KD420 User Manual
Contents
1. 3 1 Port 1 KD420 Configuration When used for KD420 configuration Port 1 operates in RS422 mode i e 4 wires plus ground The configuration program KD420CFG EXE runs under Windows There are two common methods for creating an RS422 interface on a Windows computer an RS232 to RS422 converter or a USB RS422 converter The following instructions show the connections KD420 Configuration Connections using a RS232 to RS422 Converter IBM compatible PC with a 9 way serial port Port 1 screw RJ 11 connector terminals view from outside KD420 internal connections O lt RXA 2 3 TXB 9 JE RXB 7 4 gt gl 78282 TXA 8 1 RXA TXB 3 2 J GND 5 5 axe 4 l K2 or K2 TB RS232 to RS422 Converter Pin numbers shown for both K2 and K2 TB GND a a 00 0 000 IMPORTANT The screw terminals and the RJ11 are internally interconnected They are not separate serial ports Use only one at any time Version 1 0 Page 10 KD420 User Guide KD420 Configuration Connections using the KK Systems USB 485 Converter IBM compatible PC with a USB port Port 1 screw RJ 11 connector terminals view from outside Bk D420 internal connections USB 485 Converter 1 O RXA 2 18 l PBN g USB TXA 8 PXA 3 z TXB 3 GND 5 axe IMPORTANT The screw terminals and the RJ11 7 a2. Page 2 Version 1 0 KD420 User Guide 1 1 Quick Start Guide e _ Unpack the unit and check you have the following items KD420 User Manual e The factory configuration of both KD420 serial ports is 9600 baud 8 bits word No parity 1 stop bit If this is not as desired the KD420 can be reconfigured for a wide range of baud rates from 30 to 115200 This requires KD420 s Port 1 to be connected to a Windows computer via an RS422 interface The supplied KD420CFG EXE program is used Port 1 is available on both the 8 way connector and on the RJ11 connector For configuration instructions see page 18 For a Windows computer with RS232 or USB ports a suitable RS422 interface is the KK Systems K2 K2 TB USB 485 KD485 STD If you wish to configure the KD420 via Modbus i e without using the KD420CFG EXE program see page 28 e Refer to the configuration section on page 18 and configure the KD420 as required Version 1 0 Page 3 KD420 User Guide 1 2 Block Diagram Options Switch 12 34 Hod Data Flow Indicator LEDs PORT GND twos t 1 H RJ 11 mh pe TX e 1RX RS485 driver control CG V TXA PORTI 1 i w O gt 6 RS4X gt O J TXB PROCESSOR 010 1V 5 i RXA amp MEMORY 3 O A D CONVERTER aR INPUT 2 sn 4 1 O
3. KD420 User Guide 2 50 3 75 4 100 5 110 6 134 5 7 150 8 300 9 600 10 1200 11 2000 12 2400 13 3600 14 4800 15 7200 16 9600 17 19200 18 38400 19 57600 20 115200 7 1 3 Voltage and current format The following voltage and current 4 20mA format values are used to determine the format used when the KD420 acting as a Modbus Master on its Port 2 writes a voltage or current value to the Modbus Slave device Format Registers Config Value 16 bit integer 1 0 32bit IEEE floating point value big endian 2 1 32bit IEEE floating point value little endian 2 2 ASCII textual float 00 000 format null terminated 8 3 ASCII textual float 0 000E 00 format null terminated 11 4 Version 1 0 Page 30 KD420 User Guide Boolean within 4 20mA range 1 yes 0 no 4 20mA only 1 5 KK Systems Ltd Tates London Road Pyecombe Brighton BN45 7ED Great Britain www kksystems com Version 1 0 Page 31
4. KD420 User Guide 4 Mounting The KD420 clips to a standard 35mm DIN rail Overall Dimensions including terminals E E 29mm 97mm Removing unit from DIN rail Method 1 Lift base of unit upwards Method 2 Use a suitable tool to open up DIN rail clip Version 1 0 N 35mm symmetric DIN rail Page 17 KD420 User Guide 5 Configuration The KD420 is configured by connecting a PC serial port via an RS232 or USB to RS422 converter to the KD420 port 1 and running the supplied KD420CFG EXE configuration program This software provides a graphical interface for configuring the KD420 To connect to the KD420 refer to KD420 Configuration on pages 18 22 Suitable RS232 RS422 or USB RS422 converters are available from KK Systems Ltd 5 1 Installing KD420 Configuration Software To install KD420CFG EXE click on the KD420CFG MSI file and follow the instructions 5 2 Using KD420 Configuration Software In order for KD420CFG EXE to communicate with the KD420 briefly press the button on the KD420 front panel This puts the KD420 into config mode as indicated by the CFG LED being illuminated continuously When in the config mode the KD420 Port 1 communication settings are changed to 9600 n 8 1 and Modbus slave address 1 The KD420 will remain in config mode for 1 minute unless it remains connected to a PC running KD420CFG EXE After this time it will automatically revert to the communication settings and p
