SRW01 - CommunicationModBus-RTU (v.4.0X)
Contents
1. 2 1 MODBUS RTU uu u u den ben u E Gu uuu Ous be eee as 11 2 DT 088 Sak ahua ae 1 2 13 Power Supplyu uu E AE A EEE E O AR 12 2 2 CONNECTION WITH THE 220 2 222 427 2 24 2 09 SEKA TUN a s 12 2 3 MODULE CONFIGURATION uu u E AA A SOS 12 2A STATUS INDICATION vatten ee 12 RELAY PARAMETERIZATION 3 P202 OPERATON MODE she 13 220 LOCAL REMOTE 5 1 2 Su aS Sw asus 13 P232 REMOTE COMMAND SELECTION 13 P277 DIGITAL OUTPUT OT FUNCTION uu u u u 13 P278 DIGITAL OUTPUT 2 0 0 0 0 6 asas 13 P279 DIGITAL OUTPUT FUNCTION 13 280 DIGITAL OUTPUT O4 00 00 0 0 6 13 P281 DIGITAL OUTPUT 5 0 00 0 00 62. 14 P282 DIGITAL OUTPUT 2 KONAS RAAS 14 P283 DIGITAL OUTPUT 07 0 0 0 0 0 0 0 00 6 14 284 DIGITAL OUTPUT 00 0 0 0 00 6 14 P313 COMMUNICATION ERROR 1 1 4 14 P3 1 4 2 SN 15 725 COMMUNICATION 55 22 4 1 174 214414 15 P726 DEVICENET MODBUS BOARD BAUD 2 2 2 16 P770 READING PROGRAMMABLE PARAMETER 1 16 P771 READING PROGRAMMABLE PARAMETER 2 16 P772 READING PROGRAMMABLE PARAMETER 43 1 16 P773 READING PROGRAMMABLE PARAMETER 4 1 16 P774 READING PROGRAMMABLE PARAMETER 5 1 1 16 P775 READING PROGRAMMABLE PARAME
3. 770 Reading Programmable Parameter 1 771 Reading Programmable Parameter 2 772 Reading Programmable Parameter 3 773 Reading Programmable Parameter 4 P774 Reading Programmable Parameter 5 P775 Reading Programmable Parameter 6 Adjustable 0 to 999 Factory default 0 Range Properties Sys rw Description These parameters allow the user to via network program the monitoring of up to six parameters in a sequence The contents of the parameters are shown in the parameters P780 to P785 P780 Value of the Reading Programmable Parameter 1 781 Value of the Reading Programmable Parameter 2 782 Value of the Reading Programmable Parameter 3 783 Value of the Reading Programmable Parameter 4 P784 Value of the Reading Programmable Parameter 5 P785 Value of the Reading Programmable Parameter 6 Adjustable 0 to 65535 Factory default 0 Range Properties RO Description Present the content of the parameters defined on P770 to P775 For example P770 5 In this case the content of parameter P005 frequency out of range will be sent via network to the parameter P780 6 Modbus RTU Commands Used at the SRW 01 4 MODBUS RTU COMMANDS USED AT THE SRW 01 The following commands functions were implemented in the Modbus RTU protocol of the SRW 01 smart relay following the specifications found at www modbus org Modb
4. 2 Table 2 1 8 wire plug in terminal strip 2 pinout for the Modbus RTU interface Protection Earth shield RD RD Not used by Modbus Table 2 2 DB9 XC15 connector pinout for the Modbus RTU interface Kees ae XC15 Function Not used by Modbus Not used by Modbus B Line Modbus PE Protection Earth shield NC not connected 11 Accessory Kit ATTENTIONI Terminal strip XC2 pin PE must obligatorily be connected to a protective earth even if the used connector is DB9 XC15 2 1 3 Power Supply The SRW 01 Modbus RTU intertace does not require external power supply The communication module already has an internal isolated power supply 2 2 CONNECTION WITH THE NETWORK The following point must be observed for the connection of the relay using the Modbus RTU interface M The use of specific Modbus RTU network cables is recommended M The grounding of the cable shield is at only one point in order to avoid current loops M Switch on the termination resistor DIP switch only at the extremes of the main bus even if there are derivations 2 3 MODULE CONFIGURATION In order to configure the Modbus RTU module follow the steps indicated below M With the relay off install the Modbus RTU communication module into the slot located at the bottom of the equipment M Make sure it is fitted in properly M Apply power to the relay M Verify the content
