Serial to analog converter
Contents
1. followed by a newline Then give the patterns on the next line s in the control string If we have a Vaisala style message belie Be F OR1 Dn 236D Dm 283D Dx 031D Sn 0 0M Sm 1 0M Sx If the delimiter is or or it can t be 2 2M mentioned directly in the control string because We can pick Dm and Sm conveniently note that those characters have a special meaning to the the control string has multiple rows parser They must be escaped by preceding them ares with a A message separated by s would be Dm 21 handled by a control string like this Sm 2 SLSE S2E S3S S4S Ignoring fields If we have a message like 10 20 30 40 50 60 70 80 And want to read in the third and fifth field only accept several different kinds of messages and enter the following control string 7470 splits the message at each comma Then it applies each control string row to each comma split field Different messages Beginning from firmware version 4 0 7470 can pick different values from each For example 15 NMEA 0183 messages SGPGGA 092750 000 5321 6802 N 00630 3372 W 1 8 1 03 61 7 M 55 2 M 76 GPGSA A 3 10 07 05 02 29 04 08 13 1 72 1 0 3 1 38 0A SGPGSV 3 1 11 10 63 137 17 07 61 098 15 05 59 2 90 20 08 54 157 30 70 Want to pick the third and the fifth field of the 16 SGPGGA message latitude and longitude plus the fourth field of SGPGSV number of satellites Two rows of control string will do2. D1 DO should be a twisted pair Supply voltage The supply voltage is connected according to the picture There is a polarity protector diode Detachable connectors The green connector blocks are detachable to make connecting easier They accept up to 2 5mm wires Jumpers 7470 V1 2 JP1 oO MP3 JP2 T JP4 ee ee ee ee To set up the jumpers the enclosure has to be opened Detach the device from the DIN rail and insert a flat bladed screwdriver between the black and grey parts of the enclosure and lever carefully The jumper JP1 forces the RS 232 485 port to use SCL protocol 9600 baud address 0 This is to enable configuring the device without using a programming cable When the jumper is removed this port uses the settings defined in the configuration menu The jumper JP2 is for programming the microcontroller at factory The middle pins must be shorted with a jumper The jumper JP3 is not used yet The jumper field JP4 selects RS 485 bus options see the table below The blue grey jumpers are not required for operation but indicate a place for spare jumpers This table applies only to the PCB version V1 2 JP4 Configuration Usage Nothing The middle devices on the bus or when the bus is short Factory setting Terminated The first and the last device of the bus Polarized The middle devices on the bus when there is no other device to give the polarization fail safe bia
3. it GPGGA 1 2 GPGSV 3 SCL MASTER When there is no PC or any other device available that could master the bus i e command the bus devices one 7470 can be configured to act as a master It can read values from other devices on the bus and redirect them to other devices The four analog outputs of the mastering 7470 are available too Fetching Fetching means querying values from the other devices on the bus These devices are most often transmitters measuring temperature voltage current etc Also Nokeval RTR970PRO radio receiver can be read 7470 uses SCL command MEA CH or MEA SCAN for this The fetch operations are configured in the menu Ser Master Fetch There may be up to eight fetch groups One group corresponds to one serial command sent to another bus device and it may fetch up to eight values The first setting Groups is used to select how many fetch groups are needed Within each group there are three settings Addr defines the serial bus address of the other device First tells from which channel to read on the other device and Num tells how many channels to read Putting 7470 is able to send or put the fetched values to other devices on the bus E g one 7470 can read 16 channels from a temperature transmitter and then deploy the values to other 7470 s to have more than 4 analog outputs 7470 uses SCL command OUT CH or OUT SCAN for this Up to eight put groups may be defined Each