5. 20 92 2 SADG SENE ao kk a En Edet a kr 22 5 2 2 1 Noise Reduction sanmsasssnsadnsnudehnssuvnsmssdren 22 5 2 2 2 Performance Options sssseesre sner seerne 23 5 2 3 Modbus Master Settings Musse sure serne rens serr sv vnin sinnis stunt snnnnnn 25 5 2 3 1 Modbus Register Numbering 21 ener errrse renter enter retter 26 5 24 Monitor Page so ore re EEE EE seder idae ine 26 TroUubIeSK ON GT isisisi ea ne ENN 27 7 7 1 6 1 1 KD420 Power Up Problems aassassaias sas sanssanasanssanasanasanasanananaaan 27 6 1 2 KD420CFG EXE unable to connect aiaaiiivavisssssssssssssssssssansnssanaa 27 KD420 Configuration via ModbusS neesesvarenenvenenvvnenvnnenenenennenn 28 Configuration Registers n mmnrsesesvesrervesrersessersessvesersvesvasvenvesvenvesnenvevsenser 28 7 1 1 Modbus Register Numbering 222a vissi isv s ns snari 28 7 4 2 Communications Parameters susvaaavssavssassssssssvsssssanassnaaananan 29 TAS Voltage and current format am ce ar b kupler skr rele kerne 30 KD420 User Guide 1 KD420 Overview The KD420 is an analog sensor to Modbus interface which supports the following analog inputs e analog current 4 20mA a 20V sensor supply is provided e analog voltage 30V to 30V e external relay contact sensing uses the analog voltage input It presents the values in the following ways which are all updated concurrently 1 They are readable
6. LPT Ports to see what COM port number has been allocated by the operating system Version 1 0 Page 27 KD420 User Guide 7 KD420 Configuration via Modbus 7 1 Configuration Registers 7 1 1 Modbus Register Numbering There is often confusion over Modbus register numbering with some manufacturers using the older Modicon 4xxxx notation and others using register numbers based from 1 The Modbus register numbers used with the KD420 should be specified as a decimal number based from zero and with the Modbus function code determining the register type For example to read Modbus holding register 40001 you would specify register 0 and function code 3 read holding registers Similarly to read Modbus input register 30099 you would specify register 98 and function code 4 read input registers The KD420 implements the following Modbus holding registers within the KD420 Port 1 Modbus slave for the purpose of in the field reconfiguration of the KD420 Configuration is performed by updating any of these values in any sequence The configuration update only actually takes effect once the value ABCDh is written to register number 40200 register address 199 The configuration registers starting with register 40201 listed below can be both written to and read from The current effective configuration values can always be read from a similar sequence of registers starting at register 40301 Register Value 40201 200 Port 1 KD420 Slav
7. a Modbus RTU Slave attached to Port 2 KD420 Configuration File Port Firmware Help Modbus Slave Settings Modbus Master Settings ADC Settings Monitor Voltage Current n seconds C Update current value every seconds Starting at register 40003 Starting at register Format Format 16 bit integer 32000 to 32000 Modbus Master Port 2 Configuration i Baud rate 9600 Slave address to write to 1 Bits per word 8 Request timeout 1000 Parity On error rety 3 Stopbits The Modbus master can write voltage and current values in any one of a number of formats Some of these formats will use a number of consecutive 16 bit Modbus holding registers Format Registers 16 bit integer 1 32bit IEEE floating point value big endian 2 32bit IEEE floating point value little endian 2 ASCII textual float 00 000 format null terminated 8 ASCII textual float 0 000E 00 format null terminated 11 Boolean within 4 20mA range 1 yes 0 no current only 1 Version 1 0 Page 25 KD420 User Guide 16 bit integer values measure current as 0 to 64000 in mA x 1000 and voltage as 32000 to 32000 in volts x 1000 5 2 3 1 Modbus Register Numbering There is often confusion over Modbus register numbering with some manufacturers using the older Modicon 4xxxx notation and others using register numbers based from 1 The Modbus register numbers used with the KD420 should be specified as a decimal number bas