5. information regarding the parameters mentioned above 4 7 10H COMMAND PRESET MULTIPLE REGISTERS It is used for the writing of multiple word type data in adjacent markers and parameters F000 to P799 019799 2800 to 899 800 to 899 MW8200 to MW8849 8200 to 8849 MF9000 to MF9174 9000 to 9174 PM3700 to 3731 3700 to 3731 Observa o M The FLOAT markers MF9000 to MF9174 use 4 bytes in the memory so they have to be written two and two For instance in order to write in the float markers 9100 to 9104 the writing of 10 words is necessary starting trom the address 9100 in the float format IEEE 754 19 Modbus RTU Commands Used qt the SRW 01 20 Configuration Command and Monitoring Via Modbus 5 CONFIGURATION COMMAND AND MONITORING VIA MODBUS In order to configure the SRW 01 its operation modes motor data etc as well as commanding it via Modbus Fieldbus and also to monitor data remotely refer to the SRW 01 manual 5 1 WLP USE IN MODBUS If there is an RS 485 interface connected to a personal computer PC the WLP software can be used for the configuration monitoring and command and also for transferring the user program in Ladder being necessary only to configure the correct used relay address in the WLP Note that considering that the WLP is normally used in Local mode the Remote Commands are referenced by the software as Commands The RS 485 can be obtained at the PC through an RS 2
6. of the parameter P084 making sure that the communication module has been properly recognized P084 1 If necessary refer to the installation guide and to the user manual Set the relay network address through the parameter P725 Valid values 0 to 247 Set the baud rate at P726 Valid values 0 4 8 kbit s 1 9 6 kbit s 2 19 2 kbit s 3 38 4 kbit s Connect the network cable wires to the XC2 connector or the DB9 Refer to the section 3 or to the user manual for more information on the parameters mentioned above 2 4 STATUS INDICATION At the SRW 01 front panel there is a bicolor LED named NET which signalizes in GREEN when the Modbus RTU communication module is correctly connected The same LED flashes in RED when the relay has acknowledged any message from the master and is responding 12 Relay Parameterization 3 RELAY PARAMETERIZATION Next only the SRW 01 smart relay parameters related to the Modbus RTU communication will be presented The detailed description of this parameter is found in the SRW 01 User Manual P202 Operation Mode Adjustable 0 Transparent Factory default 1 Range 1 Overload Relay 2 Direct Start 3 Reverse Start 5 Dahlander Start 6 Pole Changing Start 7 PLC Mode Properties Sys CFG Description This parameter allows selecting the SRW 01 operation mode The functions of digital inputs and outputs are contigured automatically according to th
7. 32 to RS 485 converter 21 Configuration Command and Monitoring Via Modbus 22 Error Related to the Serial Communication ERROR RELATED TO THE SERIAL COMMUNICATION Description It indicates that the SRW 01 has stopped receiving valid serial telegrams for a period longer than the programmed in P314 Working The parameter P314 allows the programming of a time during which the SRW 01 must receive at least one valid telegram via serial interface with address and error checking field correct otherwise it will be considered that there was any problem in the serial communication The time counting initiates after the reception of the first valid telegram After the serial communication timeout has been identified E0086 will be showed on the SRW 01 HMI and the action programmed in P313 will execute Case P313 will be configured to only fault indication P313 0 if the communication is reestablished and new valid telegrams are received the fault indication will be removed from the HMI Possible Causes Correction M Verify factors that could cause failures in the communication cables installation and grounding M Make sure that the master sends telegrams to the SRW 01 in intervals shorter than the programmed in P314 M Disable this function in P314 23
8. Motors Automation Energy Transmission amp Distribution Coatings SMART RELAY SRW 01 V4 0X Modbus RTU Communication Manual SRG EE Er E Modbus RTU Communication Manual Series SRW 01 Firmware Version V4 0X Language English Document Number 10000521657 04 Publication Date 12 2012 Summary SUMMARY ABOUT THIS MANUALL ABBREVIATIONS AND 5 2 1 1 4 4 7 NUMERICAL REPRESENTATION 2 2 1 0 02002 2224 1 21 2094 7 1 INTRODUCTION TO SERIAL COMMUNICATION 9 1 1 THE MODBUS RTU 0 2 6 9 1 2 TRANSMISSION MODES uuu L G u kaya kaska eu Ge 9 1 3 MODE MESSAGE 5 4 6 9 13 L AMO OSS u ae U 9 1 3 2 Function Cod xL Su unu reg e EIEEE EE IEE 10 susah u feed 10 ORG Depan usan saan 10 5
