User Manual
Contents
1. In0 All further signals will obtain the accordingly consecutive numbers For example if BASIS_ADDR has the value 100 then the first digital signal at input input nO will get the logical signal number 100 and the last digital signal at input n37 will get the logical signal number 131 This signal number will be transferred to the S7A driver and will be used by the clients of the S7A driver as a reference to the digital signal The supported value range of this parameter is 1 to 4065 A value outside of this range would cause an abort of the function block with an error code W 16 A225 sector error within the 34 parameter at the RTC output parameter of the FB Note If multiple instances of the FB2 are declared within the FB3 S7A_SCAN_CONTAINER each instance of FB2 has to have its individual and unique BASIS_ADDR value Input GENERAL_POLL By the GENERAL_POLL input the function block will get signalised that an interrogation command was requested The FB writes the current signal state and timestamp of all 32 signals into the FIFO buffer References This FB will be called from FB3 S7A_SCAN_CONTAINER FB3 S7A_SCAN_CONTAINER The FB serves as a collector container for all instances of the real Scan FBs FB2 S7A_SCAN_32D_SIGNALS This FB contains one or more instances of FB2 depending on how much digital signals has to be monitored The user has to declare this instances of FB2 as STAT variables in the interface of FB3 See the followi2. configuration tree view and click the Statistics button in the Run time toolbar The following figure shows the System Statistics page of a S7A dongle for version 7 40 with the Digital Signal DS option available E Proficy FIXIDEFAULT S7A Configurator File Edit view Display Mode Options Help elr a u e a o 7 System Statistics Blocks Requested Successful Timeouts Retries Errors Dweruns y y Configuration Number of Channels 3 Number of Devices is Number of Blocks 54 j Write Queue Pool load Performance Bytes Sec Misc un Request Pool Write Queue Total Write Req Licence Options For Help press Fi Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 13 5 1 S7A driver configuration The S7A driver was extended by the Memory Area Digital Signals DS At least one DS master block has to be defined in the S7A power tool In addition to the DS master block one or multiple so called DS slave blocks can be added A DS Masterblock always has a Primary Rate equal or greater than zero wheras a DS slave block has to have the Primary Rate DISABLED For both block types master and slave the checkbox Enable must be checked The fragmentation in master and slave blocks is necessary because a si
3. in the PLC at the time as the signal state change occurs and to transfer this time stamp together with the related signal state to the SCADA system Furthermore the signals and their time stamp will be buffered within a FIFO buffer of the PLC and asynchronously transferred to the S7A driver This buffering ensures that no signal changes will be lost assumed that the size of the FIFO buffer is sufficient in case of short signal changes and or low communication speed between PLC and S7A driver The signal transfer to the S7A driver occurs by a dynamically length transfer data block The S7A driver periodically polls a single handshake byte of this data block The handshake byte will be set by the PLC when new signal changes occurred and buffered in the FIFO Afterwards the S7A driver just reads the amount of data bytes which are needed to transfer these signal changes including their timestamps Due to this transfer method the communication traffic between PLC and S7A driver is reduced to a minimum and even a large number of signals can be transferred effectively by a quiet short transfer data block The following picture shows an overview about this new functionality of the driver da l up to 4096 digital signals a Scanner for buffering the signals with their timestamps asynchronous transfer of signals with their timestamps from the PLC to the S7A driver Transfer Buffer PL
