Siemens SIMATIC NET S7-1200 User Manual

Configuration and operation
5.7 Types of transmission, event classes, triggers
CP 1243-1 DNP3, CP 1243-1 IEC
40 Operating Instructions, 02/2014, C79000-G8976-C312-02
The send buffer
The send buffer is the data buffer on the CP for storing the values of events. The send buffer
has a maximum size of 64000 events. The configured number of events is divided equally
among all configured and enabled communications partners. The "Data buffer size"
parameter for the size of the send buffer is described in the section Communication with the
CPU (Page 49).
The frame memory operates chronologically; in other words, the oldest frames are sent first
(FIFO principle). When the maximum number of events is reached and the frames could not
be sent, the oldest values are overwritten.
If a connection to a communications partner is interrupted, the values of the events are
retained in the buffer. When the connection returns, the buffered frames are sent.
With the DNP3 CP, additional conditions for sending the events can be specified:
● A maximum number of events in the send buffer, configurable for each event class.
● A configurable maximum storage period for events in the send buffer.
This configuration of these conditions is described in the section Ethernet interface (X1) >
Advanced options (Page 43).
Types of transmission
Depending on your CP type, you have the following transmission types available:
●
Transfer after call
The current value of the data point is entered in the image memory of the CP. New
values of a data point overwrite the last stored value in the image memory.
After being called by the communications partner, the current value at the time is
transferred.
●
Event class
The value is entered in the send buffer triggered as an event. If unsolicited transfer is
enabled by the master, the value is transferred unsolicited.
You will find details of the event classes in the following sections.
The type of transmission is specified for each data point in the data point configuration in
STEP 7 with the "Type of transmission" or "Event class" parameter.
Event classes for the DNP3 protocol
The process data of the various event classes is handled as follows:
●
Event class 1 / event class 2
Each value change is entered in the send buffer in chronological order.
The evaluation of the classification (1 or 2) must be handled by the master.
●
Event class 3
Only the current value at the time the trigger condition was met is entered in the image
memory and overwrites the last value stored there.

Siemens SIMATIC NET S7-1200 Specifications

General

Supply voltage	24 V DC
Protection class	IP20
Product type designation	S7-1200
Transfer rate	10/100 Mbit/s
Number of ports	4
Power consumption	2.5 W
Operating temperature	0 °C to 60 °C
Mounting type	DIN rail
Switching capacity	1 Gbps

Summary

Application and properties

Communications services

Details supported communication services like DNP3 and IEC 60870-5 protocols.

Other services and properties

Configuration examples

Requirements for use

Hardware requirements

Lists required hardware and firmware versions for DNP3 and IEC setups.

Software requirements

Specifies necessary configuration and online function software, like STEP 7 versions.

LEDs and connectors

LEDs

Details the function and meaning of various LEDs on the module.

Electrical connections

Describes power supply and Ethernet interface connections.

Installation, connecting up, commissioning

Important notes on using the device

Notices on use in hazardous areas

Provides specific warnings for explosion hazards and hazardous environments.

Notices regarding use in hazardous areas according to ATEX

Details ATEX requirements for enclosures and operational conditions.

Notices regarding use in hazardous areas according to UL HazLoc

Outlines UL HazLoc suitability and warnings for hazardous locations.

Installation

Installing, connecting up and commissioning

Configuration and operation

Addressing and network configuration

Covers required information for master addressing and VPN connections.

Configuration in STEP 7

Details configuring modules, networks, redundant systems, and steps in STEP 7.

Configuring datapoints and messages (e-mails)

Explains configuring user data, PLC tags, and sending e-mail notifications.

Datapoint types

Lists supported data point types for DNP3 and IEC protocols with S7 data types.

Types of transmission, event classes, triggers

Covers data storage, transmission types, event classification, and triggers.

Notes on configuring individual functions

Provides detailed configuration notes for communication, SNMP, and Ethernet interface options.

Diagnostics and upkeep

Diagnostics options

Outlines available diagnostics methods like LEDs, STEP 7 tabs, and online functions.

Downloading firmware

Explains how to find and download new firmware versions for the CP.

Module replacement