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S7-400 CPU 41x -- Product information -- Background and system information
All-round protection with Industrial Security - System Integrity
What are the differences between OPEN MODBUS / TCP Redundant V1 and OPEN MODBUS / TCP Redundant V2?
What is the difference between "normal routing" and data record routing?
Which SIMATIC S7-300/S7-400 modules support the NTP time-of-day message and how do you activate this kind of time synchronization?
Which manufacturer ID, in other words OUI (Organizationally Unique Identifier), does SIEMENS AG use for the MAC addresses of network-compatible devices?
What should you watch out for when adding components or changing their parameters using CiR (Configuration in Run)?
Which IO controllers and IO devices support the following functions: IRT, prioritized startup, MRP, PROFIenergy, Shared device, I device and clock-synchronized mode?
Which types of connection/protocols do the S7-300/400 CPUs and the CPs support by default?
Which PROFINET nodes support automatic commissioning (device replacement without interchangeable medium) in the case of topological configuration and device replacement without topological configuration?
Behavior of the CPU after power off without back-up battery
I/O addressing with DP slaves
Which PROFINET nodes support the extended PN diagnostics and what do you have to configure?
What is the difference between a restart (warm restart), cold restart and hot restart of a S7-400 CPU?
Which SIMATIC S7 modules support the "Direct Data Exchange" function (internode communication)?
What properties, advantages and special features does the S7 Basis Communication offer?
What properties, advantages and special features does the global data communication offer?
Which entries deal with consistent data in conjunction with distributed I/O?
What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
Which modules support the S7 routing function?
CPU does not work in RUN
What does "Correction factor" mean in the "Diagnostics/Clock" tab of the CPU's Properties dialog?
What is multicomputing mode and what are the differences to operating in the segmented subrack?
Differing information on the requirement of offline/ online memory
How can I get an overview of the S7-400 memory concept?
S7-300 CPU 31x -- Product information -- Background and system information
What is the emergency address (emergency IP) of a CPU and when is this enabled or disabled?
All-round protection with Industrial Security - System Integrity
What are the differences between OPEN MODBUS / TCP Redundant V1 and OPEN MODBUS / TCP Redundant V2?
What is the difference between "normal routing" and data record routing?
Which SIMATIC S7-300/S7-400 modules support the NTP time-of-day message and how do you activate this kind of time synchronization?
Which manufacturer ID, in other words OUI (Organizationally Unique Identifier), does SIEMENS AG use for the MAC addresses of network-compatible devices?
What should you watch out for when using the alarm numbering procedure?
Which IO controllers and IO devices support the following functions: IRT, prioritized startup, MRP, PROFIenergy, Shared device, I device and clock-synchronized mode?
What is the maximum number of parameters that can be assigned to an FC and FB in the S7-300 CPU?
Which types of connection/protocols do the S7-300/400 CPUs and the CPs support by default?
Which PROFINET nodes support automatic commissioning (device replacement without interchangeable medium) in the case of topological configuration and device replacement without topological configuration?
Which PROFINET nodes support the extended PN diagnostics and what do you have to configure?
Why is only a warm start available for S7-300?
Which SIMATIC S7 modules support the "Direct Data Exchange" function (internode communication)?
Which entries deal with consistent data in conjunction with distributed I/O?
What properties, advantages and special features does the S7 Basis Communication offer?
What properties, advantages and special features does the global data communication offer?
What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
Which modules support the S7 routing function?
How can you obtain an overview of the memory concept of SIMATIC S7-300 CPUs and C7 devices?
Retentivity behavior of S7-300 CPU 31x and complete devices C7-6xx with MMC
Status of the run-time meter after overall reset
Why does the retentivity behavior of the S7-300 CPUs and C7 devices without MMC (Micro Memory Card) influence the contents of the variables?
Local data addressing with S7-300 / S7 400
S7 300 run-time meter doesn't give any value
Industrial Ethernet S7-300/400 CPs -- Product information -- System description (protocols)
How are the communication resources assigned in the S7-300?
How do you load the 3D, CAx and ePLAN data for the SIMATIC products?
What are the differences between OPEN MODBUS / TCP Redundant V1 and OPEN MODBUS / TCP Redundant V2?
What should you watch out for when you enable the "SNMP" function in the configuration of the security module?
Which security modules support the DNS function?
What should you watch out for when enabling and using the security functions of CP343-1 Advanced and CP443-1 Advanced?
What should you watch out for when upgrading from previous modules to the successor module CP443-1 or CP443-1 Advanced?
How do you verify the authenticity of the Siemens modules CP343-1 and CP443-1?
What should you watch out for when operating a port of CP343-1, 6GK7343-1CX10-0XE0 and 6GK7343-1EX30-0XE0 with firmware V2.1 or higher, with 10 Mbit/s half duplex?
Which IO controllers and IO devices support the following functions: IRT, prioritized startup, MRP, PROFIenergy, Shared device, I device and clock-synchronized mode?
Where do you procure the firmware extension for the CP 343-1 ERPC for database connection?
Which SIMATIC S7-300/S7-400 modules support the NTP time-of-day message and how do you activate this kind of time synchronization?
Which modules can you use when implementing software redundancy?
Which types of connection/protocols do the S7-300/400 CPUs and the CPs support by default?
Which PROFINET nodes support automatic commissioning (device replacement without interchangeable medium) in the case of topological configuration and device replacement without topological configuration?
Which PROFINET nodes support the extended PN diagnostics and what do you have to configure?
