Description The size of the main memory of a SIMATIC CPU depends on the following parameter settings:
Number of messages in the diagnostics buffer of the CPU
Maximum number of communication jobs
Size of the process-image input and output areas
Amount of local data for all priority classes
It is particularly effective to change these parameters with CPU types that have small main memories.
A significant part of the main memory used by the CPU for programs is taken up by the diagnostics buffer of the CPU. Here you have to decide how many messages are required by your application in the diagnostics buffer.
Fig. 1: Setting options for the number of messages in the diagnostics buffer of the CPU
You can also change the number of communication jobs. You can read the requirement in your application in the "Communication jobs of which currently loaded" line (Fig. 4). Change the maximum number as necessary. Here, you must take into account a reserve of approx. 30% is achieved.
You can also change the message texts in this dialog.
Fig. 2: Communication job and local data setting options
If you pay attention to assign the IO addresses of the IO modules as far as possible without gaps, you can reduce the process image for inputs/outputs.
Fig. 3: Setting options for the process image
You can see how the main memory is occupied online in the Properties of the CPU. In the "Memory" tab you select the field with the "main memory code" values (click in the field) and then click the "Main memory details" button.
Fig. 4: Occupation of the main memory of CPU 412
Note
More information about the structure and calculation of the main memory is available in the device manual entitled "Automation System S7-400 CPU Specifications", in the section "Overview of the Memory Concept of the S7-400-CPUs".
Keywords
Storage capacity, Compression, Safety matrix, Program memory, Code memory
How many connections and communication jobs do SIMATIC S7-300 and S7-400 support simultaneously?
Description
The maximum number of connections and communication jobs that an S7-300 or S7-400 supports depends on the CPU and CP used.
Each connection requires connection resources for the end point or for the transition point (e.g. CP) on the stations concerned. The number of connection resources is CPU/CP-specific. If all the connection resources of a communication partner are occupied, no new connection can be set up.
An overview of the services and quantity frameworks that the CPUs with integrated PN interface support is available in Entry ID: 18909487.
Information on which communication connections of the Industrial Ethernet CPs need connection resources of the CPU is available in Entry IDs: 42480411 and 42480718.
Information on the maximum permitted number of simultaneous connections via CP is available in the relevant CP manuals in the chapter entitled "Performance Data".
An overview of the services and quantity frameworks that the Industrial Ethernet CPs of S7-300 and S7-400 support is available in Entry IDs: 16767769 and 15368142.
Which connection resources are occupied in the S7-400 CPU for communication connections and services of the Industrial Ethernet CP?
Description One connection resource is required in the S7-400 CPU for each of the following communication connections of the Industrial Ethernet CP:
Communication connection
Service
TSAP
PG communication via S7 server
Web diagnostics, e.g. for displaying the diagnostics buffer of the CPU
Set time in CPU 318
Applets, e.g. to read MLFB or status of the CPU
0x01
System connection via S7 server
FTP server (read and write access to file DBs)
FTP client (read and write access to file DBs)
Applets (read and write access to CPU data)
0x03
System connection
SEND and RECEIVE
0x0F
If the SEND / RECEIVE, FTP and Web diagnostics services are used simultaneously in the Industrial Ethernet, 3 connection resources of the S7-400 CPU are occupied.
An Industrial Ethernet CP occupies a maximum of 3 connection resources in the S7-400 CPU, i.e. maximum one connection resource for:
PG communication via S7 server (TSAP=0x01)
System connection via S7 server (TSAP=0x03)
System connection SEND/RECEIVE (TSAP=0x0F)
How many breakpoints can you insert when debugging a program?
The maximum number of breakpoints that can be used is determined by the CPU used.
Four breakpoints:
All SIMATIC S7-400 CPUs
All SIMATIC S7-300 CPUs as from firmware V3.x
CPU 318-2 DP
Two breakpoints:
All SIMATIC S7-300 CPUs (except CPU 318-2 DP) with firmware lower than V3.x
If you have used up your breakpoint resources, you must first reset (delete) a breakpoint before you can set it at another point. Here you must note that breakpoints already run through continue to occupy resources. If you exceed the maximum number of breakpoints that can be used, you get an error message "D062 / D063" (resources exceeded).
What are the system limits in an F CPU for safe bidirectional data communication via S7 Communication?
Description: This entry gives you an overview of the system limits of S7 Communication.
The following figures show the basic configuration of S7 Communication between F CPUs via Industrial Ethernet. Bidirectional data communication is via an S7 connection.
