Technical data

Table Of Contents
Organization Blocks
System Software for S7-300/400 System and Standard Functions - Volume 1/2
1-28
A5E00709327-01
1.15 Communication Redundancy Error OB (OB73)
Note
The communications redundancy error OB (OB73) is only available in firmware
version V2.0.x for the CPU 417-4H.
Description
The operating system of the H CPU calls OB73 when the first loss of redundancy
occurs in a fault-tolerant S7 connection (Fault-tolerant S7 connections only exist for
S7 communication. For more information, see "S7-400 H Programmable Controller,
Fault-Tolerant Systems."). If a loss of redundancy occurs for additional fault-
tolerant S7 connections, there are no more OB73 starts.
Another OB73 start will not occur until you have restored redundancy for all S7
connections that were fault tolerant.
The CPU does not change to the STOP mode if a start event occurs and the OB73
is not programmed.
Local Data of the CPU Redundancy Error OB
The following table contains the temporary (TEMP) variables of the communication
redundancy error OB. The default names of OB73 have been used as the variable
names.
Variable Type Description
OB73_EV_CLASS BYTE Event class and IDs:
B#16#73, B#16#72
OB73_FLT_ID BYTE Error code (possible values: B#16#E0)
OB73_PRIORITY BYTE Assigned priority class: default 25
OB73_OB_NUMBR BYTE OB number (73)
OB73_RESERVED_1 WORD Reserved
OB73_INFO_1 WORD (irrelevant to the user)
OB73_INFO_2 WORD (irrelevant to the user)
OB73_INFO_3 WORD (irrelevant to the user)
OB73_DATE_TIME DATE_AND_TIME DATE_AND_TIME at which the OB was called
The following table shows which event caused OB73 to be started.
OB73_FLT_ID Start Event of OB 73
B#16#E0 Loss of redundancy in communication/problem eliminated