Buffering of process messages including time stamps with ALARM_7B

Transcription

1 Application Example 02/2015 Buffering of process messages including time stamps with ALARM_7B SIMATIC PCS 7 V8.1, V8.0, V7.1

2 Warranty and liability Warranty and liability Note The Application Examples are not binding and do not claim to be complete regarding the circuits shown, equipping and any eventuality. The Application Examples do not represent customer-specific solutions. They are only intended to provide support for typical applications. You are responsible for ensuring that the described products are used correctly. These application examples do not relieve you of the responsibility to use safe practices in application, installation, operation and maintenance. When using these Application Examples, you recognize that we cannot be made liable for any damage/claims beyond the liability clause described. We reserve the right to make changes to these Application Examples at any time without prior notice. If there are any deviations between the recommendations provided in these application examples and other Siemens publications e.g. Catalogs the contents of the other documents have priority. Siemens AG 2015 All rights reserved We do not accept any liability for the information contained in this document. Any claims against us based on whatever legal reason resulting from the use of the examples, information, programs, engineering and performance data etc., described in this Application Example shall be excluded. Such an exclusion shall not apply in the case of mandatory liability, e.g. under the German Product Liability Act ( Produkthaftungsgesetz ), in case of intent, gross negligence, or injury of life, body or health, guarantee for the quality of a product, fraudulent concealment of a deficiency or breach of a condition which goes to the root of the contract ( wesentliche Vertragspflichten ). The damages for a breach of a substantial contractual obligation are, however, limited to the foreseeable damage, typical for the type of contract, except in the event of intent or gross negligence or injury to life, body or health. The above provisions do not imply a change of the burden of proof to your detriment. Any form of duplication or distribution of these Application Examples or excerpts hereof is prohibited without the expressed consent of the Siemens AG. Security information Siemens provides products and solutions with industrial security functions that support the secure operation of plants, solutions, machines, equipment and/or networks. They are important components of a holistic industrial security concept. With this in mind, Siemens products and solutions undergo continuous development. Siemens recommends strongly that you regularly check for product updates. For the secure operation of Siemens products and solutions, it is necessary to take suitable preventive action (e.g. cell protection concept) and integrate each component into a holistic, state-of-the-art industrial security concept. Third-party products that may be in use should also be considered. For more information about industrial security, visit To stay informed about product updates as they occur, sign up for a productspecific newsletter. For more information, visit Entry ID: , V3.1, 02/2015 2

3 Table of contents Table of contents Warranty and liability Task Solution Overview of complete solution Description of the core functionality Hardware and software components used Applicability Function mechanisms Function and organization of the message buffer Function of the connection monitor Description of the block Function Block I/Os Message behavior Startup behavior Using the block Generating the block with the SCL source Using the block from the library CFC configuration Script for connection monitoring Demo Project Start-up Description of the user interface Literature Related documents Internet links History Entry ID: , V3.1, 02/2015 3

4 1 Task 1 Task Description of the automation task With the conventional alarm blocks, "Alarm_8" and "Alarm_8P", changes in the status of events/alarms, together with a time stamp, can be reported to the operator system. The time stamp is generated at the same time as the alarm block is called. For the purpose of traceability, the process messages in the automation system shall remain available, even during a disruption to the connection to the operator system. Furthermore, the time stamp indicating when the event occurred shall be stored and displayed when the event is displayed on the operator system at a later time. Fig. 1 1 In specific projects there is a requirement to send alarms and messages originating in subordinate systems, together with their time stamps, to the operator system via a central S7-400 controller. Applications with the following configurations are conceivable: In hierarchical control topologies with S7-300 controllers For time stamping signals in an ET 200 In telecontrol applications Entry ID: , V3.1, 02/2015 4

5 2 Solution 2 Solution 2.1 Overview of complete solution Overview With the solution described here, the connection between the automation system (AS) and the operator system (OS) is continuously monitored. If the connection to the OS is interrupted the alarm signals for the events, including their time stamps, will be stored. These time stamps can be generated by the CPUbased clock or by an external source. With an existing or restored connection, the buffered alarms, together with the time stamp that was generated when the event occurred, will be sent to the OS. Fig. 2 1 Alarm Buffer cyclic connection check create alarm messages System Archive This solution consists of the "ALARM_7B" alarm block, documentation describing its mode of operation and instructions with an example of how the block is used. Entry ID: , V3.1, 02/2015 5