8. converter It does not attempt to work it out by looking at which Modbus registers are being read This maximises performance but if e g the Enable voltage channel option is disabled a read of the Voltage registers 40101 onwards will return garbage The Slave Address is the Modbus address on which the KD420 will respond when not in configuration mode Version 1 0 Page 21 KD420 User Guide 5 2 2 ADC Settings The following tab configures A D converter options KD420 Configuration File Port Firmware Help Modbus Slave Settings Modbus Master Settings ADC Settings Monitor Noise reduction ADC noise due to electrical mains frequency interference can be eliminated by averaging the ADC reads over an appropriate period Noise reduction mains frequency v Hertz Performance Options Modbus slave read response times can be decreased by disabling features that are not required C Enable current channel Enable voltage channel C Enable textual ASCII floating point representation 5 2 2 1 Noise Reduction When the 50Hz or 60Hz option is set the KD420 reads the analog value continuously for 20ms or 17ms respectively adds up the readings and divides that by the number of readings taken The number of readings thus averaged is approximately 30 or 26 respectively This provides a high degree of filtering of noise especially mains power line frequency noise Setting this value to non
9. i PORT 2 RXB i eu BV to 33V 3 OR 5 D vo nor cower 0O 6 C mw lt lt 4 RS 485 ISOLATION 5V 2 i RS 485 driver control gt POWER 7 O gt GND SWITCHING POWER SUPPLY INPUT 8 O Port 1 is RS422 485 and is used for the KD420 s Modbus Slave interface It also serves as a configuration port all KD420 features are configured using the supplied KD420CFG EXE Windows program Port 1 is accessible via the 8 way Port 1 terminal block and via the RJ 11 connector Only one of these two connectors may have connections to it at any one time The RJ 11 is provided for specialised applications Port 2 is a composite connection for the two analog voltage and 4 20mA current features and for the 2 wire RS485 interface which can operate as a Modbus Master Pin 4 of Port 2 should always be connected to earth or a good ground This is because Port 2 is fully floating and the grounding helps to eliminate static charge and optimise EMC compatibility Version 1 0 Page 4 KD420 User Guide 1 3 Front Panel Description 4 20mA current within limits Port 2 receiving data Port 1 transmitting data Switch used Port 1 receiving data to enter Configuration Mode active Configuration Mode Power ON this LED has other functions also The front panel functions are mostly self explanatory The 4 20 OK LED illuminates when the current drawn by the 4 20mA analog sens
10. KD420 User Manual sTEMS UM 857185 v r y et owe wut 44 sara 0118 Cais Eg POWER suPPLY SYSTEMS Copyright 2004 2013 KK Systems Ltd No reproduction of any part of this document in any form is allowed without prior written permission from KKSystems Ltd All other copyrights and trademarks acknowledged Extract from Conditions of Sale Any electronic device or system can fail possibly resulting in the loss of valuable programs or data It is your responsibility to ensure that all such valuable material is backed up at all times We are not liable for any direct indirect or consequential loss caused directly or indirectly through the use of this product All our software is sold on an as is basis without a warranty of any kind We do not claim that this product is suitable for all potential applications It is your responsibility to verify that the product works in its intended application In the interest of progress we reserve the right to alter prices and specifications without prior notice Safety Warning The KD420 is not authorised for use in any situation where injury or death could result from its failure No interface should be connected to a dangerous potential Contents 1 6 KD420 OVEN 5 arr re att ut alvan aka aa a iku 1 1 1 Quick Start Guide nerneesvervesvernenversensersessersessvesessvesersvesessvenvesnenvesvenvennenernennense 3 1 2 Block DiagraM msmseereseanervesvasevvenvanevvenvsnev