Using C-PLUG with network components and SIMATIC CPs
What properties have the communication services and protocols that can be used in the Industrial Ethernet network?
Behavior of the communication processors during data transfer via TCP connections without RFC 1006
What should you watch out for with the ICMP Redirect (Internet control message protocol) function regarding the IP address of the router used for Industrial Ethernet CPs?
What should you pay attention to with the autonegotiation function for negotiating the LAN mode in Industrial Ethernet CPs?
What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
Which modules support the S7 routing function?
In the case of open TCP/IP communication via Industrial Ethernet using T blocks with IE CPs and CPUs, why are different amounts of messages sent when the maximum length of 1452 bytes of user data is transferred?
What properties, advantages and special features does the ISO protocol offer?
What properties, advantages and special features does the UDP protocol offer?
What properties, advantages and special features does the ISO-on-TCP protocol offer?
What properties, advantages and special features does the S7 protocol offer?
What properties, advantages and special features does the TCP protocol offer?
What are the requirements for disabling the PROFINET CBA interface for CP443-1EX40?
"Time Wait" with TCP connection setup
What are the different data block lengths for the various protocols of Send/Receive communication?
What is RFC1006 and what do I need this service for?
Meaning and function of the "Keep Alive" in TCP connections
S7-1200 CPU 12xx -- Setting up and parameterizing hardware -- Initializing and parameterizing modules
Which settings do you have to make in the TIA Portal to read out messages and status information over the CPU's web server and display them in the web browser?
What is the meaning of the system constants in STEP 7 (TIA Portal) with S7-1200/1500?
How can the CPU analog inputs of the SIMATIC S7-1200 also measure currents of 0-20mA?
How do you program the "GET" and "PUT" instructions in the user program of the SIMATIC S7-1200 CPU in order to transfer more than 160 bytes of data?
Why must you never remove a memory card when the S7-300/S7-400/S7-1200 CPU is in operation (RUN)?
How in STEP 7 (TIA Portal) do you access the unstructured data types bit-by-bit, byte-by-byte or word-by-word and symbolically?
How does startup work in an S7-1200?
What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
How can you prevent data loss of runtime-generated parameters when updating your S7-1200 PLC program?
How can you share runtime-generated parameters between several S7-1200 PLCs with a KTP Basic Panel?
How can you change the IP address of an S7-1200 without using STEP 7 Basic?
How can you delete the IP address and reset your S7-1200 to factory settings using the SIMATIC MC memory card (2MB or 24MB)?
How can you download to a network of several S7-1200 PLCs with the same IP address?
How can you reset the IP address of your S7-1200 PLC using STEP 7 Basic software?
ET 200S (standard modules) -- Product information -- System description
Which SIMATIC S7-300/S7-400 modules support the NTP time-of-day message and how do you activate this kind of time synchronization?
Which hardware and software components do you need to establish communication between SIMATIC S7 stations and third-party devices using the MODBUS RTU protocol?
Which memory cards are used in the interface modules in the ET 200 with CPU functionality?
Which manufacturer ID, in other words OUI (Organizationally Unique Identifier), does SIEMENS AG use for the MAC addresses of network-compatible devices?
What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
Which IO controllers and IO devices support the following functions: IRT, prioritized startup, MRP, PROFIenergy, Shared device, I device and clock-synchronized mode?
Which PROFINET nodes support automatic commissioning (device replacement without interchangeable medium) in the case of topological configuration and device replacement without topological configuration?
Which PROFINET nodes support the extended PN diagnostics and what do you have to configure?
Backing up the IM 151/CPU data on Micro Memory Card
What is the meaning of the terms "sinking" (German: "P-schaltend") and "sourcing" (German: "M-schaltend") in digital modules of SIMATIC?
ET 200pro -- Product information -- System description
Which manufacturer ID, in other words OUI (Organizationally Unique Identifier), does SIEMENS AG use for the MAC addresses of network-compatible devices?
What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
Which connectors and cables can you order for the distributed IO systems ET 200eco, ET 200eco PN and ET 200pro?
Which IO controllers and IO devices support the following functions: IRT, prioritized startup, MRP, PROFIenergy, Shared device, I device and clock-synchronized mode?
Which PROFINET nodes support automatic commissioning (device replacement without interchangeable medium) in the case of topological configuration and device replacement without topological configuration?
Which PROFINET nodes support the extended PN diagnostics and what do you have to configure?
Industrial Ethernet PC CPs -- Product information -- System description
How do you load the 3D, CAx and ePLAN data for the SIMATIC products?
Why does the CP 1616 / CP 1604 as PROFINET IO controller and/or PROFINET IO device not go into data exchange mode after the configuration has been successfully loaded?
What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
How can you display the security status of the CP1628 over the Online View in the Security Configuration Tool (SCT)?
What are the requirements for changing from CP1613 A2 to CP1623?
Which IO controllers and IO devices support the following functions: IRT, prioritized startup, MRP, PROFIenergy, Shared device, I device and clock-synchronized mode?
In which order should you install the software of the Development Kit DK16xx PN IO in order to load the configuration or firmware of the CP1616 via NCM PC?
Which modules support the S7 routing function?
What are the options for connecting a PC station to Industrial Ethernet or PROFIBUS via the SIMATIC NET OPC server?
What is the difference between SoftNet and HardNet communication processors?
What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
Part number:

Configuration Notes
With CIDR, there is no fixed assignment of an IP address to a network class and possible subnetting in other networks or supernetting of several networks in a class. There is only one network mask that splits the IP address into a network part and a host part.

The CIDR function (Classless Inter Domain Routing) thus includes subnetting and supernetting.

The following Industrial Ethernet CPs support the subnetting and supernetting functions:

  • 6GK7343-1EX21-0XE0 as from FW V1.2
  • 6GK7343-1EX30-0XE0
  • 6GK7343-1GX21-0XE0 as from FW V1.1
  • 6GK7343-1GX30-0XE0
  • 6GK7343-1GX31-0XE0
  • 6GK7343-1CX10-0XE0
  • 6GK7343-1FX00-0XE0
  • 6FL4343-1CX10-0XE0
  • 6GK7443-1EX20-0XE0
  • 6GK7443-1EX30-0XE0
  • 6GK7443-1EX40-0XE0 as from FW V2.4
  • 6GK7443-1EX41-0XE0
  • 6GK7443-1GX20-0XE0
  • 6GK7443-1GX30-0XE0

The following CPUs with integrated PROFINET interface support the subnetting and supernetting functions:

  • IM151-8(F) PN/DP CPU
  • IM154-8(F) CPU
  • CPU314C-2 PN/DP
  • CPU315(F)-2 PN/DP as from FW V2.3
  • CPU317(F)-2 PN/DP as from FW V2.3
  • CPU319(F)-3 PN/DP
  • CPU412-2 PN
  • CPU414(F)-3 PN/DP
  • CPU416(F)-3 PN/DP
  • CPU412-5H PN/DP
  • CPU414-5H PN/DP
  • CPU416-5H PN/DP
  • CPU417-5H PN/DP
  • S7-1200 CPUs as from FW V1.0