4. simple like this 100 0 200 0 300 0 400 0 lt cr gt lt 1 gt 7470 is able to handle it with the classic parser The fields may be separated with one comma one semicolon one tabulator or one or more spaces If there is non numerical characters within the field 7470 will ignore them until a numerical character 0 9 minus decimal point is encountered It will then read in the figure until a field separator or any other non numerical character is encountered So 7470 is able to read Custom parser If the message is not field separated delimited by a comma space semicolon or tabulator the custom parser has to be used Also if the transmitter sends several different types of packets and only one of them is to be picked by a certain 7470 the custom parser is needed Prior to firmware V3 4 7470 expects 8 data bits and none parity 8N1 but it discards the most significant bit So it accepts 7E1 and 701 too but does not check the parity Beginning from firmware V3 4 7470 can be configured for parities 801 8E1 and 8N2 at Conf Ser Parity Selecting 8N1 accepts 8N1 7E1 and 701 by discarding the most significant bit There are two parsers algorithms that split the Ascii message to fields and tries to find numerical values there classic and custom The classic parser does not allow any configuration but it is simple to use It can be used when the message contains values separated by spaces commas semicolo
5. 0 11 1V typ Maximum load 5 kilo ohms Short circuit protect yes 15mA Response time Output reaction time0 40ms Output timing 4 7ms reaction 0 40ms 67 of end value 12 5ms reaction 0 40ms 93 of end value 150ms reaction 0 40ms 100 of end value Min 3 5 characters Max 10ms or 3 5 characters Response time Termination Externally with a resistor or internally with a jumper Isolation Functional isolation 50 VAC 120 VDC Protection IP20 Mounting 35 mm DIN rail Weight 125g EMC EN 61326 1 2013 21
6. From BYTE Unsigned 0 32 2015 2015 Conf Ch 3 Range ENUM See table E1 2016 2017 2016 2017 Conf Ch 3 Lo FLOAT Signed 2018 2019 2018 2019 Conf Ch 3 Hi FLOAT Signed 2020 2020 Conf Ch 3 Limit BOOL 2021 2021 Conf Ch 4 From BYTE Unsigned 0 32 2022 2022 Conf Ch 4 Range ENUM See table E1 2023 2024 2023 2024 Conf Ch 4 Lo FLOAT Signed 2025 2026 2025 2026 Conf Ch 4 Hi FLOAT Signed 2027 2027 Conf Ch 4 Limit BOOL 2028 2028 Conf Ser Mode ENUM See table E2 2029 2029 Conf Ser Baud ENUM See table E3 2030 2030 Conf Ser Parity ENUM See table E4 2031 2031 Conf Ser Addr BYTE Unsigned 0 127 2032 2032 Conf Ser Parser ENUM See table E5 2033 2048 2033 2064 Conf Ser String STRINGZ Len 32 or 64 2049 2065 Conf Ser Stime BYTE Unsigned 0 60 2050 2066 Conf Ser DelayResp BOOL 2051 2067 Conf Ser Master Fetch Groups BYTE Unsigned 0 8 2052 2068 Conf Ser Master Fetch 1 Addr_ BYTE Unsigned 0 255 2053 2069 Conf Ser Master Fetch 1 First BYTE Unsigned 0 255 2054 2070 Conf Ser Master Fetch 1 Num_ BYTE Unsigned 0 8 2055 2071 Conf Ser Master Fetch 2 Addr_ BYTE Unsigned 0 255 2056 2072 Conf Ser Master Fetch 2 First BYTE Unsigned 0 255 2057 2073 Conf Ser Master Fetch 2 Num_ BYTE Unsigned 0 8 Conf Ser Master Fetch 3 Addr 2058 2074 Each group increases register BYTE Unsigned 0 255 address by 3 2076 2092 Conf Ser Master Put Groups BYTE Unsigned 0 8 2077 2093 Conf Ser Master Put 1 From BYTE Unsigned 1 32 2078 2094 Conf Ser Master Put 1 Addr BYTE
7. Unsigned 0 255 2079 2095 Conf Ser Master Put 1 First BYTE Unsigned 0 255 2080 2096 Conf Ser Master Put 1 Num BYTE Unsigned 0 8 Conf Ser Master Put 2 From 2081 2097 Each group increases register BYTE Unsigned 1 32 address by 4 2108 2124 Conf Ser Master Put 8 Num BYTE Unsigned 0 8 Table E1 Table E3 Value Range 5 T Value Baud 1 0 10V p 300 2 0 20mA 1 em 3 4 20mA 2 1200 3 2400 4 4800 Table E2 Ica Value Mode 6 19200 0 SCL 7 38400 1 Modbus 8 57600 A Ascii 9 115200 3 SCL Master 10 230400 4 Metso Hart 13 Table E4 Value Parity 0 8E1 1 801 2 8N2 3 8N1 Table E5 Value Parser 0 Classic 1 Custom ASCII MODE Some weighing and weather transmitters are able to output their readings in Ascii which means human readable data terminated by a CR or LF or both 7470 can receive and interpret most of this kind of messages The transmitter has to be configured to send its readings automatically 7470 does not send query commands 7470 will not respond to the Ascii packets Several 7470 s can be parallel connected to a RS 485 bus to receive the Ascii messages Each one can be configured to handle a different part of the message The Ascii mode does not use any addressing nor checksum However some addressing may be realized with the custom parser see below Ascii packets can be sent with any terminal software e g PuTTY Classic parser If the message is