9. TER 6 16 P780 VALUE OF THE READING PROGRAMMABLE PARAMETER 1 16 P781 VALUE OF THE READING PROGRAMMABLE PARAMETER 2 16 P782 VALUE OF THE READING PROGRAMMABLE PARAMETER 93 16 P783 VALUE OF THE READING PROGRAMMABLE PARAMETER 4 16 P784 VALUE OF THE READING PROGRAMMABLE PARAMETER 5 16 P785 VALUE OF THE READING PROGRAMMABLE PARAMETER 6 16 4 MODBUS RTU COMMANDS USED AT THE SRW 01 17 4 1 01H COMMAND READ COIL 5 065 2 00 2 17 4 2 02H COMMAND READ INPUT STATUS 17 4 3 COMMAND READ HOLDING REGISTER 17 4 4 05H COMMAND FORCE SINGLE 7 7 2 22 2 44 4 18 4 5 06H COMMAND PRESET SINGLE REGISTER 18 Summary 4 6 OFH COMMAND FORCE MULTIPLE 58 19 4 7 COMMAND PRESET MULTIPLE REGIS
10. TERS a 19 5 CONFIGURATION COMMAND AND MONITORING VIA MODBUG 21 5 1 WEPUSE INN MODBUS ass karer 21 6 ERROR RELATED TO THE SERIAL 23 E0086 SERIAL COMMUNICATION 23 About this Manual ABOUT THIS MANUAL This manual supplies the necessary information for the operation of the SRW 01 smart relay using the Modbus RTU protocol This manual must be used together with the SRW 01 user manual ABBREVIATIONS AND DEFINITIONS ASCII American Standard Code for Information Interchange PLC Programmable Logic Controller HMI Human Machine Interface WORD 16 bit Word NUMERICAL REPRESENTATION Decimal numbers are represented by means of digits without suffix Hexadecimal numbers are represented with the letter h after the number About this Manual Introduction to Serial Communication 1 INTRODUCTION TO SERIAL COMMUNICATION In a serial interface the data bits are sent sequentially through a communication channel or bus Several technologies use the serial communication for data transfer including the RS232 and RS485 intertaces The directions that specify the RS232 and RS485 standards however do neither specify the character format nor its sequence for the data transmission and reception Therefore besides the interface it is also necessary to identify the protocol used f
11. dition is cleared and the relay status are not either TRIP or Error If the relay status is TRIP or Error it is mandatory to pertorm error reset in order to remove the fault indication 1 Stops motor It switches the motor off for the operation modes where this commands exists It is necessary to perform the error reset in order to remove the indication 2 Stops motor and resets It switches the motor off resets the commands commands It is necessary to perform the error reset in order to remove the indication 3 Goes to local It changes to local mode providing that the local remote selection is programmed to be executed via Fieldbus The indication of fault will be automatically removed if the fault condition is cleared and the relay status are not either TRIP or Error If the relay status is TRIP or Error it is mandatory to perform error reset in order to remove the fault indication For the Modbus RTU interface the following event is considered communication error E0086 Timeout in the data communication of the Modbus RTU interface has occurred The description of these errors is presented in the section 6 P314 Serial Watchdog Adjustable 0 0 Disabled Factory default 0 0 Range 0 1 to 999 0 s Enabled Properties Sys CFG Description It allows the programming of a time limit for the detection of serial interface communication error In case the SRW 01 remains without receiving
12. is selection P220 Local Remote Selection Adiustable 0 Always Local Factory default 2 Range 1 Always Remote 2 HMI key LOC HMI key REM Digital Input I3 Digital Input 14 Fieldbus LOC Fieldbus REM USB Ladder 3 4 5 7 oll il tl tl Properties Sys rw Description This parameter defines the origin of the command that will select the SRW 01 working mode Local Remote and its initial state 232 Remote Command Selection Adjustable 0 Ix Factory default 3 Range 1 HMI 2 USB Ladder 3 Fieldbus Properties Sys rw Description It defines the origin of the remote commands If P232 3 the remote commands are controlled by the industrial network master 277 Digital Output Function 278 Digital Output O2 Function 279 Digital Output Function 280 Digital Output O4 Function 13 Relay Parameterization Adjustable 0 Internal use P202 Factory default 1 Range 1 Ladder Alarm Fault NO Signal rip Error NO Signal rip Error NC Signal Properties Sys CFG Description They define the relay output control origin Internal Use it is used according to the selected operation mode P202 It indicates that the digital output has a pre defined function for that operation mode Ladder it is used by the user program implemented in Ladder Fieldbus it is used directly by the industrial network master Alarm Fault NO Signal it is used to sig