The following Industrial Ethernet PC modules support the subnetting and supernetting functions:

  • CP1616 as from V2.0
  • CP1604 as from V2.0
  • CP1613 (A2) as from SW V7.1
  • CP1623
  • CP1628
  • CP1612 and IE General

For the remaining Industrial Ethernet PC modules like CP1613 (A2) < SW V7.1, CP1604 V1, CP1616 V1 and CP1512 it is only possible to configure the "Subnetting" function. It is not possible to configure the "Supernetting" function for these modules in STEP 7 / NCM PC. This is prevented in STEP 7 / NCM PC by an error message (see Fig. 05).

In these modules that support the TCP/IP protocol it is possible to set both the IP address and the associated subnet mask in the hardware configuration of STEP 7. The IP address and associated subnet mask are entered in the Properties window of the CP's or CPU's Ethernet interface. After inserting the Industrial Ethernet CP or CPU with integrated PN interface in the hardware configuration, you are offered the following default settings (see Fig. 01) in the Properties window of the CP's or CPU's Ethernet interface.

  • IP Address: 192.168.0.1
  • Subnet mask: 255.255.255.0


Fig. 01

If you wish to change these default settings for the IP address and subnet mask, you need information about the connection between classes of IP addresses and subnet masks. The following demonstrates the connection between classes of IP addresses and subnet masks.

Connection between class of the IP address and subnet mask
In principle there are 5 classes of IP addresses. These are the classes A to E. Each class has its own subnet mask. The connections are given in the table below.
 
Class Class bits IP address range Subnet mask Network share Node share
A 0xxxxxxx 0.x.x.x - 127.x.x.x 255.0.0.0 1 byte 3 bytes
B 10xxxxxx 128.0.x.x - 191.255.x.x 255.255.0.0 2 bytes 2 bytes
C 110xxxxx 192.0.0.x - 223.255.255.x 255.255.255.0 3 bytes 1 byte
D

1110xxxx

224.0.0.0 - 239.255.255.255

---

Multicast addresses

E 1111xxxx 240.0.0.0 - 255.255.255.255 ---

Reserved addresses
(for future purposes)

Class A network
IP addresses from Class A begin with the bit sequence 0-...; for example, the IP address range lies between 0.x.x.x and 127.x.x.x.
The subnet mask identifies the range that includes the address information for identifying the subnet. In Class A networks the first byte, that is to say the first 8 bits, corresponds to the IP address of the subnet address. Thus Class A networks are defined by the following subnet mask: 255.0.0.0 = 1111 1111 0000 0000 0000 0000 0000 0000. The last three bytes (24 bits) of the IP address identify a node in this subnet.

The total number of Class A networks can be calculated as follows:

  • 28-1-2 = 27-2 = 126 networks (since the IP address always begins with the bit sequence 0-..., 0.0.0.0 and 127.0.0.0 are not permitted)

The number of computers in a Class A network can be calculated as follows:

  • 224-2 = 16 777 214 computers (x.0.0.0 -> network address and x.255.255.255 -> broadcast address are not permitted)


Fig. 02

Class B network
IP addresses from Class B begin with the bit sequence 1-0-... and the address range lies between 128.0.x.x and 191.255.x.x. In Class B networks the first two bytes, that is to say the first 16 bits correspond to the IP address of the subnet address. Thus Class B networks are defined by the following subnet mask: 255.255.0.0 = 1111 1111 1111 1111 0000 0000 0000 0000. The last two bytes (16 bits) identify a node in this subnet.

The total number of Class B networks can be calculated as follows:

  • 216-2 = 214 = 16384 networks (since the IP address always begins with the bit sequence 1-0...)

The number of computers in a Class B network can be calculated as follows:

  • 216-2 = 65534 computers (x.x.0.0 -> network address and x.x.255.255 -> broadcast address are not permitted)


Fig. 03

Class C network
IP addresses from Class C begin with the bit sequence 1-1-0... and the address range lies between 192.0.0.x and 223.255.255.x. In Class C networks the first three bytes, that is to say the first 24 bits correspond to the IP address of the subnet address. Thus Class C networks are defined by the following subnet mask: 255.255.255.0 = 1111 1111 1111 1111 1111 1111 0000 0000. The last byte (8 bits) identifies a node in this subnet.

