The management of SIMATIC communication resources depends on the type of controller. When using the S7-300, many details must be respected before the maximum number of devices that can be configured can be connected. The communication management of s7-1500 has simpler regulations.
Connection resources of S7-300 and s7-1500
Example 1: connecting with S7-300 configuration
Example 2: configuration connection and non configuration connection with S7-300
Example 3: configuration with s7-1500, non configuration and programmed connection
Connection resources of S7-300 and s7-1500
Connection resources: CPU 1516-3 pN / DP 1) CPU 317-2 pN / DP2)
Resources (total) 256 32
Resource (reserved) 10 (PG / HMI / WEB) 2 (PG / OP)
Available resources for S7 and HMI 246 3) 30
Available resources for OUC (open user communication) 16
The maximum number of resources through ontology integration interface is 128 324)
Maximum number of connection resources for each connected HMI device
31
1) It includes the web communication connection of S7-300 / s7-1500 and OPC UA connection of s7-1500.
2) Two of the 32 resources of S7 communication are reserved for pg / Op. In addition, 16 S7-300 connections are used, including OUC and up to 80 web communication connections.
3) Of the 246 resources, all communication types are considered, including OPC UA and the largest 80 web connections.
4) In S7-300, the resources of OUC, S7 and web communication are managed separately.
For the CPU, each communication connection requires a connection resource as a management element during the connection. Each CPU has a specific number of connection resources, which are occupied by different communication services (PG / op, S7 communication, OUC).
Using S7-300, the CPU determines the reasonable number of connection resources. The maximum number of resources connected can be extended by adding CP. In S7 / op communication, CP occupies resources in S7-300 CPU. In the CPU, multiplexing resources are occupied by a CP. If there is no multiplexing, the connection is taken from the CPU quota by 1:1. PG connections always take up a resource in the CPU.
Using s7-1500, CPU defines the upper limit of effective connection resources for complete automation system. The CPU itself contributes part of these connection resources. More resources come from CP and cm. Regardless of the number of CP and cm added, the total number of connection resources cannot exceed the upper limit set by the CPU type.
These three examples are based on CPU 317-2 pN / DP (order number: 6es7317-2ek14-0ab0) and CPU 1516-3 pN / DP (order number: 6es7516-3an01-0ab0).
Example 1: connecting with S7-300 configuration
Figure 1
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S7 connection to CP2
OUC (open user communication) with CP1
PROFINET connection
HMI connection
When the communication service logs in, the CPU connection resources are reserved in chronological order.
In order to avoid the occupation of communication resources, we only manage various communication services in chronological order. For some services, we can choose to reserve connection resources.
S7 and op connections share connection resources using multiplexing mode, which is why the three S7 connections of CP2 in Figure 1 are not shown in the table. For PG connections, a resource is always required. Multiplexing can be enabled automatically when an S7 connection is created through CP.
Example 1 shows the available and required resources to create a connection.
Up to 16 S7 connections can be configured via the CPU. The other 16 resources are provided for other types of communication, but are not really reserved.
In addition, through two CPS, each can be configured with 16 S7 connections.
A resource is occupied by HMI communication.
In CP1, four resources are used for OUC.