4. scan cycle monitoring time which in turn sets the PLC CPU in STOP mode The reason for the increase of the scan cycle time is that on an interrogation request all signals will be scanned and thus signal change messages for all signals have to be transferred to the FIFO and furthermore transferred to the S7A transfer buffer On hundreds or thousand of signals this operation will generate an significant CPU load and thus a long scan cycle time In comparison to the regular program flow this additional scan cycle time can be many times over the regular program scan cycle time With the Dispatcher the scan cycle load for an interrogation request would be spreaded over multiple program cycles Functionality of the Dispatcher If the input GERNERAL_POLL receives an interrogation request the first step network 1 for the FB3 is to load the variable DISPATCH_COUNTER by a preset value Example Assumed that FB3 contains 4 instances of the Scan FB2 By setting the DISPATCH_COUNTER to the value 4 it is possible to splitt the interrogation request to 4 scan cycles In a single scan cycle just one instance of FB2 will be called with the interrogation request The trick is that the GENERAL_POLL input of a specific Scan FB2 instance will be set to TRUE on a specific Dispatch Counter value Example The GENERAL_POLL input of the first instance signal 1 to 31 of FB2 will set to TRUE if the Dispatch Counter has the value 4 The GENERAL_POLL input of the
5. second instance signal 32 to 64 of FB2 will set to TRUE if the Dispatch Counter has the value 3 The GENERAL_POLL input of the fourth instance signal 97 to 128 of FB2 will set to TRUE if the Dispatch Counter has the value 1 The Dispatch Counter will be decremented at the end of each scan cycle It is not mandatory that each Scan FB2 instance has its own Dispatch Counter value It is also allowed that multiple Scan FB2 instances shares the same value of the Dispatch Counter Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 11 4 1 4 1 1 4 1 2 4 2 The decision whether the interrogation command should be divided on multiple PLC scan cycles depends on the amount of Scan FB2 instances and on the performance of the PLC CPU and should decided empirically References This FB will be called from FB1 S7A_TRANSFER Data components The specified PLC program componentes will require 4 data components Each two of global data blocks and instance data blocks Global data blocks FIFO buffer for the signal signal messages The minimum size of the FIFO buffer DB is determined by the number of all digital signals which are defined in the particular application A a general rule the FIFO buffer DB should be large enough to host one data element per digital signal A data element of a signal signal has a length of 10 bytes Refer
6. slave block a E DYNAMICS S74_DigitalSignals S74 Configurator File Edit View Display Mode Options Help Saa Ol oll gt a fm ul E ool Block Name Ds1_1000 Enable 7 Description DS1001 2d 140 Address Setup fp Polling Setup D52001_320 DS4001 4d Memory Area Digital Signals DS y Primary Rate 01 Secondary Rate Disabled Starting Address LL A Phase 00 Ending Address SS Access Time Disabled No of Elements Data Type BIT y m Misc Setup l Deadband 1 Transfer DB jim Debug Options Block Write Mode Disabled X Dues Log Reads 1 Latch Data J Disable Outputs Log Writes I Disable COMM Alarms I gt ea x For Help press Fi num ZA figure 4 DS master block Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 14 5 2 5 2 1 5 2 2 i E DYNAMICS S7A_DigitalSignals 57A Configurator File Edit View Display Mode Options Help Block Name ost 001_2000 Enable JV Description 7140 Address Setup _ Polling Setup Memory rea Digital Signals DS Primary Rate C Disabled 2 Secondary Rate Disabled Starting Address fi 001 Ending Address fac aes Access Time 05 00 No of Elernents f1ooo Data Type BIT y m Misc Setup Deadband 1 Transfer DB B
7. C SCADA System a periodically polls the PLC s transfer buffer for new data signals S7A Driver OPC Server NIO Interface S7A Client 1 S7A Client 2 iFix OPC client e g iHistorian figure 1 overview components Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 3 1 1 Calling and datablock structure The diagram below shows the calling structure of functions FC and the function blocks FB and their associated data blocks global and instance DBs FC1 FIFO_INIT DB10 FIFO_DB re Data Entries OB1 Main Application Programm FC3 FC2 FIFO_GET FIFO_PUT FB1 FB3 FB2 S7A_TRANSFER S7A_SCAN_ S7A_SCAN_ CONTAINER 32D_SIGNALS 1 Instance of FB2 FB2 n Instance of FB2 Instance DB1 Instance DB3 raa Data Area DB100 cla S7A_TRANSFER DB Area PLC SCADA System Hand shake figure 2 calling and data block structure Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol DS Datablock S7A_DRIVER Legend e e gt data direction function call FB function call FC digital input signa