6 2 Solution General The application software can roughly be divided into two parts. 1. Automation part Logging of the alarms Buffering of the alarms with original time stamp Transmission of the alarms with original time stamp to WinCC 2. OS section Transfer of the connection acknowledgment to the ALARM_7B blocks in the AS program Display and archiving of the messages Automation part The automation part consists of the "ALARM_7B" block. Each activated instance of this block requires its own data block. This data block includes the memory for buffering the alarms. The alarms are transferred to the OS by means of the "ALARM_8P" system function. OS section The OS part executes a cyclic operation which sets the tags for connection monitoring. To this end, the program code for setting the tags for connection monitoring of all "ALARM_7B" blocks must be edited manually. The display and archiving of messages in the OS is carried out with the aid of the standard messaging system. Entry ID: , V3.1, 02/2015 6

7 2 Solution 2.2 Description of the core functionality The "ALARM_7B" function block is used to generate messages in the AS and to transmit them to the higher-level OS. If the connection to the OS is interrupted, a configurable number of signal changes, including the associated values and time stamps, will be stored in the buffer. After the connection is restored, a message for each signal change, together with its original time stamp, is sent to the OS. The "ALARM_8P" system function block is used to send these messages. The size of the buffer effectively determines the memory requirements in the AS. For this reason, the source code can be recompiled with the following constants: Number of required signals (maximum of 7) Number of required associated values (maximum of 9) Number of messages to be buffered In the S7 program, the block can be configured with the following parameters: Advantages of this solution Use of an external time stamp for each signal Simulation of the connection or use of external connection monitoring Selection of the buffering method Stack buffer (in the event of overflow, the most recent messages will be lost) Ring buffer (in the event of overflow, the oldest messages will be lost) The completed block can be used in your own project. This will save costs when implementing the message concept. The block can be called repeatedly as a block instance and thus can be integrated into your own technological project hierarchy. Typical areas of application Suitable for all binary digital recorded messages, e.g. via digital inputs, or messages generated in separate program blocks. System messages cannot be buffered with this block. Entry ID: , V3.1, 02/2015 7

8 2 Solution 2.3 Hardware and software components used The application has been created with the following components: Hardware components Table 2 1 Component Qty. MLFB / Order number Note Rack 1 6ES7400-1TA01-0AA0 or equivalent Power supply PS ES7405-0KA00-0AA0 or equivalent S PN/DP 1 6ES7416-3ER05-0AB0 6ES7417-4HT14-0AB0 or equivalent S7-400 or S7-400-H CPU Software components Table 2-2 Component Qty. MLFB / Order number Note SIMATIC PCS 7 V ES AB17-0YA5 Only required for PCS7 configuration OR STEP 7 V5.4 SP4 1 6ES7810-4CC08-0YA5 Only for STEP 7 configuration WinCC 7.0 SP1 1 6AV6381-2BM07-0AX0 Only for STEP 7 configuration S7-SCL V5.3 SP5 1 6ES7811-1CC05-0YA5 Only for STEP 7 configuration Example files and projects The following list contains all files and projects that are used in this example: Table 2 3 Component Contents ALARM_7B.zip SCL source code PCS 7 library Example project Entry ID: , V3.1, 02/2015 8

9 2 Solution 2.4 Applicability Valid from SIMATIC PCS 7 V7.1. With later versions of SIMATIC PCS 7 (e.g. V8.1), migration of the project will be required (see Chapter 6.1). Entry ID: , V3.1, 02/2015 9