13. nal Alarm or Fault In case of Alarm or Fault the output is closed remaining like this until the cause of failure is not present anymore and the reset control is set Trip Error NO Signal it is used to signal Trip or Error In case of Trip or Error Ex No communication with the Current Measuring Unit the output is closed remaining this until the cause of the failure is not present anymore and the reset control is set Trip Error NC Signal it is used to signal Trip or Error In case of Trip or Error Ex No communication with the Current Measuring Unit the output is closed remaining like this until the cause of the failure is not present anymore and the reset control is set NOTE It is worthwhile to remember that the availability of the digital outputs 1 4 depends on the used operation mode because it is possible that one or more outputs be already pre allocated for other functions P313 Communication Error Action Adjustable 0 Only indicates fault Factory default 0 Range 1 Stops motor 2 Stops motor and resets commands 3 Goes to local Properties Sys rw Description This parameter allows selecting which action must be executed by the relay in case that a communication error is detected 14 Relay Parameterization Table 3 1 Values for the parameter P313 0 Only indicates fault Fault indication only with no action taken The indication of fault will be automatically removed if the fault con
14. or the communication Among the several existent protocols one used a lot in the industry is the Modbus RTU protocol In the sequence the characteristics of the RS485 serial interface available for the SRW 01 smart relay will be presented as well as the Modbus RTU protocol for the use of this interface 1 1 THE MODBUS RTU PROTOCOL The Modbus protocol was developed by the company Modicon part of Schneider Automation It is defined in the protocol the format of the messages used by the elements that compose the Modbus network the services or functions that can be made available via network and also how these elements exchange data in the network 1 2 TRANSMISSION MODES Two transmission modes are defined in the protocol specification ASCII and RTU The modes define the way the message bytes are transmitted It is not possible to use the two transmission modes in the same network In the RTU mode each transmitted word has 1 start bit eight data bits 2 stop bits and without parity Thus the bit sequence for one byte transmission is the following Start BO Bi B2 83 84 BS 86 BZ Stop Stop In the RTU mode each data byte is transmitted as a single word with its value in hexadecimal format The SRW 01 uses only this transmission mode for communication not having therefore the ASCII communication mode 1 3 RTU MODE MESSAGE STRUCTURE The Modbus RTU structure uses a master slave system for message exchange It all
15. ows up to 247 slaves but only one master Every communication begins with the master making a request to a slave which answers to the master what has been asked In both telegrams request and answer the used structure is the same Address Function Code Data and Checksum Only the data content has a variable size Master request message Address 1 byte Function code 1 byte Address 1 byte Function code 1 byte Data n bytes CRC 2 bytes Slave response message Data n bytes CRC 2 bytes Figure 1 1 Message structure 1 3 1 Address The master initiates the communication sending a byte with the address of the slave to which the message is destined When sending the response the slave also initiates the telegram with its own address making it possible to the master to know which slave is sending the response Introduction to Serial Communication The master can also send a message to the address 0 zero which means that the message is destined to all the slaves in the network broadcast In that case no slave will answer to the master 1 3 2 Function Code This field also contains a single byte where the master specifies the kind of service or function requested to the slave reading writing etc According to the protocol each function is used to access a specific type of data In the SRW 01 data is made available as holding registers words or coil input discrete registers bits therefore