8. Generalabfrage auf mehrere Zyklen verteilt werden U GENERAL_POLL f Steht nur f r einen Zyklus an SPEN GPEX ff wenn Generalsbfrage dann mu der Dispatch L 5 T ND NTEDATCH PAMITRD figure 3 static data declaration in FB3 Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 10 3 1 3 1 Later on when the Instance DB of the FB3 is created this Instanz DB contains in additition to its own instance data the instance data of all the FB2 instances which are declared in the FB2 s static interface This multi instance DB saves storage capacity reduces the number of required DBs and thus minimize the use of the PLC resources Input Symbolic name Type specification FIFIO_DB_NO bool Number of the DB which serves as FIFO buffer Output RTC Int Function return value 0 exit the function without error lt gt 0 error occurs within the function General Poll Interrogation request Dispatcher A special function of the Scan Container FB is the General Poll Dispatcher This function serves as a program load splitter of an interrogation request for all signals because it splits this command to multiple PLC cycles The splitting is necessary when a large number of signal scanFBs FB2 are declared in FB3 Otherwise an interrogation request could cause a scan cycles time out current scan cycle time exceeds the
9. J rgen Statler User Manual Intersystem transmission of digital signals with timestamp between Siemens S7 PLC Systems and S7A Driver OPC Server Date 31 03 2011 Author J Stahler InCoSol Industrial Communications Solutions Table of contents 1 Introduction 243222 32 2 er Bo ee IE one ak ew A er oe Be els 3 1 1 Calling and datablock structure 2 cc ee 4 2 Module structurec ce attests eae lok bale en Slate ne a Radial ee ate a 5 2 1 FIFO Managements aaa te td lula parade a Bal Mea ded a Eee ead 5 2 14 FC1 FIFQZINIT 0 8 2 eee tet aaa a na ea 5 2 1 2 FOC2 FIFOLPUT 0005 sete ea Sie er na Fan een a ee 6 2123 PCS RIFOY GED 244 Sb ak atta a feb ante ond etek lied dt oad deed ee rar 6 2 1 4 thC4 FIFOZCOUNT Wo onc a Bouts Reale ee td re i 7 3 Signal Scanner and transfer to the S7A driver 0 eee 8 3 1 Funetion DIOCK Ss 20 5 Soe eee A tag erates A a ene ee 8 31 EBI S7A TRANSFER ap nimiin 8 signi ate eel ea BER aes ae Da ae eee ee 8 3 1 2 FB2 S7A_SCAN_32D_SIGNALS 00 00 02 eee 9 3 1 3 FB3 S7A_SCAN_CONTAINER 0 00000 e eee eee 10 4 Data components ono Pe Sh be eee eae he ba SAS EA A eee eae eee 12 4 1 Globalidata blocks enmedio see Ah thee o Sug edi er ee ead et a 12 4 1 1 FIFO buffer for the signal state messages 000 cece eee 12 4 1 2 Transfer buffer for the S7A communication 0 000 ee eee 12 4 2 Instance data DIOCKS ici E er E
10. Sia en Ma el Sia alia goa at wena ele 12 5 S7A Con fig ratio Ni sssi ee Ba ee ee re pe Een 13 5 1 S7A driver configurations sesira narsa gia aaa eee 13 5 2 Clientconfig ratio Mie sorene nre boty a e deed 14 5 21 Address SYNTAX ii arate a alleen ea 14 5 2 2 interrogation commandi 200 He eE Re A Ra na ae 14 Table of figures figure 1 overview components 0 60 cee ne 3 figure 2 calling and data block structure o ooooooorrrorrr een 4 figure 3 static data declaration in FB3 0 0 ee 10 figure 4 DS master blocks iio aig pages a Fon ak Bare aie we ek ee SE kee oe ee 13 figure 5 DS Slave blo k icc esc eee er nee he a er eee Te per ba ee 14 Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 2 1 Introduction The S7A Version 7 40 with build no 105 offers a new function which allows you to receive a number of up to 4096 digital signals with timestamp from the PLC and to forward these signals to the clients FIX and or OPC By the regular polling of the PLC data area the timestamp will be generated by the SCADA System within the S7A driver Due to communication delays between the PLC and the driver such a timestamp do not represent the real time the time the signal actually occured of the signal With the new S7A option Digital Signals it is now possible to generate the timestamp
11. ally error message For general error codes see decsription of SFC24 TEST_DB References This FC will be called from FB1 S7A_TRANSFER 2 1 4 FC4 FIFO_COUNT Returns the current number of data elements within the FIFO which is specified by the parameter FIFO_DB_NO Inputs Symbolic name Type Specification FIFO_DB_NO Int Number of the DB which serves as FIFO buffer Outputs COUNT Int Number of data elements currently in the FIFO RET_VAL Int Return value 0 exit the function without error lt gt 0 error occurs within the function Note Before this function will be called it is mandatory to initialise the FIFO DB by calling the function FIFO_INIT FC1 First of all the function checks if the data block which is passed to the function by the parameter FIFO_DB_NO already exists In case the DB is not existing the function will be canceled with an appropriate error code at output RET_VAL In case it exists the actual amount of data elements will be read from the FIFO header and returned on the output parameter COUNT In case of an invalid FIFO DB number the output RET_VAL will return a generally error message For general error codes see decsription of SFC24 TEST_DB References This FC will be called from FB1 S7A_TRANSFER Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 7 3 1 3 1 1 Signal Sca