10 3 Function mechanisms 3 Function mechanisms General principle of operation The solution described in this document provides the option of storing alarms locally in the process control system with either the original time stamp or a time stamp from an external peripheral unit. It is aimed at preventing the loss of alarm messages which arise in the event of connection problems between the automation system and the operator system. All alarms that are to be stored must be sent to the OS via the "ALARM_7B" block. The "ALARM_7B" block receives a connection acknowledgment from the OS at periodic intervals. Depending on the type of acknowledgment, the alarms are either sent to the OS or stored until the connection has been restored. 3.1 Function and organization of the message buffer Organization of the message buffer The individual signals, time stamps and associated values are stored within a multidimensional array. The maximum number of signal changes to be stored (buffer size) is determined with the aid of the "BufferMax" constant. The data for a message are combined into a structure. The following information is stored in the structure of one single buffer space: Status of the buffer space (BOOL) Signals from 1 up to max. of 7 (ARRAY [1..SigMax] OF BOOL) Time stamps from 1 up to max. of 7 (ARRAY [1..SigMax] OF DT) Associated values from 1 up to max. of 9 (ARRAY [1..SdMax] OF REAL) The structures of the individual buffer spaces are in turn combined into an array: Buffer spaces from 1 to max. n (ARRAY [1..BufferMax] OF STRUCT) The following illustration shows symbolically the organization of the buffer: Fig. 3 1 Buffer [max] Buffer [..] State (BOOL) Buffer [2] State (BOOL) Signal (ARRAY[1..7] OF BOOL) SIG[1] SIG[2] SIG[3] SIG[4] SIG[5] SIG[6] SIG[7] Buffer [1] State (BOOL) Signal (ARRAY[1..7] OF BOOL) Timestamp (ARRAY[1..7] OF DATE_AND_TIME) SIG[1] SIG[2] SIG[3] SIG[4] SIG[5] SIG[6] SIG[7] TS[1] TS[2] TS[3] TS[4] TS[5] TS[6] TS[7] State (BOOL) Signal (ARRAY[1..7] OF BOOL) Timestamp (ARRAY[1..7] OF SD DATE_AND_TIME) (ARRAY[1..9] OF REAL) SIG[1] SIG[2] SIG[3] SIG[4] SIG[5] SIG[6] SIG[7] TS[1] TS[2] TS[3] SD[1] TS[4] SD[2] SD[3] TS[5] SD[4] TS[6] SD[5] SD[6] TS[7] SD[7] SD[8] SD[9] Signal (ARRAY[1..7] OF BOOL) Timestamp (ARRAY[1..7] OF SD DATE_AND_TIME) SIG[1] SIG[2] SIG[3] SIG[4] SIG[5] SIG[6] SIG[7] (ARRAY[1..9] OF REAL) TS[1] TS[2] TS[3] SD[1] TS[4] SD[2] SD[3] TS[5] SD[4] TS[6] SD[5] SD[6] TS[7] SD[7] SD[8] SD[9] Timestamp (ARRAY[1..7] OF DATE_AND_TIME) SD (ARRAY[1..9] OF REAL) TS[1] TS[2] TS[3] TS[4] TS[5] TS[6] TS[7] SD[1] SD[2] SD[3] SD[4] SD[5] SD[6] SD[7] SD[8] SD[9] SD (ARRAY[1..9] OF REAL) SD[1] SD[2] SD[3] SD[4] SD[5] SD[6] SD[7] SD[8] SD[9] Entry ID: , V3.1, 02/

11 3 Function mechanisms Contents of the individual arrays: Table 3-1 Designation Data type Description STATE BOOL Status of the buffer space 0 no current signal change entered 1 Signal change entered SIG ARRAY OF BOOL Signals 1 up to max. 7 TS ARRAY OF DT Time stamps of signals 1 up to max. 7 SD ARRAY OF REAL Associated values 1 up to max. 9 Principle of operation of the buffer The buffer works on the FIFO (First In First Out) principle. Consequently, the events with the oldest time stamp, which were the first to be written to the buffer, will also be the first to be read out and transmitted to the control system. The buffer can be used in two different ways: 1. Ring buffer (in the event of a buffer overflow, the oldest messages will be lost) 2. Stacked buffer (in the event of a buffer overflow, the most recent messages will be lost) If the ring buffer overflows, the signal image with the oldest time stamp will be discarded. This means that during a connection failure, the most recent messages will always be kept. Fig. 3 2 Entry ID: , V3.1, 02/

12 3 Function mechanisms In the case of the stack buffer, the memory is filled from the first buffer space to the last. If an overflow occurs, more recent signal changes will no longer be buffered. This means that during a connection failure, the oldest messages will always be kept. Fig. 3 3 Size of the allocation in working memory Depending on the configured constants in the SCL source, each instance of the alarm block occupies a different amount of space in the working memory of the CPU. In this context, the following memory space is occupied for each signal change to be buffered: Table 3-2 Tag Data type Size in the work memory STATE BOOL 2 bytes *) SIG ARRAY OF BOOL 2 bytes *) SD ARRAY OF REAL 4 bytes x SD MAX Timestamp ARRAY OF DT 8 bytes x SIG MAX *) In the case of a data type change, the addressing of the next tag always starts at a word boundary. Consequently, the status bit and the signal bits occupy 2 bytes each. Any unused bits in the working memory will be lost. The instance has a fixed size of 532 bytes. Hence the amount of working memory occupied by each instance data block of "ALARM_7B" can be calculated as follows: = ( ) If the source has been compiled with the constants (SigMax = 7, SdMax = 9, BufferMax = 10), 1492 bytes will be required for each instance data block of the block. The function block itself occupies 3546 bytes only once. Entry ID: , V3.1, 02/