11. are enabled in the ADC Settings tab every time there is any Modbus read and returns those values This will thus always return the most recent value The Sample every option is provided for applications where the fastest possible Modbus comms response is required but the analog parameter being measured does not need to be read each time This option reads one or both of the analog parameters those that are enabled in the ADC Settings tab at the specified interval and stores them in memory from which they can be retrieved by a read of the appropriate Modbus registers When the Sample every option is selected the A D conversion and any 50 60Hz noise filtering selected are done in the background The Modbus response time is thus reduced to little more than the serial comms time which depends primarily on the baud rate and the Version 1 0 Page 20 KD420 User Guide length of the parameter being read See the Performance description on the following pages for details An obvious example for the Sample every option might be temperature which can usually be adequately read once per second but if 100 KD420 units are connected to an RS485 bus then the highest Modbus comms performance is required in order to interrogate them all within a reasonable time Important The KD420 uses the Performance options in the ADC Settings tab to decide which of the two current and or voltage analog values should be read by the A D
12. e performs a single read with no averaging This setting will provide the fastest read times but without any attempt to eliminate mains generated noise on the input Version 1 0 Page 22 KD420 User Guide 5 2 2 2 Performance Options Normally these 3 options are all enabled and any Modbus read will populate all KD420 registers These options are provided for applications where Modbus comms performance and the analog reading rate need to be optimised concurrently When a Modbus Master reads the KD420 the total time will be the sum of these 5 items 1 Modbus Read command packet to the KD420 this depends mainly on the baud rate 2 A D conversion this takes 0 65ms for each analog channel If the 50Hz or 60Hz filtering is enabled add 20ms 17ms respectively for one analog channel or 40ms 34ms respectively for two 3 Formatting the return data this takes around 500us for the textual float formats and much less for the other data types 4 Modbus protocol related tasks e g enforcing the 3 5 byte dead time CRC checking and generation etc 5 Modbus Read return packet from the KD420 this depends mainly on the baud rate and the type of parameter being read At the commonly used baud rate of 9600 or any lower value there is little to be gained from changing the KD420 factory defaults because the Modbus comms time items 1 and 5 above dominates At the highest available baud rate of 115200 the comms time is
13. e port comms settings see below 40202 i 201 Port 2 KD420 Master port comms settings see below ki Port 1 KD420 Slave address 1 to 247 40204 Port 1 KD420 Slave sample interval 0 for on demand or interval between 203 1000 to 60000ms 40205 204 Version 1 0 Page 28 Port 2 KD420 Master slave device address to write to 0 to 247 KD420 User Guide BAG Port 2 KD420 Master number of retries 0 to 65535 on Port 2 KD420 Master timeout 0 to 65535ms 40208 Port 2 KD420 Master 4 20mA sample interval 0 to disable or 1000 to 207 60000ms ki Port 2 KD420 Master slave starting register for 4 20mA to write to 40210 209 Port 2 KD420 Master 4 20mA format see below 40211 Master 210 aster voltage sample interval 0 to