Fig. 01
Alternatively, bidirectional data communication can be via two separate S7 connections. In this way, you can structurally separate the send and receive channels, for example.
Fig. 02
The system limit of S7 Communication is determined by the following parameters:
Max. number of connections supported by the CPU.
Max. number of S7 connections that can be configured per interface.
Max. number of instances supported by the CPU.
Max. number of connections supported by the CPU The following table shows the maximum number of connections supported by the F CPUs.
F CPU
Max. number of connections
IM 151-8F CPU
12
CPU 315F-2 PN/DP
16
CPU 317F-2 PN/DP
32
CPU 319F-3 PN/DP
32
CPU 416F-2 DP
64
CPU 416F-3 PN/DP
64
WinAC RTX F 2009
64
Max. number of S7 connections that can be configured The following table shows the maximum number of S7 connections supported by the F CPUs.
F CPU
Max. number of S7 connections that can be configured
IM 151-8F CPU
10
CPU 315F-2 PN/DP
14
CPU 317F-2 PN/DP
16
CPU 319F-3 PN/DP
16
CPU 416F-2 DP with CP443-1 Adv.
62
CPU 416F-3 PN/DP
30
WinAC RTX F 2009
Via CP5611: 6
Via CP5613: 48
Via CP1616: 30
Via IE general: 14
Max. number of instances The following table shows the maximum number of instances supported by the F CPUs.
F CPU
Max. number of instances
IM 151-8F CPU
32
CPU 315F-2 PN/DP
32
CPU 317F-2 PN/DP
32
CPU 319F-3 PN/DP
32
CPU 416F-2 DP with CP443-1 Adv.
Firmware version < V5.2: 1800 (can be configured: 600 preset)
Firmware version V5.2 onwards: 4000 (can be configured: 600 preset)
CPU 416F-3 PN/DP
600 (internal interface)
CPU 416F-3 PN/DP with CP443-1 Adv.
Firmware version < V5.2: 1800 (can be configured: 600 preset)
Firmware version V5.2 onwards: 4000 (can be configured: 600 preset)
WinAC RTX F 2009
600 (can be configured: 300 preset)
Example: In a CPU 319F-3 PN/DP, you select S7 Communication via TCP/IP for safe bidirectional data communication. Depending on whether the data communication is via one or two configured S7 connections, you can configure another 15 or 14 S7 connections.
The fail-safe communication blocks "F_SENDS7" and "F_RCVS7" are called in the CPU user program for safe bidirectional data communication via S7 connections. These blocks internally call the system function blocks SFB8 "USEND" and SFB9 "URCV" respectively. In this way, the user data and associated acknowledgments are sent and received. An instance data block is assigned to each SFB8 "USEND" and SFB9 "URCV" system function block. Thus, the number of instance data blocks (= instances) is identical to the number of communication jobs.
This means that in the case of safe bidirectional data communication, at least four communication jobs are executed and four instances are needed. In this case, with the CPU 319F-3 PN/DP there remain 28 free instances.
In the user program of the CPU 319F-3 PN/DP, you can call a maximum of 16 fail-safe communication blocks "F_SENDS7" or F_RCVS7", because the maximum of instances is limited to 32.
In the case of safe bidirectional data communication, the CPU 319F-3 PN/DP can communicate with a maximum of 8 F CPUs.
Calculation for safe bidirectional data communication in the CPU 319F-3 PN/DP: 8 "F_SENDS7" + 8 "F_RCVS7" = 16 fail-safe communication blocks
8*("USEND" + "URCV") + 8*("USEND" + "URCV")
= 16 "USEND" + 16 "URCV" = 32 communication jobs or instances
Note: The safety function is foremost with F CPUs. Therefore, the system limit of S7 Communication is determined not only by the number of communication connections, but also by the response times achieved. If the required response times are not achieved because of the number of communication connections, the remedy is to
Reduce the number of communication connections.
Use a larger and faster CPU.
How can you determine the size of the load memory and main memory of a SIMATIC S7-300/400 CPU?
Description: The example shown here explains how you can use your project to determine the size of the load memory and main memory in order to define the size of the memory cards needed, for example.
Open the project and mark the block folder.
Right-click and select "Object Properties".
Fig. 01
In the new window you select the "Blocks" tab.
Fig. 02
You can also determine the size of the load memory by adding the user program and the system data (red marking),
for example, 428 bytes + 710 bytes = 1138 bytes
The memory card used in the S7 CPU must have this size at least.
The required size of the CPU's main memory is displayed directly (yellow marking).