13 3 Function mechanisms 3.2 Function of the connection monitor The connection between the automation system and the operator system is monitored with the aid of a periodic operation in the OS and analysis in the AS. The script writes a TRUE signal to an input tag at periodic intervals. If this input tag is written successfully to the AS, the block in the S7 program will trigger the transmission of all pending alarms and messages. At the end of the script cycle time (which can be defined with a block parameter), the block resets this tag back to FALSE. Fig. 3 4 S7-Connection good Value = 1 Set Value = 1 If the tag was not written successfully because of an interrupted connection, the input signal to the connection monitor will be FALSE. The block in the S7 program stores pending alarms and messages in the internal buffer. Fig. 3 5 S7-Connection bad Value = 0 Set Value = 1 Entry ID: , V3.1, 02/

14 4 Description of the block 4 Description of the block The "ALARM_7B" block is used to generate block-related messages with their associated values for seven signals, and to provide buffering of signal changes with time stamps in the event of connection problems. The "ALARM_7B" block is available either in the form of an SCL source or as a fully compiled and preconfigured block in an S7 library. The block s functionality can be adapted to your specific requirements. The following chapters refer to the version of the block as used for this description. 4.1 Function The block monitors the connection by checking an input signal which is written by an OS script at periodic intervals, and by resetting this input signal again at the end of the process. If this input signal cannot be written successfully by the OS, the block will identify an interruption of the connection. If a signal change (SIG_1 to SIG_7) is identified, all signals, time stamps and all associated values related to this signal change will be written to the buffer. After restoration of the connection, the buffered data will immediately be loaded again and transferred internally to the "Alarm_8P" block. If no connection is available, the signal changes will be written to the buffer as long as enough buffer spaces are available (stack buffer), or the earliest signal states will be overwritten (ring buffer). In the event of a buffer overflow, Signal 8 (buffer overflow message) will be set also. If the connection is restored after a failure, all buffered data will be sequentially transmitted to the OS (oldest first). The original time stamp remains unchanged and is displayed on the OS. The following settings can be configured on the block: Use of the block as stack or ring buffer Use of the CPU time or external time stamps Use of the integrated or an external connection monitoring function 4.2 Block I/Os The "ALARM_7B" block uses the "ALARM_8P" block internally. The existing block connections for "ALARM_8P" have been made available to the outside and extended by some further connections. Unlike the "Alarm_8P" block, the associated message values of "ALARM_7B" can only be used in REAL format. Data of the type ANY cannot be buffered. The use of any other format requires a type conversion or reprogramming of the block. Entry ID: , V3.1, 02/

15 4 Description of the block Fig. 4 1 Brief description of the block interfaces Table 4-1 Connection Type Data type Description EN_R I BOOL (Alarm_8P) 1 = ACK_STATE being updated SIG_1 SIG_7 I BOOL Alarm signals 1 to 7 ExtTimeOn I BOOL 0 = CPU time; 1 = External time stamp TS_1 TS_7 I DT External time stamp for signals 1 to 7 ID I WORD (Alarm_8P) Data channel for messages SEVERITY I WORD (Alarm_8P) Weighting of event ( , 0 = highest) SD_1 SD_9 I REAL Associated message values 1 to 9 RingBuff I BOOL 0 = Stacked buffer; 1 = Ring buffer ExtConnChOn I BOOL 0 = OS connection monitoring 1 = External connection monitoring ExtConnCh I BOOL Simulated or external connection status A8PDone O BOOL (Alarm_8P) 1 = Message generation completed A8PError O BOOL (Alarm_8P) 1 = Error during message generation Entry ID: , V3.1, 02/

16 4 Description of the block Connection Type Data type Description A8PStatus O WORD (Alarm_8P) Display of error information A8PAckState O WORD (Alarm_8P) Acknowledgment status of the 8 signals BufferLV O INT Number of stored signal changes BufferOV O INT 1 = Buffer overflow ConnStatus O BOOL 0 = No OS connection; 1 = Good OS connection qwpt O INT Write pointer to buffer space qrpt O INT Read pointer to buffer space Brief description of the ERROR and STATUS outputs (ALARM_8P) Table 4-2 ERROR STATUS Description Hex Dec. 0 0B 11 Warning: At least one signal change could not be sent Error in the pointer to the associated values SD_i: regarding data length or data type. associated values in the user memory cannot be accessed, e.g. due to a deleted DB or a range length error. The activated message will be sent without associated values. The actual parameter you have selected for SEVERITY is higher than the permitted range. The activated message is sent with SEVERITY = Communication has started. The message is being processed Communications problems: Connection canceled or no login available. For activated acknowledgment-triggered reporting: Temporary display, if none of the display devices handles acknowledgment-triggered reporting During initial calling the specified EV_ID is outside the permissible range. there is a formal error of the ANY pointer SD_i. the maximum buffer area available for the CPU per SFB 35 has been exceeded. 1 0A 10 The local user memory cannot be accessed (e.g. access to a deleted DB). 1 0C 12 When the SFB was called: An instance DB was specified that does not belong to SFB 35. specified a global DB instead of an instance DB EV_ID was already being used by one of the SFBs 31 or 33 to Out of working memory. H-system: Call of SFB during update The message with the specified EV_ID is disabled. Entry ID: , V3.1, 02/