8. User manual 2015 05 11 Firmware V4 0 PCB V1 2 7470 Serial to analog converter VOSHSHSEQNSES Nokeval INTRODUCTION 7470 is a serial bus controlled analog output unit It provides four mA or V outputs that can be controlled via an RS 232 or RS 485 bus As a slave it supports Nokeval SCL Modbus RTU and Ascii protocols Alternatively it can function as a SCL Master querying other devices Analog output ranges include 0 20mA 4 20mA 0 5V and 0 10V 7470 needs a 24 VDC supply voltage The analog outputs are not galvanically isolated from the power supply or each other They share the common negative wire However the serial bus is galvanically isolated For using 7470 with Vaisala weather stations a separate application note is available How to use this manual The chapter Installing shows how to connect this device and set the jumpers It also tells how to access the configuration settings The settings itself are described in chapter Configuration menu Each of the available serial modes are described in the chapters of their own Table of contents aage UCU ayes cen s EEE E ys aa vetadeSdeuenean vet beedeacsvbnaeesitusidnctesnaccecbounseysdeusasiedseceevaceseveeness 2 MVS tea NAS AE E T ateevta tide celcbed carve E 3 CONF UAT ON MSM esas e e E e E E Ae EERE E 6 Troubleshooting sssini enano e aaa ena aaa a aa eae e ae E E Eea aeiia EEEE Taia 9 SCHProtoco leain e E E E n a E A E A a ETER 11 Modbus Protocol sse a a e
9. a a st ies a AEE 12 viol i ag lole Etraon a E E A A E A 14 SCL VE E E a E E a A E E A E 17 Metso Hart etashse ce cecees a teien ienee eai EE E EEEE aE a E a aaeeea aa E E OE E REEE iE ENEE 18 Nops aiene ere E E E E EE E E EEE E EEE E ee 20 SS CITI CALI ONAS sra e E E E E A E a E E aes dase a 21 Manufacturer Nokeval Oy Tel 358 3 3424800 Rounionkatu 107 Fax 358 3 3422066 FIN 37150 Nokia www nokeval com Finland Mounting INSTALLING This transmitter is intended to be mounted on a 35 mm DIN rail The position is free Connections Out1 Out2 Out3 Out4 cee S57 Wl a hs O O e E E E E lt lt L x x SOs E gt E gt ES za o Db a Common Common lt TxD gt RxD RS 485 RS 232 Analog outputs The upper row provides 4 analog outputs The mA and V outputs on a single channel can t be used simultaneously The analog output commons are internally interconnected with each other and the power supply common Serial buses 7470 provides RS 485 and RS 232 buses There is no need to change anything to select which bus to use but because both buses share a connector block to prevent attempts of simultaneous use the connector block is meant to be moved to the RS bus that is used RS 485 bus should be used with ground wire common between the devices whenever possible If not possible JP4 should be set to the 2 wire configuration See the next JP4 table and 2 wire section The data pair
10. command to an external device Available only at POL port The string after the command C is sent to the RS 232 485 port terminated with CRLF The port has to be configured for Ascii protocol See also command G G Requesting Ascii packets received from the RS 232 485 port Returns the packets from a string buffer When all is read out returns an empty response This command is available at the POL port only PORTID Returns 1 if the command is given in RS 232 485 port and 2 if commanded from the POL port For factory testing 11 MODBUS PROTOCOL Commands e 3 Read Holding Registers read current configuration e 6Write Single Register change the configuration and control the outputs e 16 Write Multiple registers change several registers e 17 Report Slave ID device type query e 109 Meku Mekuwin uses this e 110 Nopsa Nopsa commands Maximum Modbus frame is 150 bytes Command 17 returns 0x11 lt bytecount gt 0x00 OxFF and then 7470 V4 0 A012345 for example Data types e BOOL Off On setting O off 1 on on the lower byte e BYTE Single byte value Only the lower least significant byte used e WORD 16 bit value Most significant byte first e ENUM List of options e FLOAT 32 bit floating point IEEE 754 Least significant word first Inside the word most significant byte first Holding registers The analog outputs can be controlled via registers 0 7 in IEEE 754 format or alternatively via regi
11. e the high end signal Limit Limits the analog output within the nominal range If enabled the analog output will not exceed its end points e g the 4 20mA output will not go below 4 mA nor above 20 mA even if requested to If the safety timer expires the output will go to O mA or O V despite of this setting Ser submenu The Ser menu settings affect the RS 232 485 port only The POL port uses always SCL protocol 9600 baud Mode Serial bus protocol and mode e SCL slave Nokeval SCL protocol 7470 may be controlled using SCL commands like OUT CH and OUT SCAN See chapter SCL protocol e Modbus Modbus RTU protocol 7470 may be controlled using write holding register and write multiple registers functions All the configuration settings are also accessible See chapter Modbus protocol e Ascii 7470 accepts simple messages with no proprietary protocol The messages have to end with CR LF or both See chapter Ascii mode e SCL Master 7470 acts as a serial bus master sending commands to the other devices on the bus Only one device should be a master on a single bus In this mode 7470 can read serial bus transmitters and Nokeval RTR970PRO radio receiver without a PC or another master See chapter SCL Master e Metso HART Hart style protocol See chapter Metso HART Baud Baud rate 300 115200 All the devices on the bus must have the same baud rate Factory default is 9600 Parity Applicable for Modbus and Ascii only O