12. curs within the function Note Before this function will be called it is mandatory to initialise the FIFO DB by calling the function FIFO_INIT FC1 First of all the function checks if the data block which is passed to the function by the parameter FIFO_DB_NO already exists In case the DB is not existing the function will be canceled with an appropriate error code at output RET_VAL In case the DB already exists the function will check if there is sufficient space for the new data element inside the FIFO DB If so the data element will be copied into the FIFO There will be no implied check whether the length of the FIFO data element as defined in FIFO_INIT and the specified length of the source data element denoted inside the ANY Pointer of parameter FIFO_DATA are equal In case of inconsistency in length the internal call to the BLKMOV function will fail and the function will be aborted with an appropriate error code at output RET_VAL In case that the FIFO buffer is full the output RET_VAL will return the specific error code W 16 8081 For general error codes see decsription of SFC24 TEST_DB References This FC will be called from FB2 S7A_SCAN_32D_SIGNALS FC3 FIFO_GET Reads the first data element from the FIFO DB provided that the FIFO is not empty Inputs Symbolic name Specification FIFO_DB_NO Number of the DB which serves as FIFO buffer FIFO_DATA ANY Pointer to the buffer for a data element which is remove
13. d from the FIFO Outputs RET_VAL Int Function return value 0 exit the function without error lt gt 0 error occurs within the function Note Before this function will be called it is mandatory to initialise the FIFO DB by calling the function FIFO_INIT FC1 First of all the function checks if the data block which is passed to the function by the parameter Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 6 FIFO_DB_NO already exists In case the DB is not existing the function will be canceled with an appropriate error code at output RET_VAL In case the DB exists the function will check if the FIFO contains at least one data element If so the element which first came in will be copied to the target data element which is addressed by the ANY Pointer of the input parameter FIFO_DATA There will be no implied check whether the length of the FIFO data element as defined in the FIFO_INIT and the target data element as defined in the ANY Pointer are equal In case of inconsistency in length the internal call of the BLKMOV function will fail and the function will be aborted with an appropriate error code at output RET_VAL In case that the FIFO is empty the output RET_VAL will return the specific error message W 16 8082 In case of errors due to an invalid source data element invalid ANY Pointer it will return a gener
14. e function without error lt gt 0 error occurs within the function Inputs n0 In32 The digital signal inputs n0 to In31 can be connected with any digital operand E A M or DBX Every time the signal changes rising or trailing edge the FB generates a data element signal state and timestamp and put it into the FIFO buffer Furthermore the last signal state and the corresponding timestamp will be saved into an internal array part of the instance data area within the instance DB The information of the last signal state and its timestamp will be needed when an interrogation command is requested In case that an interrogation command was request before the FB the first time has detected a signal change e g after a restart of the PLC program and before the signal state has changed from FALSE to TRUE so the signal state is still FALSE a message with the initial signal state FALSE and the current timestamp will be generated and transferred into the FIFO buffer In the Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 9 3 1 3 strict sense that s not the real timestamp of the signal but the timestamp represents the time as the interogation command was issued Input BASIS_ADDR The numeric value which is passed to the function by the input BASIS_ADDR determines the logically signal number of the first digital signal
15. en the control tag s current value will be set to any value Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 15