17 4 Description of the block 4.3 Message behavior Example If there is a connection to the operator system, the message behavior corresponds to that of the "ALARM_8P" block. If no connection is available, the signal changes are written to the buffer of the block. It makes no difference whether only one or several signals are changing per cycle. Depending on the type of message buffer used stack or a ring buffer the messages will be output in different ways after the connection has been restored. The table below shows an example of how the signal changes are written to the buffer during a connection failure. When the buffer overflows, the oldest message will be overwritten (ring buffer) or no further signal changes will be stored (stack buffer). In this example, 10 signal changes are initiated while only 5 buffer spaces are available. The display of the output messages is only an example. The actual output of messages depends on the size of the buffer, the number of signal changes and the order of these signal changes. Table 4-3 Time stamp Signal SIG_1 SIG_2 SIG_3 SIG_4 SIG_5 1sec 2sec 3sec 4sec 5sec 6sec 7sec 8sec 9sec 10sec 11sec SIG_6 SIG_7 Overflow flag (SIG_8) The connection is restored at time 00:11 without further signal change. After that, the messages are loaded from the buffer and then the current signal status is output on the OS. Entry ID: , V3.1, 02/

18 4 Description of the block Message output when using a stack buffer The signal changes with time stamps 00:06 to 00:10 were not buffered. With the 6th signal change, the buffer overflow flag including a time stamp was set. If the connection is restored, the overflow flag will be reset. All signal changes that are stored in the buffer will be transmitted to the OS, followed by the currently changed signal states (example in Second 11). Table 4-4 Buffer space (Stack) Signal/ Time Sig_1 Sig_2 Sig_3 Sig_4 Sig_5 Sig_6 Sig_7 Sig_8 OVF flag 1 1 sec C 2 2 sec C 3 3 sec C 4 4 sec C 5 5 sec C The signal states are not stored 6 sec P C 7 sec P 8 sec G 9 sec G 10 sec G 1 11sec G G G G C C G After the connection is restored, the following messages, for example, are output. Table 4-5 Time stamp Message Status 00:01 SIG 1 Alarm C 00:02 SIG 2 Alarm C 00:03 SIG 3 Alarm C 00:04 SIG 4 Alarm C 00:05 SIG 5 Alarm C 00:06 Buffer overflow messages will be lost C 00:11 SIG 1 Alarm G 00:11 SIG 2 Alarm G 00:11 SIG 3 Alarm G 00:11 SIG 4 Alarm G 00:11 SIG 6 Alarm C 00:11 SIG 7 Alarm C 00:11 Buffer overflow messages will be lost G Entry ID: , V3.1, 02/

19 4 Description of the block Message output when using a ring buffer Signal changes 1 to 5 were overwritten by more recent signal changes. With the 6th signal change, the buffer overflow flag and its time stamp were set. If the connection is restored, the overflow flag will be reset. All signal changes that are stored in the buffer will be transmitted to the OS, followed by the currently changed signal states (example in Second 11). Table 4-6 Buffer space (Stack) Signal/ Time Sig_1 Sig_2 Sig_3 Sig_4 Sig_5 Sig_6 Sig_7 Sig_8 OVF flag Before 1 1 sec C 2 2 sec C 3 3 sec C 4 4 sec C 5 5 sec C 1 6 sec P P P P P C C 2 7 sec C 3 8 sec G 4 9 sec G 5 10 sec G After 11sec G G After the connection is restored, the following messages, for example, are initiated. Table 4-7 Time stamp Message Status 00:06 SIG 1 Alarm C 00:06 SIG 2 Alarm C 00:06 SIG 3 Alarm C 00:06 SIG 4 Alarm C 00:06 SIG 5 Alarm C 00:06 SIG 6 Alarm C 00:06 Buffer overflow messages will be lost C 00:07 SIG 7 Alarm C 00:08 SIG 1 Alarm G 00:09 SIG 2 Alarm G 00:10 SIG 3 Alarm G 00:11 SIG 4 Alarm G 00:11 Buffer overflow messages will be lost G Entry ID: , V3.1, 02/

