K for PT100 a 3 85 O K for PT1000 9499 040 68911 27 VARIO RTD 2 Tolerance and Temperature Response Typical Measuring Tolerances at 25 C 77 F Temperature sensors PT 100 0 385 0 03 x 0 26K x 40 03 0 26K 0 02 0 2 K PT 1000 3 85 Q K 0 04 x 20 31 K x 20 04 0 31 0 03 0 26 K Ni 100 0 617 0 09 x 20 16 K x 1 0 09 0 16 K 20 07 0 12 K Ni 1000 6 17 0 11 x 0 2K x 0 11 0 2 K 0 09 0 16 K Cu 50 0 213 0 24 x 20 47 K x 40 24 0 47 K 40 18 0 35 K Ni 1000 L amp G 5 6 Q K 0 13 x x021K x 0 13 0 21K 20 11 0 18 K Ni 500 2 8 10 17 x 40 43K x
16. it should be set to O Bit 13 and bit 12 00 13 vvire 01 2 wire 10 4 wire only channel 1 w N o 11 Reserved Bit 11 through bit 8 0 10000 100 8 110001240 1 10001110 9 11001 1300 2 0010120 10 1010 1400 3 10011 130 11 11011 1500 4 10100150 12 11100 1000 5 101011120 13 1110111500 6 101101150 14 11110 12000 7 1011111200 15 1111113000 adiustable Bit 7 and bit 6 0 00 10 1 C 1 0 10 10 1 01 0 01 C 0 1 0 01 0 1 2 10 0 12 Reserved Reserved Reserved 3 11 10 01 F 12 9499 040 68911 VARIO RTD 2 Bit 5 and bit 4 Format 1 IB standard 15 bits sign bit with extended diagnostics Compatible with ST format Format 2 12 bits sign bit 3 diagnostic bits Format 3 15 bits sign bit 3 11 Reserved Bit 3 through bit 0 0 10000 Pt DIN 8 1000 Ni 500 Viessmann 1 10001 Pt SAMA 9 1001 KTY 81 110 2 100101Ni DIN 10 11010 KTY 84 3 0011 Ni SAMA 11 11011 Reserved 4 101001Cu10 12 11100 Reserved 5 10101 Cu50 13 11101 Potentiometer 96 6 101101Cu53 14 11110 Linear R O through 400 Q 7 101111Ni 1000 Landis amp Gyr 15 1111 Linear R O through 4000 2 9499 040 6891 1 13 VARIO RTD 2 Process Data Input Words The measured values are transmitted per channel through th
17. l reference Terminal point 1 2 l4 sensor 1 Terminal point 1 3 U4 sensor 1 channe Shield FE Terminal point 1 4 Word bit Word Bit 15114 13 t2 11 10 9 8 7 6 5 4 3 2 1 0 Byte Bit Signal Terminal point 2 1 154 sensor 2 6 1514 3 2 1 7 6 5 4 312 110 Signal reference Terminal point 2 2 l2 sensor 2 Terminal point 2 3 U sensor 2 Shielding Terminal point 2 4 9499 040 68911 VARIO RTD 2 Process Data Output Words You can configure the channels of the terminal with the two process data output words The following configurations are possible for every channel independent of the other channel Sensor connection method Value of the Ro reference resistance Setting the resolution Selection of the format for representing the measured values Setting the sensor type The two channels are dependent on each other for the connection method If the 4 wire mode is activated for channel 1 channel 2 can only be operated using the 2 wire connection method The 4 wire connection method is only available for channel 1 Configuration errors are indicated by the corresponding error code as long as the IB standard format is configured as the format for representing the measured values The configuration setting is saved in a volatile memory It must be transmitted in each INTERBUS cycle After the Inline station has been powered up t
18. mon Potentials 24 V main supply Uy 24 V segment voltage Us and GND have the same potential FE functional earth ground is a separate potential area Isolated Voltages in the VARIO RTD 2 Terminal Test Distance Test Voltage 7 5 V supply bus logic 24 V analog supply analog I O 500 V AC 50 Hz 1 min 7 5 V supply bus logic functional earth ground 500 V AC 50 Hz 1 min 24 V analog supply analog 1 0 functional earth ground 500 V AC 50 Hz 1 min 9499 040 6891 1 31 VARIO RTD 2 Failure of the internal voltage supply Yes Failure or dropping of communications voltage Yes I O error message to the bus terminal UL I O error user error Yes see page 15 Ordering Data Terminal with two resistive temperature sensor VARIO RTD 2 KSVC 103 00321 inputs with connectors and labeling fields PMA Prozess und Maschinen Automation GmbH Miramstrasse 87 34123 Kassel Germany 49 0 561 505 1307 44 49 0 561 505 1710 a pma online E www pma online de 32 9499 040 6891 1 Subject to technical modification