16. ence UDT2 definition Furthermore the FIFO header requires 10 bytes Example on how to calculate the minimum size 5 instances of the Scan FB2 are defined within the Scan Container FB3 The FIFO buffer DB should have a minimum size of 10 5 x 32 x 10 1610 byte 10 bytes FIFO header 5 instances of FB2 each has 32 signals each signal requires 10 bytes This size ensures that on an interrogation command the data elements of all signals can be hosted by the FIFO buffer Even though not all signals will be scanned in a single scan cycle since the General Poll Dispatcher splitts it to multiple scan cycles the FIFO buffer should have this minimum size It can t be assumed that the signal messages will be transfered to the S7A driver immediately after the signal state change was detected If the S7A driver is offline or in case that a large number of signal state changes occures at the same time interrogation request the FIFO buffer DB has to temporarily store the data element for all these signal messages If the PLC provides enough memory we suggest to configure the FIFO buffer DB twice the minimum size Transfer buffer for the S7A communication The signal messages in the FIFO will be forwarded to the S7A driver by the so called Transfer DB The Transfer buffer do not have a fixed structure but it will be filled dynamically by the PLC program FB1 Dependig on the number of signal messages in the FIFO buffer DB the Transfer DB wi
17. f the FIFO data block which is passed to the function by parameter FIFO_DB_NO already exists In case the DB is not existing the function will be canceled with an appropriate error code at output RET_VAL If the data block exists the function calculates based on the size of the data block and the size of the FIFO data element passed to the function by parameter FIFO_ENTRY_SIZE the maximum number of data elements which can be stored inside the FIFO The calculated number of data elements will be returned at the output NO_OF_ELEMENTS Note The data bytes of the FIFO DB will not be initialised set to 0 Only the header data byte 0 9 of the FIFO DB will be initialized with the initial values for first last and number of elements in FIFO In case that no errors were identified the output RET_VAL returns the value 0 Otherwise it returns a general error code For general error codes see description of SFC24 TEST_DB References This FC will be called from FB1 S7A_TRANSFER Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 5 2 1 2 2 1 3 FC2 FIFO_PUT Writes a data element into the FIFO DB Inputs Symbolic name Type Specification FIFO_DB_NO Int Number of the DB which serve as FIFO buffer inserted into the FIFO DB Outputs RET_VAL Int Function return value 0 exit the function without error lt gt 0 error oc
18. ll be filled with these messages The S7A driver do not poll the whole size of the Transfer DB but only the number of bytes which are currenly be used filled by the PLC program The reserved configured size for the Transfer DB depends on the expected amount of simultanous signal state changes As a basic rule you can estimate 25 of the size of the FIFO Buffer DB The maximum size of the Transfer DB is 10 000 bytes Instance data blocks The function blocks FB1 S7A_TRANSFER and FB3 S7A_SCAN_CONTAINER are requiring Instance DBs The instance DB of FB1 S7A_TRANSFER has a pre defined fixed size The size of the instance DB for FB3 S7A_SCAN_CONTAINER is dynamically and depends on the amount of instances of FB2 inside FB3 Each FB2 instance allocates 346 bytes within the instance DB of FB3 Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 12 S7A Configuration Note From the license point of view this new function is an option means it is not available with a standard license A standard license has to be extened possible by a remote dongle update to make the DS option available The actual license version and available options of a particular dongle can be checked on the System Statistics page in the S7A power tool To reach this System Statistics page open the S7A Power tool select the S7A root entry in the driver