20 4 Description of the block 4.4 Startup behavior During startup (when the block is called by OB100, OB101 or OB102), the message buffer is reset. In the case of a restart no signal changes will be stored. Please take note also of the behavior of the ALARM_8P block during startup or restart. Entry ID: , V3.1, 02/

21 5 Using the block 5 Using the block This application example provides you with the following options to download, test and use the block: As an SCL source (for use with PCS 7 versions earlier than V7.1) As a library with SCL sources and compiled and pre-configured blocks (created with PCS 7 V7.1 or STEP 7 V5.4 SP4) As an example project for testing the block (created with PCS 7 V7.1, can also be used on later PCS 7 versions) Note With later versions of SIMATIC PCS 7 (e.g. V8.1), migration of the project will be required (see Chapter 6.1). The block can be used with PCS 7 as well as STEP 7. When using STEP 7, however, be sure to call the block not via OB1, but by a watchdog interrupt OB (OB30 - OB38). Later versions of PCS 7 and STEP 7 can be used but a migration of the project will then be required. 5.1 Generating the block with the SCL source Together with this application you receive the source for the described block. This source is not know-how protected. You can therefore extend and adapt the programming of the block to your specific requirements. In order to generate the "ALARM_7B" function block, please proceed as follows: Entry ID: , V3.1, 02/

22 5 Using the block Table 5-1 No. 1. Import the SCL source file. Description 1. Open an existing project or create a new one. 2. In the S7 program for the CPU, select the "Sources" folder. 3. Execute the menu command "Insert>External Source ". 4. Navigate to the storage location of the downloaded SCL source file and import the file "ALARM_7B.SCL". 2. Copy the required system functions The "ALARM_7B" block calls the following system functions which must be copied into the block folder of the S7 program before you start to compile the SCL source. You will find these blocks in the standard library in the folder "System Function Blocks": READ_CLK (SFC 1) RD_SINFO (SFC 6) Alarm_8P (SFB 35) 3. Define the block symbol Before you can generate the block from the source, an FB number must be assigned to the block symbol. 1. Use the SCL Editor to open the "ALARM_7B" source file. 2. Open the Symbol Table in the SCL Editor (Options > Symbol Table) 3. Enter the "ALARM_7B" symbol with a free FB number. In this example, the number "FB 701" has been selected. 4. Save your settings and close the Symbol Table Entry ID: , V3.1, 02/

23 5 Using the block No. Description 4. Configure the block constants The size of the buffer or the occupied buffer space in the AS can be influenced with the aid of some constants in the declaration part of the SCL source file. Configure the following constants as required: SigMax (max. 7 signals): Number of signals used. This will not affect the occupied buffer space, since after a data type change in the DB, the addressing is always continued at the word boundary. Hence, 1 bit to 16 bits always occupy the storage space available for one word. SdMax (max. 9 associated message values): Number of buffered associated message values. BufferMax: Number of signal changes to be buffered. ScTrigTime: Reset time of the monitoring signal. This constant determines the time (in seconds) that elapses until the input for connection monitoring will be reset. This constant should be set slightly larger than the update time of the periodic script on the OS. 5. Compile the SCL source file Compile the source file. The new "ALARM_7B" block will be generated in the block folder of the S7 program. Entry ID: , V3.1, 02/

24 5 Using the block No. 6. Configuring messages Description Signal 8 of the block is reserved for the buffer overflow message. Signals 1 to 7 can be used and configured for your own purposes and as desired. 1. In the context menu for the block, select the command "Specific Object Properties>Messages ". 2. Configure the buffer overflow message for Signal 8, e.g.: Text: Buffer overflow One or more messages lost Class: Process Message With Acknowledgment 3. Configure Signals 1 to 7 according to your requirements. 7. "ALARM_7B" block The block can now be used in your S7 program. Entry ID: , V3.1, 02/

25 5 Using the block 5.2 Using the block from the library The enclosed library includes the following components: SCL source for the block The compiled and pre-configured block (7 signals, 9 associated values, 10 buffer spaces, 1s cycle for connection monitoring) You can use the block just as it was created. You only need to customize the messages for signals 1 to 7. The number of signals and associated message values and the size of the message buffer can only be changed in the source file. The block will then have to be recompiled. Table 5-2 No. 1. Open library Description Start SIMATIC Manager. Select the menu command "File > Retrieve " to retrieve the library "ALARM_7B_lib.zip". Then open the library. 2. Copying objects Copy the SCL source and the "ALARM_7B" block into your project or your project library. In addition, copy the following blocks, which are required for execution, into your S7 program. You will find them in the standard library in the folder "System Function Blocks": READ_CLK (SFC 1) RD_SINFO (SFC 6) Alarm_8P (SFB 35) Entry ID: , V3.1, 02/