12. group corresponds to one serial command sending up to eight values to another device on the bus The first setting Groups is used to define how many put groups are needed Within each group there are four settings Addr defines the bus address of the other device First tells the first channel on the other device that the There must always be exactly one master on the bus If there is no master at all all the devices only listen If there are two or more masters they will collide The master does not have an address of its own Only the slaves use an address Every slave must be configured to a different address The values fetched with group 1 are stored in the internal channels 1 onwards The values fetched with group 2 are stored in the next free internal channels etc E g if group 1 fetches 4 channels and group 2 fetches another 4 the values will be placed in internal channels 1 4 and 5 8 respectively The fetches may be configured freely It is allowed to do several fetches from the same bus device e g to fetch more than 8 values from a 16 channel transmitter Every time a fetch is done successfully the safety timers of the updated internal channels are reset If some channel is not updated for a time specified in Stime setting in the Ser submenu that channel will be considered expired If an analog output is following that channel it will be pulled to O mA or OV values are sent to Num tells how many
13. is engaged the minimum interval between the command and response is increased to 25 ms In SCL Master mode setting DelayResp on makes the 7470 to keep a 5 second pause between each full cycle of sending master commands This is useful with radio modems to not block the whole radio band If DelayResp is off 7470 will send commands without pauses Master The submenu used to configure how this device acts as a SCL Master See chapter SCL Master TROUBLESHOOTING Diagnostic messages 7470 can detect some abnormalities The messages can be viewed with Mekuwin or observed on the red LED inside the enclosure Message Blinks Explanation Stime exceeded 2 Safety timer has expired At least one output has been dropped to 0 mA or 0 V because its safety timer has been expired due to not being updated within the time defined in Stime setting No serial 3 No proper packets are received from the RS 232 485 port within the last 30 seconds Serial error 4 Invalid data has been received from the RS 232 485 port wrong protocol baud rate parity incorrect checksum for example LED The red LED inside the enclosure blinks status information To see the LED the enclosure has to be opened as guided in chapter Jumpers If everything is well the LED blinks shortly every 2 seconds When there are active diagnostic messages the LED blinks a series of as many blinks as stated in the table above e g 2 blinks and a pa
14. lue of these numbers has to be between 0 and 100 inclusive in order to be accepted if they are not they are discarded and the safety timer is not reset An example of the whole frame in hexadecimal Bae al ee i Gl E eee oe one eee Soe oe e Mf six lowest bits of manufacturer id and most significant bit set for primary master e T device type always 01h e ID 000000h the address selected in the configuration e C command e Bc byte count e LP longitudinal parity The device will respond Possible errors are e Longitudinal parity error status bytes 88 00 in hexadecimal e Command not implemented 40 00 e Incorrect byte count 05 00 e Buffer overflow 82 00 If the analog outputs are requested to go outside their range they will go as far they can Limit off or to the end of the range Limit on No error is given NOPSA Nopsa is a simple language intended for data interchange between devices The data is transferred in binary format making it ideal for machine to machine communications 7470 allows Nopsa commands to be sent over SCL and Modbus protocols Nopsa is specified in a separate document available on request This device supports the following Nopsa commands e 1 0 Type query returns 7470 e 1 1 Software version query returns V4 0 e 1 2 Serial number query returns A012345 e 1 3 Description query returns Analog output unit e 1 32 Meku configura
