Technical data

Table Of Contents
System Software for S7-300/400 System and Standard Functions - Volume 1/2
A5E00709327-01
16-1
16 SFCs for Distributed I/Os or PROFINET IO
16.1 Triggering a Hardware Interrupt on the DP Master with
SFC 7 "DP_PRAL"
Description
With SFC 7 "DP_PRAL," you trigger a hardware interrupt on the DP master from
the user program of an intelligent slave. This interrupt starts OB40 on the DP
master.
Using the input parameter AL_INFO, you can identify the cause of the hardware
interrupt. This interrupt identifier is transferred to the DP master and you can
evaluate the identifier in OB40 (variable OB40_POINT_ADDR).
The requested hardware interrupt is uniquely specified by the input parameters
IOID and LADDR. For each configured address area in the transfer memory, you
can trigger exactly one hardware interrupt at any time.
How the SFC Operates
SFC 7 "DP_PRAL" operates asynchronously, in other words, it is executed over
several SFC calls. You start the hardware interrupt request by calling SFC 7 with
REQ=1.
The status of the job is indicated by the output parameters RET_VAL and BUSY,
see Meaning of the Parameters REQ, RET_VAL and BUSY with Asynchronous
SFCs. The job is completed when execution of OB40 is completed on the DP
master.
Note
If you operate the DP slave as a standard slave, the job is completed as soon as
the diagnostic frame is obtained by the DP master.