disable or 1000 to 60000ms Master slave starting register for voltage to write to on Master voltage format see below 212 i r 5 ADC noise averaging 0 for 50Hz 1 for 60Hz 7 1 2 Communications Parameters Each communications port configuration is packed into a 16 bit holding register bit 15 14 13 12 11110 9 8765432 10 value SB P1 PO BW baud rate Where SB defines the number of stop bits 1 2 stop bits 0 1 stop bit P1 PO define the parity 0 off 1 even 2 odd The least significant LS 8 bits indicate the baud rate with values 0 to 20 corresponding to 30 to 115200 as follows bits 7 0 Baud Rate 0 30 1 37 5 Version 1 0 Page 29
14. ed from zero and with the Modbus function code determining the register type For example to read Modbus holding register 40001 you would specify register 0 and function code 3 read holding registers Similarly to read Modbus input register 30099 you would specify register 98 and function code 4 read input registers 5 2 4 Monitor Page This tab offers a debugging function KD420 Configuration File Port Firmware Help Modbus Slave Settings Modbus Master Settings ADC Settings Monitor ReadADCnow Voltage Current Within 4 20m Read every po ER seconds Version 1 0 Page 26 KD420 User Guide 6 Troubleshooting 6 1 1 KD420 Power Up Problems With a 24V power input there should be an output of approximately 20V between pin 4 and pin 6 of the 6 way Port 2 terminal block with pin 4 being the positive terminal The KD420 internal power supply will fail to start if the supply voltage rises from zero to the internal power supply startup voltage approximately 4V very slowly See the Power Requirements section for details If after power up the CFG LED enters a repeating pattern of n rapid blinks followed by a longer pause this indicates that a hardware fault has been detected by the KD420 power up test firmware This fault requires a return to the factory 6 1 2 KD420CFG EXE unable to connect Check the COM port is correct If using a USB to RS422 converter look in Control Panel Devices COM amp
15. much shorter particularly if only a 16 bit integer value is being read and there is a progressive improvement to be gained by using the KD420 features selectively Let s look at some actual cases The fastest comms option is to select the Sample every mode and then enabling and reading a single analog channel as a 16 bit integer at 115200 baud takes a total of 4 5ms i e 220 readings per second But the actual analog value will be updated only at intervals of 1 second or longer The 50 60H7 filter setting is available but does not affect the comms performance The Enable textual option has no effect on the timing in this mode The 2nd fastest option uses the Sample whenever mode no 50 60Hz filtering unchecking the Enable textual option and then enabling and reading a single analog channel as a 16 bit integer at 115200 baud takes a total of 6 3ms i e 150 readings per second Reading the same data as a 11 byte textual float takes 9 5ms i e 105 readings per second Version 1 0 Page 23 KD420 User Guide The above but at 9600 baud takes 25ms and 45ms respectively The slowest option at 9600 baud is with all factory defaults 50Hz filtering on and reading an 11 byte textual float which will take about 65ms for one channel Version 1 0 Page 24 KD420 User Guide 5 23 Modbus Master Settings The following tab configures the Modbus Master feature that enables the KD420 to write analog values into
16. or is inside those limits This LED also indicates A D converter activity this takes place approximately every second Only the general continuous state of this LED indicates whether the 4 20mA current is within its limits 1 4 Options Switch Options Switch Hullulullu Vi 234 This switch is currently unused Version 1 0 Page 5 KD420 User Guide 1 5 KD420 Analogue Input Circuitry 2 5 Zout 1 R AN 5V caz 2u2 16v RSS EA IC14A aK TLC2S2CD pe e CHL cat 3 aes 2u2 16V VREF HO 4 I 4 iki 1 CHA R54 SHO l 1 RSS 3 10k 85 4 4k CH3 cH4 RSS cHs amp 100K REE cHe 2 157 G VIN 33Vv cH7 2 2 En ad 39k compet RS cas IC14B C46 10k cas 1 n TLC252CD 1 n 1 n GND p L54148 ca gii RES 1 n 47R 1 15ePMm v RSS 2u2 16V EE R64 10k 4 IIN _ 22mA The KD420 has two analogue inputs voltage and current An understanding of the internal implementation of these is not usually necessary but may be useful in some applications 1 5 1 Voltage Input There are three particular aspects to be aware of The A D converter has a resolution of 12 bits i e 1 part in 4096 or 0 025 The measurable voltage input range is 33V to 33V If the voltage range you are measuring fully spans this range you will ge