15. ns or tabulators When more control is needed the custom parser gives more freedom this message A 100 0 B 200 0 C 300kg D 400m2 E 0 Reading of 100 0 is read to the internal channel 1 200 0 to channel 2 etc m2 is ignored because one numeric portion has been already found in that comma separated field The maximum length of a message is 150 characters Up to 32 fields may be read in to the internal registers The analog outputs can be programmed to follow any of these internal registers The custom parser is configured with one control string that contains instructions to 7470 how to handle the message The control string consists of the following parts Part Name Description Replace string ignored too Any number of characters in the message will be ignored until a character following the is encountered in the message E g will ignore all characters in the message until a is found The will be Replace character One character will be ignored in the message Several s may be used Part Name Description contiguously to ignore more characters 1 Pick Picks a value to the internal channel 1 from the message Will pick until a character following the 1 is encountered in the message or the message ends E g 1 will pick characters until a comma is found in the message The comma will be ignored then The channel number can be 1 32 FS Set field separato
16. ol 9600 baud and address 0 or 126 CONFIGURATION MENU DelayResp Master Master The menu is arranged hierarchically The first level contains four submenus one for each analog output and a serial communications submenu Some of the settings are hidden when they are not used Ch submenus Analog output Serial bus Internal channels OUT CH 1 100 From 1 4 20mA Each analog output is configured independently From 7470 contains 32 internal channels storing the variable values received via the serial bus The channels are numbered 1 32 The From setting is used to select which internal channel is used to control each analog output Most often the values are sent to internal channels 1 4 and the first analog output channel follows the first internal channel etc However sometimes it may be useful to be able to have several analog outputs following the same internal channel It is advisable to set From 0 on unused channels Otherwise the LED will blink an error code on these channels This is possible beginning from firmware V4 0 Range The analog output range selection Options are e 0 20mA e 4 20mA e 0 5V e 0 10V Lo Hi Analog output scaling When the channel value controlling the analog output corresponds to the Lo setting the output will give its low end signal e g 4 mA if the range is 4 20mA Likewise the value of Hi will giv
17. ptions e 8N1 with Ascii accepts 7E1 and 701 too e 8N2 e 8E1 recommended for Modbus e 801 Addr Serial bus address of this device in SCL slave Modbus and Metso HART modes e In SCL mode legal values are 0 123 In addition to the selected address 7470 will always respond in address 126 When the POL plug is inserted in the front panel 7470 will respond in any address e In Modbus mode legal values are 1 247 e In HART mode legal values are 0 127 Parser Parser selection in Ascii mode Options are e Classic Non configurable parser equivalent to 7470 firmware versions 1 x e Custom Configurable parser See chapter Ascii mode String Parser control string in Ascii mode when Custom parser is selected See chapter Ascii mode Stime Safety timer Defines a safety time in seconds If some of the internal channels see Ch From on page 6 is not refreshed within this time the safety timer will expire on that channel An analog output configured to follow that channel will then go low 0 V or mA This works in every mode The time can be selected from 1 to 60 seconds in 1 second steps To disable the safety timers set value of 0 here DelayResp When some other device sends a SCL command to the 7470 it will process the command and send a response as soon as possible but not earlier than 3 5 characters time from the end of the command At 9600 baud this minimum time corresponds to 3 6 ms If DelayResp
