Siemens SIMATIC S7-300 FM 350-1, Manual

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Operating Modes, parameters and commands
7.5 Triggering of a Hardware Interrupt
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01
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Enabling the Hardware Interrupt
You enable the interrupts for the module in the parameterization screens when configuring
the hardware and you decide whether the module is to initiate a diagnostics interrupt and/or
a hardware interrupt.
Hardware Interrupt OB, OB 40
If a hardware interrupt occurs, the user program is interrupted, the data is transferred from
the module to the start information of OB40 and OB40 is called. The hardware interrupt is
acknowledged by exiting OB 40.
If no OB 40 is programmed, the CPU goes to STOP. If you then switch back to RUN, the
hardware interrupt requirements are deleted.
Start Information
The temporary variable OB40_POINT_ADDR is written in the start information of OB 40.
The variable OB40_POINT_ADDR (Bytes 8 to 11) consists of four bytes. The information
about the event that has initiated the hardware interrupt is entered in Bytes 8 and 9.
The table shows which bits are set for which interrupt. All unlisted bits are not significant and
are set to zero.
Table 7- 47 Assignment of the Bits of the Variable OB40_POINT_ADDR
Byte Bit Meaning: Interrupt in the case of...
0 Opening the gate
1 Closing the gate
Overflow (at Count mode)
2
Measured value outside limits (at Measure mode)
Underflow (at Count mode)
3
End of measurement (at Measure mode)
4 Reaching Comparison value 1 in the up direction
5 Reaching Comparison value 1 in the down direction
6 Reaching Comparison value 2 in the up direction
8
7 Reaching Comparison value 2 in the down direction
0 Zero pass
5 Setting the counter with an external signal (synchronization)
9
7 Latch