19. lock Write Mode Disabled y ih Debug Options Data Monitor Log Reads T Latch Data Disable Outputs I Log Writes T Disable COMM Alarms I gt O x For Help press Fi am F figure 5 DS Slave block Client configuration Digital signals can be processed eighter by the iFIX e g by using the DA Block or by an OPC Client In FIX Digital Alarm Tags can be used for DS digital signals The Alarm Summery windows shows the date and time of the PLC timestamp Address syntax The address syntax of iFIX Tag I O Addresses and OPC Item IDs for digital signals is the same lt Device Name gt DS lt Signal Number gt Example D11 DS 1000 for the digital signal 1000 Interrogation request The driver initiates automatically an interrogation request on each system start Means after each start of the S7A driver or FIX all digital signals will be requested and the PLC sends the current state and timestamp of all signals By using a special control tag it is possible to initiate an interrogation request directed from the client application The iFIX Tag I O Address or rather the OPC Item ID of the control tag has the following syntax IPOLL lt Block Name gt whereas Block Name is the name of the DS Masterblock Referring to the figure 3 above image DS Master block the control tag has the following format POLL DS1_ 1000 The interrogation command will be send wh
20. ls any type of digital operand Page 4 2 Module structure The necessary PLC program modules for capturing buffering and the transmission of the digital signals are divided into two groups 1 Four function FCs used for the management of the FIFO buffer 2 Three function blocks FBs are required for the scanning of digital signals and for the transfer of signal change messages to the S7A driver The functions FCs and function blocks FBs may not be changed by the user except to the function block named S7A_SCAN_CONTAINER FB3 2 1 FIFO Management For the FIFO management within the PLC the four function FC1 FIFO_INIT FC2 FIFO_PUT FC3 FIFO_GET and FC4 FIFO_COUNT are implemented These functions can handle any size and structure of data The contents of the data element is transparently for the FIFO functions Certainly only data elements of the same length can be managed within the FIFO For this particular application a FIFO data element entry has a size of 10 byte 2 1 1 FC1 FIFO_INIT Inputs Symbolic name Type Specification FIFO_DB_NO Int Number of the DB which serve as FIFO buffer FIFO_ENTRY_SIZE Int Length of one FIFO data element in bytes Outputs NO_OF_ELEMENTS Word Number of data elements which can be stored within the FIFO DB RET_VAL Int Function return value 0 function returned without error lt gt 0 error occurs within the function First of all the function checks i
21. ls from or to the S7A driver would be restored to initial values Afterwards the handshake signals are in a defined initial state Cyclic function In case that the input N T is set to FALSE the main functions of the FB1 will be executed These are 1 Check if an interrogation command from the S7A driver was sent If so the interrogation command will be forwarded to the FB3 S7A_SCAN_CONTAINER 2 FB3 S7A_SCAN_CONTAINER will be called Within the FB3 all instances of FB2 S7A_SCAN_32D_SIGNALS will be invoked 3 Checks if the FIFO DB contains data elements digital signals If so these signals will be removed from the FIFO and written to the Transfer DB In case that the Transfer DB is not available locked by the S7A driver or the capacity of the Transfer DB is reached the data elements signals remain in the FIFO and the function block ends 3 1 2 FB2 S7A_SCAN 32D SIGNALS This FB monitores changes of up to 32 digital signals If the FB has recognised a signal state change it creates a data element and writes this data element into the FIFO buffer Inputs Symbolic name Specification 1 digital signal input 2 digital signal input In31 bool 32 digital signal input FIFO_DB_NO Int Number of the DB which serves as FIFO buffer BASIS_ADDR Int Signal number of the first digital signal GENERAL_POLL bool TRUE if the interrogation command was requested Output RTC Int Function return value 0 exit th
22. nction block which must be called periodically within OB1 Note This FB may not be changed by the users Inputs Symbolic name Specification TRUE to initialise the function FIFO_DB BlockDB DB which serves as FIFO buffer FIFO_ELEM_SIZE length of the FIFO data element in byte TRANSFER_DB BlockDB DB which serves as transfer buffer to the S7A driver Outputs RTC Int Number of data elements inside the FIFO RET_VAL Int Function return value 0 exit the function without error lt gt 0 error occurs within the function The FB1 controls the transfer to the S7A driver via the transfer DB and furthermore it calls the FB3 S7A_SCAN_CONTAINER which in turn calls all the instances of FB2 S7A_SCAN_32D_SIGNALS For the initialisation of the whole application the input N T has to be set to TRUE for at least one PLC program cycle During the initialisation a parameter check will be done first It checks if the FIFO DB passed to the function block by parameter FIFO_DB exists In case that the DB exists the function FC1 FIFO_INIT will be called to initialize the FIFO The next step is to check if the Intersystem transmission of digital signals with timestamp between Siemens S7 PLC systems and S7A Driver OPC Server Date 31 03 2011 copyright InCoSol Page 8 S7A Transfer DB passed to the function block by parameter TRANSFER_DB exists In case it exists it will get filled with null values Thereby possible pending handshake signa