18. r Defines a field separator Once defined 7470 will split the message to fields at every separator and apply each control string row to each field any other Match If the control string contains other characters the input string must have equivalent characters or the parser will exit This feature can be used to pick a certain type of packet if the transmitter sends several different packets When the parser exits all the fields handled before exiting will be still used Some examples will clarify things up Simple message Consider a message like 10 20 30 40 To read this in enter a control string 31 2 3 4 A comma separated message could be handled by the classic parser too Custom delimiter x r r 1 r r 2 Looking for a pattern A message containing something interesting in the middle e g a net weight G 2334 4 N 1999 9 T 0334 5 The following control string will search the net weight identifier N and pick the value N S1 Field separators If the message is arranged to fields separated by some character it is advisable to let the 7470 to If the message is separated delimited with e g handle the message field by field This is not slashes like this 10 20 30 40 lt cr gt The control string that can interpret this to the four first channels possible before firmware version 4 0 The field separator is defined by writing e g FS in the control string
19. sing idle voltage Used typically when 7470 acts as a bus master Ser Mode SCL Master and is not the first nor the last device Terminated The first and the last device on the bus when there is no other device to give the and polarized polarization fail safe biasing idle voltage Used typically when 7470 acts as the bus master Ser Mode SCL Master and is the first or the last device 2 wire When RS 485 common ground wire is not available g ag E TRE MEET Configuring The 7470 can be configured with a PC or with a hand held programmer PC configuration with a programming cable Two types of programming cable are available e POL RS232 for RS 232 port of the PC e DCS772 for USB port of the PC The software used is Mekuwin available for free The cable is attached in the 3 5mm jack marked as POL 7470 has to be powered up In Mekuwin select the adequate serial port SCL protocol 9600 baud and address 0 or 126 Connect The contents of the configuration menu are explained in chapter Configuration menu For details of Mekuwin itself refer to the Mekuwin manual PC configuration via serial bus If a programming cable is not available 7470 can be configured via RS 232 485 port Configuring is possible only when 7470 uses SCL or Modbus protocols If 7470 is configured for any other protocol or the serial settings are not known it is possible to use jumper JP1 to force the RS 232 485 port to use SCL protoc
20. sters 1000 1003 in regular 16 bit signed integer format These correspond to the internal registers 1 4 see page 6 The configuration settings are accessible in register 2000 onwards When the configuration is changed the changes are automatically stored in the EEPROM If the serial configuration is changed via Modbus the new settings do not affect until powered down Do not write excessively many settings in one transaction Register FW3 x Register FW4 x Name Type Values 0 1 0 1 Ch1 FLOAT Signed 2 3 2 3 Ch2 FLOAT Signed 4 5 4 5 Ch3 FLOAT Signed 6 7 6 7 Ch4 FLOAT Signed 1000 1000 Ch1 WORD Signed 1001 1001 Ch2 WORD Signed 1002 1002 Ch3 WORD Signed 1003 1003 Ch4 WORD Signed 2000 2000 Conf Ch 1 From BYTE Unsigned 0 32 2001 2001 Conf Ch 1 Range ENUM See table E1 2002 2003 2002 2003 Conf Ch 1 Lo FLOAT Signed 2004 2005 2004 2005 Conf Ch 1 Hi FLOAT Signed 2006 2006 Conf Ch 1 Limit BOOL 2007 2007 Conf Ch 2 From BYTE Unsigned 0 32 2008 2008 Conf Ch 2 Range ENUM See table E1 12 2009 2010 2009 2010 Conf Ch 2 Lo FLOAT Signed 2011 2012 2011 2012 Conf Ch 2 Hi FLOAT Signed 2013 2013 Conf Ch 2 Limit BOOL 2014 2014 Conf Ch 3
21. tion commands over Nopsa e 1 36 Fetching a delayed response Used with the Route commands e 2 2 Control the analog outputs Floating point format only supported e 2 3 Information about the outputs The outputs are named Out1 Out4 e 3 0 Routing commands Allows routing SCL Nopsa commands from the POL port to the RS 232 485 bus devices mainly for configuring them through the 7470 Available only with the SCL Master protocol The route address defines the target device address on the bus 7470 returns always a delayed response PROCESSING and the final response is then polled with Nopsa command 1 36 e 3 1 Information about the routing capability of this device 20 Outputs Channels Isolation mA output Ranges Accuracy at 25 C Operating range Maximum load V output Ranges Serial ports Buses Protocol Baud rates General Temp stablility DA conversion Supply voltage Curr consumption Oper temperature Dimensions SPECIFICATIONS 4 outputs Non isolated from each other and power Common negative wire 0 20mA and 4 20mA 0 1 of range 0 22mA typ 600 ohms 0 5V and 0 10V RS 232 RS 485 Nokeval SCL Ascii Modbus RTU 300 600 1200 2400 4800 9600 19200 38400 57600 115200 baud 50ppm C of range 12 bits resolution 4096 18 28VDC 30mA 120mA 0 55 C i C000000000006 106 86 999900000009 Accuracy at 25 C 0 1 of range Operating range