16. rned to the CRC variable 4 The steps 2 and 3 are repeated until eight shifts have been made 5 steps 1 to 4 are repeated using the next message byte until the entire message has been processed The final content of the CRC variable is the CRC field value that is transmitted at the end of the telegram The least significant part is transmitted first CRC and next the most significant part CRC 10 Ace ssry Kit 2 ACCESSORY KIT In order to make the Modbus RTU communication possible with the SRW 01 smart relay it is necessary to use a kit for Modbus RTU communication according to the description below Information on this module installation can be obtained in the installation guide that comes with the kit 2 1 MODBUS RTU INTERFACE 2 1 1 Modbus RTU Kit Composed by the Modbus RTU communication module figure at the left and an installation guide The interface follows the EIA 485 standard The interface is electrically isolated and with differential signal which grants more robustness against electromagnetic interference The maximum distance for the connection of the devices is 1000 m Network termination via switch which must be turned on at the network extremes NA 2 1 2 Connector Pin Functions Once the Modbus RTU communication kit has been installed the relay makes available two different connectors for the interface with the network Female DB9 connector XC15 8 wire plug in terminal strip
17. ss P000 to P799 019799 P00 to 899 800 10 899 MW8200 to MW8849 8200 to 8849 MF9000 to MF9174 9000 to 9174 PM3700 to PM3731 3700 to 3731 Note The FLOAT markers MF9000 to MF91 74 use 4 bytes in the memory so they have to be written two and two For instance in order to write in the float markers 9100 to 9104 the writing of 10 words is necessary starting trom the address 9100 in the float format IEEE 754 18 Modbus RTU Commands Used at the SRW 01 4 6 OFH COMMAND FORCE MULTIPLE COILS It forces the writing of multiple bit type data i e bit markers and digital outputs Notes M In order to write in one or more of the outputs via Modbus it is necessary that at the respective parameters from P277 to P284 the option 2 Fieldbus had been selected M The system marker SX3000 performs the Trip or Error reset command M The system markers SX3001 SX3003 which are called Remote Commands are equivalent to the commands through digital inputs for the 3 wire command pushbuttons 11 12 and respectively and they are used for commanding the motor depending on the operation mode selected in P202 For instance in the operation mode Reversing Starter SX3001 turns off the motor SX3002 starts it in the direct rotation and SX3003 starts the motor in the reverse rotation M In order that the Local Remote mode be able to be selected it is necessary that P220 6 or 7 Refer to the user manual in order to get more
18. the relay does only accept functions that manipulate this type of data 1 3 3 Data Field It is a variable size field The format and contents of this field depend on the used function and on the transmitted values This field is described together with the description of the functions 1 3 4 CRC The last part of the telegram is the field for checking the transmission errors The used method is the CRC 16 Cycling Redundancy Check This field is formed by two bytes where first the least significant byte is transmitted and then the most significant CRC The CRC calculation is initiated by loading a 16 bit variable from now on referred to as CRC variable with the FFFFh value Then the steps of the following routine are executed 1 The first byte of the message only the data bits start bit parity and stop bits are not used is submitted to an XOR exclusive OR logic with the 8 low order bits of the CRC variable returning the result to the own CRC variable 2 Then the CRC variable is shifted to the right towards the least significant bit and the most significant bit position is filled with O zero 3 After this shift the flag bit the bit that was shifted out of the CRC variable is analyzed with the following outcomes It the bit value is zero nothing is done If the bit value is 1 the content of the CRC variable is submitted to an logic with a constant value of A001h and the result is retu