17. oring 20V output Isolation Environmental Ventilation EMC compliance Dimensions Version 1 0 Receiver threshold 200mV typ differential Hysteresis 70mV typ 30V to 30V Input impedance 100kQ min Source impedance 100Q max for best accuracy Measurement accuracy 1 Absolute maximum input 60V to 60V 4mA to 20mA Sensing resistance 47Q Measurement accuracy 1 Absolute maximum current 50mA Within 17V to 23V with a 24V DC KD420 power input Current limited at 30mA typ short circuit protected 1 minute 3 way isolated Port 1 Port 2 Power In 64V PK tested at gt 1000V AC RMS 1 second All Port 2 features share a common ground pin 4 Operating temperature 20C to 50C Storage temperature 25C to 70C Relative humidity 0 to 90 non condensing Rail mounted KD420 must have a 50mm gap above and below Emissions EN50081 2 94 Immunity EN50082 2 95 29mm W x 114mm H x 97mm L approx in rail mounted position incl screw terminals Page 9 KD420 User Guide 3 Ports and Connections Reference Port 1 has two functions KD420 configuration and the Modbus RTU Slave connection It is accessible via the 8 way Port 1 terminal block or via the RJ 11 connector Only one of these two connectors may have connections to it at any one time The RJ 11 is provided for specialised applications where a custom cable is used Port 2 is used for the analog sensors and for a Modbus RTU Master mode
18. ort address dictated by the current configuration settings and the CFG LED will go out Tthe KD420 config mode can be terminated at any time by pressing the KD420 front panel button or by powering down the KD420 The KD420 will also enter config mode when it powers up If KD420CFG EXE does not communicate with the KD420 within 5 seconds the KD420 it will exit config mode and start up normally Version 1 0 Page 18 KD420 User Guide With the KD420 connected to the PC serial port and powered up start the KD420CFG EXE Configuration program from the shortcut in the Window Start menu You should see the following Reading configuration from KD420 Select the PC com port that the COM3 v KD420 is connected to or press 3 Demo Select the PC port that the KD420 is connected to or press Demo to explore the program without actually having the KD420 connected Version 1 0 Page 19 KD420 User Guide 5 2 1 Modbus Slave Settings The following tab configures functions applicable to Port 1 RS485 Modbus RTU Slave KD420 Configuration File Port Firmware Help a Modbus Slave Settings Modbus Master Settings ADC Settings Monitor Voltage and current sample interval Port 1 Configuration Baudrate 115200 Bits per word 8 Parity Sample ever o seconds O E Stop bits Modbus Slave Modbus Slave Address 1 The Sample whenever option reads one or both of the analog parameters those that
19. own in the Port 2 notes on page 15 Each terminator should be a resistor equal in value to the characteristic impedance of the cable which for good quality data communication twisted pair cables is around 110 ohms For best results a 10nF capacitor should be in series with each resistor this eliminates the DC loading of the termination resistor Version 1 0 Page 13 KD420 User Guide 3 2 Port 2 Analog Sensing The following diagram shows the two KD420 analog functions 4 20mA and voltage measurement The KD420 can operate both concurrently KD420 Thermocouple Transmitter with a 4 20mA Interface RJ 11 4 20mA Port e TC PORT 1 PORT 2 O HO Q 5 O Q 1 O O 4 2 O Voltage Measurement Input T O 5 2 O 30Vto 30V O 6 1O Pin 4 of the Port 2 terminal block should be earthed O 7 for best electrostatic and EMC performance Os EART I For powering the 4 20mA transducer the KD420 provides an unregulated 20V output which approximately tracks the KD420 supply voltage minus 4 volts on pin 6 Refer to the overall diagram on page 4 This supply is connected to the negative terminal of the transducer as shown in the above diagram and the positive terminal of the transducer is connected to the KD420 current measurement input pin 5 Important KD420 isolation is between Port 1 Port 2 and the power input The various features on Port 2 4 20mA voltage input and 2 wire RS485 a
