Processing Interrupts - Siemens SIMATIC S5 Equipment Manual

R 02/92

9.4.8 Processing Interrupts

See the description of function block FB 157 for the processing of interrupts. Only the differences
will be covered here.
Data word Dw n+7 in the working data block of function block FB 158 corresponds to the ABIT
parameter of function block FB 157.
DW n+7:
X, y X =
x =
A block of the alarm–controlled processing is called when an interrupt occurs (based on the
jumper setting). The scratchpad flags must be saved at the beginning of this block, and reloaded
from it again at the end.
in a data block at the beginning, and reloaded again at the end.
DW n
DW n+l
DW n+2
DW n+3
DW n+4
DW n+5
DW n+6
DW n+7
The interru~t processing block contains the call of function block
working data block mu~ be supplied with the "KB" command before this function block is called.
After function block FB 158 is called, the ST parameter indicates which channel triggered the inter-
rupt. A special "interrupt program" can now be processed.
When an interrupt occurs during the processing of function block FB 158 in the cyclic program, the
group alarm on the bus is deleted again in FB 158 during reading of byte 7. This means that no
organization block of alarm–controlled processing is called. However, function block FB 158 does
update the control bits (DR n+6) so that an alarm program can then be called based on the inter-
rupt bits. Evaluation must be performed, however, before the cyclic control information is loaded in
data word DR n+6.
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255, y = 255 Module without interrupt
o, o
y = to 7 Reset appropriate alarm bits in the system
data
Programming Instructions
KS
KY
KM
KY
FB 158. Parameter DW n of the
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