22. ure the D1 to DO voltage at the other end of the bus It should match With RS 232 it is advisable to measure the Tx and Rx voltage against the common Both of them should idle 3 to 15V SCL PROTOCOL A more detailed description of the Nokeval SCL protocol can be downloaded from Nokeval WWW site This unit understands the following SCL commands TYPE Returns the model name and software version 7470 V4 0 without the quotation marks SN Returns the serial number e g A012345 OUT CH 1 100 0 Sends a value of 100 to the internal channel 1 Channels 1 9 are writable this way although normally up to four of them are used since 7470 has four analog outputs About internal channels see the From setting on page 6 7470 will return an empty response ACK ETX BCC Acceptable characters are 0 9 minus decimal point and leading or trailing spaces A deliberately invalid value NaN can be expressed as several minus characters to steer the analog output to 0 V or 0 mA to indicate something is wrong OUT SCAN 1 4 10 20 30 40 Sends several values to the internal channels 1 to 4 give the first and the last Maximum of 8 values can be sent with one command channels 1 9 can be accessed this way The values are separated with one or more spaces MIN xxxxx Commands used by the Mekuwin configuration software N XXXXX Nopsa commands encapsulated in SCL See chapter Nopsa C XXXXX Sending a
23. use tells that the safety timer has expired If there are several messages active they will be blinked one after another Monitor With the Monitor function of Mekuwin some of the internal values of 7470 can be observed e Ch1 Ch32 indicate the channel values They are updated by sending data on the RS 232 485 bus These indicate the latest received value An expired safety timer does not affect these e Out1 Out4 indicate the electrical analog output value in mA or V An expired safety timer drops the analog outputs to zero so these will go to zero too e RecvString is the latest received packet It is useful for troubleshooting and for investigating the structure of the message Simulation The Ch1 Ch32 items in Mekuwin monitor can be manually edited for testing purposes The consequences are the same as when sending packets on the serial bus The safety timer is applied for the manual input too Electrical If the LED is alive the supply voltage is present but it might be worth checking its correct value since a too low supply voltage can cause various problems If RS 485 is used use a multimeter to measure the voltage between D1 and DO lines It should be positive between 0 2 and 5 volts If it is zero the bus may be short circuited or it is lacking a polarization also known as fail safe bias or idle voltage which is usually provided by the bus master If the voltage is negative the bus wires may be crossed Meas
24. values to send From defines the internal channel of this 7470 that provides the first value to be sent For example if configured as follows e From 5 e Addr 2 e First 1 e Num 4 The mastering 7470 will send values from its internal channels 5 8 to the channels 1 4 of the device on bus address 2 If some internal channel has expired dashes will be sent to indicate fault METSO HART 7470 can be controlled using the Hart protocol on RS 485 bus Supported command set is minimalistic commands 0 and 206 As always with Hart odd parity 801 is used 7470 accepts only the long address not the polling address Manufacturer ID is 47d or 2Fh Valmet Metso Device type byte is 01h The two most significant bytes of the address are zero and the least significant is selectable on the configuration menu Ser Adadr selectable 0 127d This device needs 2 preambles and sends 5 If no command is received within 15 seconds then the serial port will be reset This is repeated every 15 seconds until a command is received Command 0 Read Unique Identifier This command is useful to see the device exists on the bus Command 206 Controlling the outputs The analog outputs are controlled with this command After the command byte 206d or CEh comes one byte indicating the number of data bytes It must be 16d After that comes 32 bit floating point numbers in IEEE754 format the most significant or exponent byte first The va
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