Keywords: Memory size, MMC, MC
Where do you find information on transmission times on the PROFIBUS or Industrial Ethernet?
Description: The transmission time on the PROFIBUS and Industrial Ethernet depends on the cycle times of the implemented blocks (S7-300 or S7-400 CPU, PROFIBUS CP, Industrial Ethernet CP) and the volume of data to be transferred.
The following entry gives you a tool for determining transmission time for typical configurations on PROFIBUS 22180794.
The following entry gives you a tool for determining transmission time for typical configurations on the Industrial Ethernet: 22180793.
What is a hardware interrupt and how do they work in the S7-400 system?
Instructions: Events can occur in the current process which require responses which are quicker than are possible in the current program cycle. Events also occur which do not last long enough to be identified in the current program cycle. Therefore, there is hardware interrupt processing in SIMATIC S7-400 controllers.
Together with:
analog input modules (AI),
digital input modules (DI) and
function modules (FM)
with hardware interrupt capability, a program which is adapted to suit the event can be called in real time.
Hardware interrupts approximate to interrupts.
This entry is intended to serve as a guide to hardware interrupts in S7-400 CPUs.
General:
If an alarm-triggering event occurs during program processing, the operating system calls the assigned alarm OB, interrupting the processing of the program cycle or lower-priority program blocks. The alarm-triggering event (or events (multiple bits can be set)) is/are specified more precisely via the alarm OB's temporary local data. The temporary local data can be evaluated by the user program in the alarm OB.
If there is no alarm OB in the CPU when an alarm-triggering event occurs, the CPU goes into STOP mode.
Hardware interrupt-triggering events in the different modules:
Analog input modules: A value can be monitored in analog input modules with hardware interrupt capability. The hardware interrupt can be configured to be triggered off if values drop below or rise above specified thresholds. More information about the individual analog input modules is available in the manual "Programmable Logic Controller S7-400 Module Data" in Entry ID 1117740 in chapter 5.
Digital input modules: Individual bits can be monitored in digital input modules with hardware interrupt capability. The hardware interrupt can be configured to be triggered off in the event of a negative and/or positive edge to the bit. More information about the individual digital input modules is available in the manual "Programmable Logic Controller S7-400 Module Data" in Entry ID: 1117740 in chapter 4.
Function modules: Since function modules with hardware interrupt capability perform a wide range of different tasks, allowing the hardware interrupts to be configured for different events, it is advisable to consider the FM 450-1 counter module by way of an example.
The FM 450-1 enables a hardware interrupt to be triggered off in the CPU whenever comparison values are reached, or in the event of an over-run or under-run and/or if the counter passes through zero. More information about the FM 450-1 module is available in the manual "FM 450-1 Counter Module - Setup and Configuration" in Entry ID: 1118412. More information about the other function modules is available in the module-specific documentation.
Warning:
Many function modules require special parameterization software which is supplied with the function module with the corresponding documentation. Hardware interrupt-triggering events can only be configured together with STEP 7 and the parameterization software.
(Communication modules): There is no way of configuring hardware interrupt-triggering events in the communication modules themselves. However, the communication modules can forward hardware interrupts from modules with hardware interrupt capability to the CPU. Example:
You can install a CP 443-5 Ext (6GK7 443-5DX01-0XE0) in your CPU's subrack. You can configure the CP 443-5 Ext as the master and link an IM 153-1 (6ES7 153-1AA02-0XB0) to it. You can then install a module with hardware interrupt capability into the IM 153-1 (see Fig. 01). If a hardware interrupt then occurs in this module, the assigned alarm OB is called by the CPU.
Fig. 01
Alarm OBs in the SIMATIC S7-400: SIMATIC S7-400 CPUs contain the alarm OBs 40 to 47. Each module can be assigned to the required alarm OB in the HW Config (Module object properties > Addresses > Hardware interrupt activated:) . Temporary local data is made available in each alarm OB. The channel/bit where the hardware interrupt event occurred is specified through this temporary local data.
You can find the description of the alarm OBs in STEP 7 whenever you create a new alarm OB in the CPU's block folder (right click > Insert new object > Organization block > OB[40...47]), select the newly created OB and then press "F1". This opens the S7 Help for the alarm OBs. Needless to say, if there is an alarm OB already present, you can select an alarm OB straight away and then press "F1".
More information about the module-specific evaluation of the local data is available in the manual "Programmable Logic Controller S7-400 Module Data" in Entry ID: 1117740 Chapter 4 (Digital Modules) and Chapter 5 (Analog Modules) or in the special manuals relating to the function modules.