19. nd 4 bit combination 10 of the corresponding process data output word The measured value is represented in bits 14 to 0 An additional bit bit 15 is available as a sign bit 7 777F 725117757777 55641008 Bild 11 Measured value representation in format 3 15 bits SB Sign bit AV Analog value 20 9499 040 68911 VARIO RTD 2 Typical Analog Values Depending on the Resolution 7FFF 32767 gt 2048 Upper limit value 1 LSB Over range 7D00 32000 2000 2710 10000 1000 0 625 000A 10 1 0 625 0001 0 1 0 0625 0000 0 0 0 FFFF 1 0 1 FC18 1000 100 0 Lovver limit value 1 LSB Under range Lovver limit value 2 LSB Open circuit short circuit TFFF 32767 gt 4096 Upper limit value 1 LSB Over range 7D00 32000 320 00 4000 2710 10000 100 0 1250 0001 1 0 1 0 125 0000 0 0 0 FFFF 1 1 0 D8FO 10000 100 0 Lower limit value 1 LSB Under range Lower limit value 2 LSB Open circuit short circuit The limit values can be found on page 23 9499 040 68911 VARIO RTD 2 Measuring Ranges Measuring Ranges Depending on the Resolution IB Standard Format 00 273 C to 3276 8 C Resolution 0 1 C 01 273 C to 327 68 C Resolution 0 01 C 10 459 F to 3276 8 F Resolution 0 1 F 11 459 F to 327 68 F Resolution 0 01 F
20. ords eias di ana Lote dia ce dd dd ree da e he diee d dd 8 Formats for Representing Measured Values ssssseene ener nnns 16 Measuring Ranges nene a UH be t ege OU UE E pa 22 Measuririg EITOIS o E ei E MUR 24 Tolerance and Temperature Response sss em ener ennt 28 Technical Bata suiit ie poat nemi 30 Ordering Data idein tete e deae eh e ente n ta Ee ER eee ego e 32 2 9499 040 68911 VARIO RTD 2 Figure 2 57550002 VARIO RTD 2 with the appropriate connector Local Diagnostic and Status Indicators D Green Bus diagnostics Pin Assignment for 2 and 3 Wire Termination 1 1 14 RTD sensor 1 1 2 h Constant current supply 1 3 U4 Measuring input sensor 1 2 1 lot RTD sensor 2 2 2 l2 Constant current supply 2 3 U2 Measuring input sensor 2 1 4 2 4 Shield Shield connection channel 1 and 2 Pin Assignment for 4 Wire Termination on Channel 1 and 2 Wire Termination on Channel 2 1 1 14 RTD sensor 1 1 2 h Constant current supply 1 3 U4 Measuring input sensor 1 2 3 Ul Measuring input sensor 1 2 1 lot RTD sensor 2 2 2 12 Constant current supply 1 4 2 4 Shield Shield connection channel 1 and 2 3 A sensor can only be connected to channel 1 using 4 wire technology 9499 040 68911 VARIO RTD 2 Safety Note
21. valid for copper cable y 57 m Qmm Ty 25 C 77 F 5m 16 404 ft and PT 100 sensor 25 K aa 1 5 1 0 0 5 0 0 30 20 10 10 20 30 40 50 C 60 T 57550016 Figure 17 Systematic temperature measuring error AT depending on the Ty cable temperature Measuring error valid for copper cable y 57 m Omm 5 m 16 404 ft A 0 25 mm 24 AWG and PT 100 sensor 26 9499 040 68911 VARIO RTD 2 All diagrams show that the increase in cable resistance causes the measuring error A considerable improvement is made through the use of PT 1000 sensors Due to the 10 fold higher temperature coefficient o a 0 385 Q K for PT100 to a 3 85 Q K for PT1000 the effect of the cable resistance on the measurement is decreased by factor 10 All errors in the diagrams above would be reduced by factor 10 Diagram 1 clearly shows the influence of the cable length on the cable resistance and therefore on the measuring error The solution is to use the shortest possible sensor cables Diagram 2 shows the influence of the cable diameter on the cable resistance It can be seen that cables with a diameter of less than 0 5 mm 20 AWG cause errors to increase exponentially Diagram 3 shows the influence of the ambient temperature on the cable resistance This parameter does not play a great role and can hardly be
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