23. ng screen shot for an example on how and where to declare the FB2 instances within the interface of FB3 HSLAD STL FBD FB3 S7A_SCAN CONTAINER ET2005_CPU ET200S_CPU IM151 8 PN DP CPU FB3 a File Edit Insert PLC Debug View Options Window Help Oe SOS se elle Be oe lt gt ah Ot ne dl Contents Of Environment Interface STAT BS New network GP_DISPATCH CP_DISPATCH_COUNTER Word 6 0 H E FB blocks H E0001600032 E0001t00032 7A_SCAN_32D_SIGNALS 8 0 H E FC blocks E0033t 00064 E0033t 00064 S7A SCAN 32D_SIGNALS 356 0 E SFB blocks El025to1056 dd ElO25to1056 S7A_SCAN_32D_SIGNALS 704 0 H E SFC blocks E4065t04096 Ch Es065to4096 S7A SCAN 32D_SIGNALS 1052 0 H M Multiple instances E0065t 00096 ES EO065t 00096 S7A_SCAN_32D_SIGNALS 1400 0 H Libraries E0097t 00128 E lnstances of FB2 74_ScAN_32D_SIGNALS 1748 0 EO129t 00160 GF Eusereuviou S7A_SCAN_32D_SIGNALS 2096 0 EO161t00192 EO161to019Z S7A SCAN 32D_SIGNALS 2444 0 EO193t 00224 EO193t 00224 7A_SCAN_32D_SIGNALS 2792 0 B0225t00256 ji E0225t00256 S7A_SCAN_32D_SIGNALS 3140 0 ae ann E0257t 00288 7A_SCAN_32D_SIGNALS 3488 0 A norma onen ema onam aon remar anar a FB3 Title Container f r alle Instanzen von S7A_SCAN_3ZD_SIGNALS Network 18 Generalabfrage auf mehrere Zyklen verteilen Um die Zykluszeit bei einer Generalabfrage nicht zu sehr in die H he zu treiben kann die
24. ngle DS block master or slave just can contain a maximum of 1024 digital signals To receive the full range of 4096 digital signals a minimum of four DS blocks one master block and three slave blocks is necessary The actual number and the size of the blocks are arbitrary and can be determined according to the application requirements Only the Master block communicates to the PLC The Master block reads all digital signal messages from the PLC s data block which is defined in the field Transfer DB and passes these messages to its own block or to the corresponding slave blocks If a digital signal message will be received which can t be found in a Master or a Slave block the message will be discarded The field Starting Address defines the logical number of the first digital signal within the block The field No of Elements defines the number of digital signals the block contains The field Ending Address shows the logical number of the last digital signal within the block The signal ranges of the Master and Slave blocks may not overlap The field Transfer DB defines the PLC s data block number on which the driver receives the digital signal messages The Transfer DB number must be correspond to the number of the so called S7A Transfer DB on the PLC site see also 4 1 2 The Transfer DB number has to be defined for master block as well as for all slave blocks The following figures show the data block configuration of a DS master and
25. nner and transfer to the S7A driver The function blocks FB1 S7A_TRANSFER FB2 S7A_SCAN_32D_SIGNALS and FB3 S7A_SCAN_CONTAINER are serving for the scanning of digital signals and for the transfer of these signals to the S7A driver Main FB is the FB1 S7A_TRANSFER which in turn calls the FB3 S7A_SCAN_CONTAINER The FB3 contains one or more instances of FB2 S7A_SCAN_32D_SIGNALS Each instance of FB2 can handle up to 32 digital signals Example To monitor 100 digital signals it is necessary to declare 4 4 x 32 128 instances of FB2 within FB3 Both FBs FB2 and FB3 have declared static data so they require an instance DB Since instances of FB2 are declared as static data within FB3 just one instance DB for FB3 is required This instance DB contains the static data of the single FB3 instance and furthermore the static data of all FB2 instances which are declared within the FB3 Therefore this DB is a so called multi instance DB This multi instance DB was established to reduce the amount of necessary instance DBs to a minimum Together with the instance DB for the FB1 S7A_TRANSFER only two instance DBs are required for this particular application Furthermore a global DB for the FIFO buffer and another global DB as transfer buffer to the S7A driver are required Function blocks The following section describes all function blocks which are the main part of the entire PLC software FB1 S7A_TRANSFER It is the main fu
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