26 5 Using the block No. 3. Configure messages Description The compiled block is already configured with messages. You just need to customize the messages for signals 1 to 7 according to your own requirements. Signal 8 of the block is reserved for the buffer overflow message. 1. In the context menu for the block, select the command "Specific Object Properties>Messages ". 2. Configure Signals 1 to 7 according to your requirements. 4. "ALARM_7B" block The block can now be used in your S7 program. Entry ID: , V3.1, 02/

27 5 Using the block 5.3 CFC configuration Table 5-3 No. Description 3. CFC chart Use the CFC Editor to create a new CFC chart or open a previously created one. Insert the "ALARM_7B" block into the CFC chart. 4. Connections Establish the block connections or configure the inputs as follows: SIG1..SIG7 [BOOL]: Triggering signals SD_1..SD_9 [REAL]: Associated message values RingBuff [BOOL]: Buffer type (0 = stack buffer, 1 = ring buffer) ExtTime [DATE_AND_TIME]: A possible external time stamp (ExtTimeOn must be set to 1) ExtConnCheck [BOOL]: A possible external connection monitoring function (ExtConnCheckOn must be set to 1) Note The block connections are described in chapter 4.2 Block I/Os. Entry ID: , V3.1, 02/

28 5 Using the block No. 5. Messages Description The messages can be configured individually for each block added to a CFC chart. To do so, open the context menu of the block and select the command "Object Properties ". Click the "Messages " button to open the usual dialog box for the configuration of messages. Entry ID: , V3.1, 02/

29 5 Using the block 5.4 Script for connection monitoring To enable the block in the AS program to identify a connection failure, a periodic action must be configured in the OS. Each "ALARM_7B" block generates on the operator system the tag "CheckConnState", which is used to monitor the connection. This tag must be periodically written with a "1" by means of an operation. The tag will then be reset again in the S7 program. A connection failure is present, if this tag is no longer set by the OS. In this case, the incoming messages will be buffered in the AS. It doesn t matter whether you set the tags with a C-action or VBS-action. In this example only the VBS variant is considered. For proper functioning of the script, the following preconditions must be met: "ALARM_7B" blocks are configured in the CFC program. The CFC charts have been compiled and loaded. The OS project has been compiled and loaded. To create the script, proceed as follows: Table 5-4 No. Description 1. Open the Global Script VBS Editor Open the OS project. Doubleclick "Global Script > VBS-Editor" to open the editor. 2. Create a new action Use the menu command "File > New > Action" to create a new action. Entry ID: , V3.1, 02/

30 5 Using the block No. 3. Source code Description All "ALARM_7B" blocks in the AS program generate the tag "<tagprefix>.checkconnstate" on the OS. The tag prefix depends on the specific configuration. Declare these tags with the following lines of code: Dim CCS1 Set CCS1.HMIRuntime.Tags("<tagprefix>.CheckConnState") Write the value 1 to the tag: CCS1.Value = 1 CCS1.Write The program for three "ALARM_7B" blocks looks like this: 4. Set the trigger Start the dialog to set the trigger for this action "Options > Info/Trigger". Open the "Trigger" tab, select "Cyclic" and then click the "Add" button. Enter a name and select a cycle time of 1s, for example. Note The cycle time for the execution of the action should be set slightly less than the monitoring time in the block. See the parameter ScTrigTime in the chapter 5.1 Generating the block with the SCL source. Entry ID: , V3.1, 02/

31 5 Using the block No. 5. Save the action Description Save the action and enter a name. Entry ID: , V3.1, 02/

32 6 Demo Project 6 Demo Project You can use the demo project to test the block and to analyze its behavior. The demo project uses the external connection monitoring function for simulation purposes. This enables simulation of the behavior of the block in the event of a connection failure, without having to stop the ongoing connection. The triggering of the alarm signals and the configuration of the alarm block were implemented with the aid of an auxiliary block which provides the operator system with the tags and the signals of the "ALARM_7B" block. You will require at least SIMATIC PCS 7 V7.1 to be able to open the project. With later versions of SIMATIC PCS 7, migration of the project will be required (see following description). The demo project has been configured for use with PLCSIM. If you wish to test the block with real hardware components, the hardware configuration and the connection configuration of the project must be adapted to your specific circumstances. 6.1 Start-up To start the demo project with PLCSIM, proceed as follows: No. Description 1. Open the demo project with SIMATIC PCS 7 V7.1 Start SIMATIC Manager. Select the menu command "File > Retrieve " to retrieve the demo project "ALARM_7B_Demo.zip". Then open the project. Entry ID: , V3.1, 02/