There are 2 alarm OBs (40 and 41) in the CPU 318-2DP. All other S7-300 CPUs only possess the alarm OB 40.
More information about hardware interrupts for S7-300 is available in Entry ID: 23657941
Configuring a hardware interrupt: Hardware interrupts can be configured in the hardware configuration under the properties for the modules with alarm capability.
You can find an example of how to calculate the alarm response time for the S7-400 in the manual "Programmable Logic Controller S7-400 CPU Data" in Entry ID: 14016796 section 5.8 ff.
The modules with hardware interrupt capability can also be configured during an ongoing program cycle by means of system functions SFC 55 (WR_PARM), SFC 56 (WR_DPARM) and SFC57 (PARM_MOD). You can find out how to configure the corresponding data records with the system functions in the manual "Programmable Logic Controller S7-400 Module Data" in Entry ID: 1117740.
Information about the different SFCs is available in the S7 Online Help and in the manual "System Software for S7-300/400 System and Standard Functions" in Entry ID: 1214574 in section 7.1.
Warning:
System functions SFC 55, SFC56 and SFC 57 cannot be used with PROFINET IO.
Blocking, delaying, releasing hardware interrupts:
Hardware interrupts can be blocked, delayed and released again by means of system functions SFC 39 (DIS_IRT IRT_FUNC), SFC 40 (EN_IRT IRT_FUNC), SFC 41 (DIS_AIRT IRT_FUNC) and SFC 42 (EN_AIRT IRT_FUNC).
Information about the different SFCs is available in the S7 Online Help and in the manual "System Software for S7-300/400 System and Standard Functions" in Entry ID: 1214574 in chapter 12.
What restrictions are there for active jobs when communicating with SFC 58 / SFC 59 and SFB 52 / SFB 53 via PROFIBUS DP and PROFINET IO?
Configuration Notes: System functions and blocks SFB52 "RDREC" / SFC59 "RD_REC" (read record) are used to read data records of a component (module) of a DP slave/PROFINET IO device. System functions and blocks SFB53 "WRREC" / SFC58 "WR_REC" (write record) are used to write data records to a component (module) of a DP slave/PROFINET IO device.
Depending on the CPU used, the number of active jobs of the system functions and blocks SFB53/SFC58 and SFB52/SFC59 is limited.
The following table provides information about how many active jobs of the system functions and blocks SFB53/SFC58 and SFB52/SFC59 your CPU supports simultaneously.
System function/
system block
SFB 52 "RDREC"/
SFB 53 "WRREC"
SFC 59 "RD_REC"/
SFC 58 "WR_REC"
Explanation
Data record from DP slave, PROFINET IO device
Data record from DP slave
IM154 (ET 200pro)
IM151 (ET 200S)
IM147 (ET 200X)
4 jobs together with SFC 58/59
4 jobs together with SFB 52/53
CPU 312, CPU 313, CPU 314
CPU 315, CPU 316
4 jobs together with SFC 58/59
4 jobs together with SFB 52/53
CPU 317, CPU 319
CPU 318-2
8 jobs together with SFC 58/59
8 jobs together with SFB 52/53
CPU 41x1)
8 jobs each per PROFIBUS DP segment and PROFINET IO system
8 jobs each per PROFIBUS DP segment and PROFINET IO system
1) The number of simultaneous jobs on external PROFIBUS DP segments or PROFINET IO systems must not exceed 32 jobs per SFC/SFB.
Example:
With a CPU 414-2DP, a maximum of 48 jobs per SFC/SFB can be executed at the same time (8 each on the two PROFIBUS DP segments that are connected to the integrated interfaces of the CPU, and 32 on external PROFIBUS DP segments and PROFINET IO systems).
Rules:
There are no restrictions for simultaneous jobs in the subracks (CR, ER). The SFCs run synchronously via the backplane bus. Any number of synchronous SFCs can be called.
If you are operating multiple communication partners on the PROFIBUS network, then please make sure that never more than the specified jobs are active at the same time. Here one SFC/SFB can run several CPU cycles long.
The restrictions listed in this entry for the active jobs of the system functions and blocks SFB53/SFC58 and SFB52/SFC59 also apply to the blocks that call these system functions and blocks internally. These include the blocks FM_CS, PID_FM and FMCS_PID, for example. Example: When communicating with an FM 355 (4 channels parameterized) via the FMCS_PID block, 4 read jobs are occupied.
Note:
System functions SFC58/59 are available on all CPUs.