20. re NOT isolated from each other and they share a common ground pin 4 Version 1 0 Page 14 KD420 User Guide 3 3 Port 2 2 wire RS485 Modbus Master KD420 can act as a Modbus RTU Master and can write the process values seen on the 4 20mA and or 30V inputs into specified registers of a single Modbus RTU Slave KD420 RJ 11 PORT PORT 2 O O O 2 5 O 3 1O 1 3 O 5 2 Q pt 6 1 O D O 7 O M Iles EARTH Note that Modbus communication in this mode Port 2 has priority over Modbus communication on Port 1 Normally this will never be seen but if the Slave device attached to Port 2 is very slow to respond this could cause long response times on Port 1 RS485 Bus Termination On cable runs exceeding around 300 metres two terminators should be connected as shown Each terminator should be a resistor equal in value to the characteristic impedance of the cable which for good quality data communication twisted pair cables is around 110 ohms For best results a 10nF capacitor should be in series with each resistor this eliminates the DC loading of the termination resistor Version 1 0 Page 15 KD420 User Guide Important KD420 isolation is between Port 1 Port 2 and the power input The various features on Port 2 4 20mA voltage input and 2 wire RS485 are NOT isolated from each other and they share a common ground pin 4 Version 1 0 Page 16
21. re internally interconnected They are not separate serial ports Use only one atany time Note normal KD420 configuration will also work over 2 wire RS485 because it is done by writing to Modbus registers However the firmware upgrade option needs RS422 4 wire which is also sometimes called 4 wire RS485 Port 1 can be built with an RS232 interface as a custom option contact factory Version 1 0 Page 11 KD420 User Guide 3 1 1 Port 1 KD420 Modbus Slave 2 Wire and 4 Wire The following diagrams show both 4 wire and 2 wire RS485 connections for Port 1 K A oooo sooo ADD q zs Nv p O000 ONS uw UND k l axl n en Sam gt N on on EZE gt sa z 2 C ano e gt ELI SEER as aja se 200 vXL Jr n 00 mae gt f gjer Q maes ar Eo H x vxl r soa imna oe i axe e N Mae of ht ss op yxi r n 50 POWER SUPPLY UNIT POWER SUPPLY UNIT Version 1 0 Page 12 KD420 User Guide RS485 Bus Termination On cable runs exceeding around 300 metres two terminators should be connected in the usual locations at both ends of the cable s An example of these is sh
22. t Accuracy We specify the voltage current measurement accuracy at 1 of full scale over the specified temperature range The actual factory calibration procedure is done at room temperature to around 0 05 Version 1 0 Page 7 KD420 User Guide 1 6 Power Requirements The power supply specification depends on the mode of operation The KD420 power input is 11 35V DC 2 watts max The constant power nature of the internal power circuitry means that at a higher supply voltage it will draw less current The following diagram shows the relationship 260 240 220 200 180 E 1460 The peak current which occurs around 4V 5 w can reach 600mA o w Input must reach the startup voltage a 100 typ 4V guaranteed 7V in less than 1 second 80 otherwise the power supply will not start up 60 40 20 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 Input Voltage V This means that a power unit needs to be rated at 300mA to handle the startup current even though the KD420 will draw much less at say 24V However the 20V output provided for powering a 4 20mA analog sensor is not regulated and approximately tracks the KD420 supply voltage minus 4V This output is intended to work with a 24V power input to the KD420 Version 1 0 Page 8 KD420 User Guide 2 Specification RS422 485 interface Voltage monitoring Current monit