33 6 Demo Project Table 6-1 No. Description 2. Open the demo project with SIMATIC PCS 7 V Start SIMATIC Manager. Select the menu command "File > Retrieve " to retrieve the demo project "ALARM_7B_Demo.zip" Then open the project. 2. When the PCS 7 V7.1-based project is opened, the following migration dialog opens. Confirm it with "YES" 3. The WinCC migration dialog then opens. Select the appropriate language here and uncheck the check box for quick migration. 4. Click on the "Migrate" button. Entry ID: , V3.1, 02/

34 6 Demo Project No. 3. The project opens in SIMATIC PCS 7 Description 5. Compile your CFCs - the following dialog appears. Confirm it by clicking on the "YES" button. 6. Compile the OS to migrate the picture data. Entry ID: , V3.1, 02/

35 6 Demo Project No. 4. Start PLCSIM Description Load the PC station, the hardware configuration and the S7 program into the CPU. Activate the "RUN-P" mode for the PLCSIM. 5. Open the OS project In the SIMATIC Manager, select the OS project and then click the menu command "Edit >Open Object". The Runtime function can be activated after WinCC Explorer has been started and OS project has been loaded. Note: When you use PLCSIM, you must adapt the "Logical device name" of the particular connection in the tag manager. Entry ID: , V3.1, 02/

36 6 Demo Project 6.2 Description of the user interface Fig. 6 1 The figure below shows the user interface of the demo project in Runtime: The OS display shows the following elements: Connection simulation Buffer type settings Triggering of alarm signals Entry of associated message values Display of the buffer status Output of messages in AlarmControl The selection and radio buttons, text boxes and the status displays are linked to the tags of the auxiliary block. You can control the individual elements with your mouse or modify the associated message values via your keyboard. Entry ID: , V3.1, 02/

37 6 Demo Project Connection simulation The auxiliary block is configured so that the alarm block uses the external connection monitoring function by default. It can be operated with the selection boxes: Activate Simulation: Turns the simulation on and off Connection On/Off: Simulates the connection Fig. 6 2 Buffer type and time stamp The buffer type and the use of the time stamps can be set with the aid of these radio buttons. Fig. 6 3 Buffer Type - Ring: The block will be used as a ring buffer Buffer Type - Stack: The block will be used as a stack buffer Timestamp External: The time stamps at the block inputs will be used Timestamp CPU: The CPU time will be used Entry ID: , V3.1, 02/

38 6 Demo Project Alarm signals For each signal, a pre-configured message including the associated message values can be triggered with a mouse click. Depending on the connection status, the messages will be displayed in the AlarmControl display or written to the buffer. Fig. 6 4 Associated message values The associated message values can be entered into the input fields. The values will be output in the appropriately configured messages or buffered. Fig. 6 5 Entry ID: , V3.1, 02/

39 6 Demo Project Status The status field provides the following information: Status of the (simulated) connection Buffer level Positions of the write and read pointers Buffer status (good / overflow) Fig. 6 6 Note Output of messages Please note that the graphical display of the buffer only shows the buffer level. The actual position of the buffered messages may be different. The messages are displayed in the AlarmControl window after triggering when there is an ongoing connection or after being read out from the message buffer. The control window is pre-configured with a short-term archive list. Fig. 6 7 Entry ID: , V3.1, 02/

40 7 Literature 7 Literature 7.1 Related documents This list is by no means complete and merely reflects a selection of suitable literature. Table 7 1 Subject area /1/ STEP 7 SIMATIC S7-300/400 /2/ STEP 7 SIMATIC S7-300/400 Title Automating with STEP 7 in STL and SCL Author: Hans Berger Publicis MCD Verlag, ISBN: Automation with STEP 7 in KOP and FUP Author: Hans Berger Publicis MCD Verlag, ISBN: Internet links This list is by no means complete and merely reflects a selection of suitable information. Table 7 2 Subject area \1\ Reference to the article \2\ Siemens Industry Online Support \3\ Manual S7-SCL V5.3 for S7-300/S7-400 \4\ Manual CFC for SIMATIC S7 Title Entry ID: , V3.1, 02/

41 8 History 8 History Table 8 1 Version Date Change V1.0 02/2005 First edition ALRM7PBT V2.0 08/2009 New, improved version ALARM7VB V3.0 06/2013 Complete reworking ALARM_7B V3.1 01/2015 Update to SIMATIC PCS 7 V8.1 Entry ID: , V3.1, 02/