Siemens SIMATIC FM 353, Manual

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Programming the Technological Functions
6-44
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0
6.5 Interrupts
Interrupt processing
The FM 353 can generate process interrupts and diagnostic interrupts. You can
process these interrupts only in an interrupt OB (OB 40 or OB 82). If an interrupt is
generated without the associated OB having been loaded, the CPU goes to STOP
(refer to the manual entitled
Programming with STEP 7 ).
Interrupt servicing is enabled in the following stages:
1. General Interrupt Enable for the entire module:
− Select the module in the hardware configuration.
− Enable diagnostic and/or process interrupts with Edit > Object Properties >
Basic Parameters (also see Figure 5.2).
− Select the OB number for the process with Edit > Object Properties > Ad-
dresses .
− Save and compile the hardware configuration.
− Load the hardware configuration into the CPU.
2. Enable the events for the process interrupt in the machine data.
Evaluating a process interrupt
When the FM 353 generates a process interrupt, variable OB40_POINT_ADDR (or
the corresponding variable in another process interrupt OB) contains the following
information:
Table 6-10 Contents of doubleword OB40_POINT_ADDR
Byte Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 in-process
measuring
On-the-fly
block chang
Length
measurement
terminated
Position
reached
1
2
3
The reason for the interrupt is made available in byte 0.
Lost process interrupts
If servicing of a process interrupt in the process interrupt OB has not yet been ter-
minated, the module “makes a note” of all subsequent process interrupt events. If
an event re-occurs before a process interrupt could be generated, the module gen-
erates the diagnostic interrupt “process interrupt lost”.