23. t the full 0 025 resolution If however you are measuring a much smaller voltage range e g just 0 to 1V then the resolution will drop correspondingly to 1 6 The absolute accuracy of the measurement will be similarly affected The input resistance of the voltage input is not infinite it is about 140k ohms This means that if the source resistance of your voltage source is e g 1 4k ohms you will get a 1 measurement error When the voltage input has nothing connected to it it floats up to 1 25V This incidentally enables the sensing of e g an isolated relay contact connected between the voltage input and its analogue ground by connecting the relay contact across the KD420 voltage input Version 1 0 Page 6 KD420 User Guide 1 5 2 Current Input This is designed for standard 4 20mA transducer transmitters The current is passed through a 47 ohm resistor and the voltage drop across this resistor is measured using the 12 bit A D converter The measurable current range is 0 to 22mA and the 12 bit A D conversion gives a resolution of 0 025 i e 6uA The KD420 provides an unregulated 20V output which approximately tracks the KD420 supply voltage minus 4 volts for powering the 4 20mA transducer To use this supply connect it to the negative terminal of the transducer and connect the positive terminal of the transducer to the KD420 current measurement input Consult the wiring diagrams for details 1 5 3 KD420 Analog Measuremen
24. venessevvenessevvenessevvenesservesesservesesservennn 4 1 3 Front Panel Description a n nunan2b2as av m 5 1 4 Options 27 1 oi 9 RSS essens 5 1 5 KD420 Analogue Input Circuitry m smeemsensnevrersvesersvesvrsvenvenvenvesnensersensereens 6 13 1 Voltage Wboaisadikiokbudadusnkbdasbsnsudoskodkaduiawkh 6 155 22 Current DUE sanai daana aa Vit sulla viS a 7 1 5 3 KD420 Analog Measurement Accuracy a iiiaiiiiavissssssssssssssssnssansnna 7 1 6 Power RequirementS numseusvsevvesvaservesvrservesvrsevvenvssevvenersevvesessevvesesservesesservennns 8 Specification 2 222ai0isniniskssananandnanaiainununun innuak usknunu ns u ani unsdunnninning 9 Ports and Connections Reference 10 3 1 Port 1 KD420 Configuration u nm suserrsnevrsnevsersvesersvesvesvesvesvenvernensersenserne 10 3 1 1 Port 1 KD420 Modbus Slave 2 Wire and 4 Wire 2ssuvsasavivaaai 12 3 2 Port 2 Analog Sensing meeseesvesvesrernesrersessersessensersvesersveseesveneesnenvesnensernensense 14 3 3 Port 2 2 wire RS485 Modbus Master sssssssssssssssssssssssssesssesessseeesteass 15 MOUNTING iiini alla 17 Configuration sssini een 18 5 1 Installing KD420 Configuration Software n seseeneesersvesvenvesvervenvervesversenser 18 5 2 Using KD420 Configuration Software n semnrneenenverersvesvesvesvervesvernensersenser 18 5 2 1 Modbus Slave Settings oo cseeesesseeesesseeseeesseeseeesseeseeesseeseeessneneeesseeees
25. via Modbus RTU SLAVE registers In this case the following data formats are presented concurrently 40000 Current in 4 20mA range logical value 1 yes 0 no 40001 Current as a 16 bit unsigned integer in microamps 0 to 64000 40002 Current as a 32 bit IEEE float point value big endian mA 2 registers 40004 Current as above little endian 2 registers 40006 Current as a null terminated textual float 00 000 mA 8 registers 40020 Current as above E notation 0 000e 00 11 registers 40101 Voltage as a 16 bit signed integer in millivolts 32000 to 32000 40102 Voltage as a 32 bit IEEE float point value big endian V 2 registers 40104 Voltage as above little endian 2 registers 40106 Voltage as a null terminated textual float 00 000 V 8 registers 40120 Voltage as above E notation 0 000e 00 11 registers 2 The KD420 writes them into an RS485 Modbus RTU SLAVE device A Modbus register in the KD420 is used to configure the following parameters e Starting register number to write to e _ Selection of which parameter and data format to write e Update interval 1 60 seconds Version 1 0 Page 1 KD420 User Guide DOODO EJE YWOOE Od AGE Z Jase G8PSY 3IM Z AlddNS HIMOd ALH Snep AAS NIH NPON SNqpPON G8YSE SIM y JO S08JI JU YUZ E UM J JUISUeJ ajdnooowey EH THI aveau ENES fouy NLY snapo G8YSY IM Z HALSYN SNEON
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