The total number of Class C networks can be calculated as follows:

  • 224-3 = 221 = 2 097 152 networks (since the IP address always begins with the bit sequence 1-1-0...)

The number of computers in a Class C network can be calculated as follows:

  • 28-2 = 254 computers (x.x.x.0 -> network address and x.x.x.255 -> broadcast address are not permitted)


Fig. 04

Class D subnetwork
The class D subnetwork consists of special addresses that are used for multicast addressing.

Summary
The splitting up of IP addresses in network share and node share leads to the following conclusions:

  • A Class A network is larger than a Class C network, because there is a greater address area available for addressing the computers.

  • There are much less Class A networks than Class C networks because the address area of the subnets is smaller.

Reserved addresses

  • The Class A network address 127.x.x.x is reserved for the Loopback function of all computers, which means that
    all IP addresses that have the value 127 in the first byte may only be used for internal tests of computers.

  • The value 255 in the last byte (Byte 4) is reserved asBroadcast Address. Thus, for example, the address 140.80.255.255 is a broadcast address to all nodes in the Class B network 140.80.0.0.

  • The following ranges are reserved for private networks. All IP addresses from these ranges are not routed in the Internet.
    10.0.0.0 - 10.255.255.255
    172.16.0.0 - 172.31.255.255
    192.168.0.0 - 192.168.255.255

Until now, the connection between the class of the IP address and subnet mask has been explained. Furthermore, it is possible to extend the subnet mask with the so-called "subnetting" procedure.

Subnetting
Subnetting can be implemented in a Class A network, for example. It is possible to divide the computers of this Class A network into further logical units (subnets). We will observe the Class A network 86.x.x.x as an example. The subnet mask of this Class A network is 255.0.0.0 (1111 1111 0000 0000 0000 0000 0000 0000). The address area can be divided further into logical subnets by extending the subnet mask by 1 bit. The subnet mask is then 255.128.0.0 (1111 1111 1000 0000 0000 0000 0000 0000).

This means the following for addressing:

  • Only the addresses 86.0.0.1 to 86.127.255.254 can communicate directly with each other, that is without router, because these computers have the same value (in this case "0") in the first bit after the subnet mask.

  • Only the addresses 86.128.0.1 to 86.255.255.254 can communicate directly with each other, that is without router, because these computers have the same value (in this case "1") in the first bit after the subnet mask.

  • The address area of the computers in this Class A network has been divided into two subnets.

Conclusion
By extending the subnet mask you can divide the address area of the computers into more logical units (subnets). The address area has been divided into two subnets in the example. By adding more bits you can quickly multiply the number of subnets.

Supernetting
Supernetting is the grouping together of multiple networks with partially the same network share in one subnet. The underlying technology is the opposite to subnetting and in principle means a procedure for addressing a large number of nodes within one subnet. With supernetting the node share of a network class is increased. Thus the network share of this network class is decreased.
We will observe the Class C network 192.168.178.0 as an example. The subnet mask of this Class C network is 255.255.255.0 (1111 1111 1111 1111 1111 1111 0000 0000). Now 2 bits are added to the node share. The subnet mask is then 255.255.252.0 (1111 1111 1111 1111 1111 1100 0000 0000).

  • The lowest IP address of the network to be assigned is
    192.168.176.1 (1111 1111.1111 1111. 1011 0000. 0000 0001)

  • The highest IP address of the network to be assigned is
    192.168.179.254 (1111 1111.1111 1111. 1011 0011. 1111 1110)

  • The addresses 192.168.176.1 to 192.168.179.254 can communicate directly with each other, this means without router.

Requirement
The use of "Supernetting" requires that the modules in the network support the "Classless Inter Domain Routing" (CIDR) function.

Note
If the module configured in STEP 7 does not support the subnetting function or the supernetting function, then use of these functions is prevented by the following error message in STEP 7


Fig. 05


Fig. 06

The STEP 7 Online Help indicates that the subnet mask in the incorrect format as follows.


Fig. 07

 Entry ID:2073614   Date:2013-07-24 
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