19. us RTU Commands Used qt the SRW 01 Note M The FLOAT markers MF9000 to MF9174 use 4 bytes in the memory so they have to be read two and two For instance in order to read the float markers 9100 to 9104 the reading of 10 words is necessary starting from the address 9100 The reading will be in the float format IEEE 754 4 4 05H COMMAND FORCE SINGLE COIL It forces the status of a bit marker or a digital output individually Notes M In order to write in one or more of the outputs via Modbus it is necessary that at the respective parameters from P277 to P284 the option 2 Fieldbus had been selected M The system marker SX3000 performs the Trip or Error reset command The system markers SX3001 SX3003 which are called Remote Commands are equivalent to the commands through digital inputs for the 3 wire command pushbuttons 11 12 and respectively and they are used for commanding the motor depending on the operation mode selected in P202 For instance in the operation mode Reversing Starter SX3001 turns off the motor SX3002 starts it in the direct rotation and SX3003 starts the motor in the reverse rotation M In order that the Local Remote mode be able to be selected it is necessary that P220 6 or 7 Refer to the user manual in order to get more information regarding the parameters mentioned above 4 5 06H COMMAND PRESET SINGLE REGISTER It writes one word type datum i e a marker or a parameter Addre
20. us over serial line V1_02 pdt Modbus Application Protocol VI 1 01h Command Read Coil Status 02h Command Read Input Status 03h Command Read Holding Register 05 Command Force Single Coil 06h Command Preset Single Register OFh Command Force Multiple Coils 10h Command Preset Multiple Registers I El ES S El In order to get information on the implementation of the mentioned commands refer to the indicated specifications 4 1 01H COMMAND READ COIL STATUS Use this function to read bit markers and digital outputs Multiple coils can be read simultaneously provided that their addresses are adjacent for instance MX6100 to MX6110 The system markers SX3001 to SX3006 do not allow multiple reading i e each marker must be read individually The Remote Commands are used to start stop change the speed etc of the motor when a specific operation mode is selected in P202 Local Remote indicates the source of the SRW 01 commands when SX3006 1 the SRW 01 is in remote mode 4 2 02H COMMAND READ INPUT STATUS It is used specitically for reading the digital inputs Digital Inputs Control Unit IX1 to IX4 11 to 14 2201 to 2204 Digital Inputs Expansion Unit IX5 to IX10 15 to 110 2205 to 2210 4 3 03H COMMAND READ HOLDING REGISTER It is used for the reading of multiple parameters or word markers MF9000 to MF9174 9000 to 9174 PM3700 to PM3731 3700 to 3731 SW3300 3300 17 Modb
21. valid telegrams longer than the time programmed in this parameter it will be considered that a communication error happened the message E0086 be showed on the HMI and the option programmed in P313 will be executed After being powered up the SRW 01 starts counting this time from the first received valid telegram The value 0 0 disables this function P725 Communication Module Address Adjustable 0 255 Factory default 63 Range Properties Sys CFG Description It allows programming the address relay communication board It is necessary that each device in the network has an address different from the others The valid addresses for this parameter depend on the used protocol Modbus valid addresses 1 to 247 DeviceNet valid addresses 0 to 63 Profibus gt valid addresses 1 to 125 If this parameter is changed it is not necessary to turn off and on again the relay to make the address valid only for Modbus RTU network 15 Relay Parameterization 726 DeviceNet Modbus Board Baud Rate Adjustable 0 125 Kbit s 4 8 Kbit s Factory default 3 range 1 250 Kbit s 9 6 Kbit s 2 500 Kbit s 19 2 Kbit s 3 Autobaud 38 4 Kbit s Properties Sys CFG Description It allows programming the desired baud rate for the DeviceNet and Modbus boards in bits per second This rate must be the same for all the devices connected to the network The values at the right above refer exclusively to the Modbus RTU network
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