Analog Modules
4-75
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
4.17 Interrupts of the Analog Modules
Introduction
In this Section, the interrupt behavior of the analog modules is described. The
following interrupts exist:
• Diagnostic interrupt
• Hardware interrupt
Note that not all analog modules have interrupt capability or they are only capable
of a subset of the interrupts described here Refer to the technical specifications of
the modules, starting at Section 4.18, to determine which analog modules have
interrupt capability.
The OBs and SFCs mentioned below can be found in the online Help for STEP 7,
where they are described in greater detail.
Enabling interrupts
The interrupts are not preset – in other words, they are inhibited without
appropriate parameter assignment. Assign parameters to the Interrupt Enable in
STEP 7 (refer to Section 4.7).
Diagnostic interrupt
If you have enabled diagnostic interrupts, then active error events (initial
occurrence of the error) and departing error events (message after
troubleshooting) are reported by means of an interrupt.
The CPU interrupts the execution of the user program and processes the
diagnostic interrupt block (OB 82).
In the user program, you can call SFC 51 or SFC 59 in OB 82 to obtain more
detailed diagnostic information from the module.
The diagnostic information is consistent until such time as OB 82 is exited. When
OB 82 is exited, the diagnostic interrupt is acknowledged on the module.
Hardware interrupt with trigger “Upper or lower limit exceeded”
Define a working range by setting parameters for an upper and lower limit value. If
the process signal (for example, the temperature) leaves this working range, the
module triggers a hardware interrupt, provided the interrupt is enabled.
The CPU interrupts execution of the user program and processes the hardware
interrupt block (OB 40).
In the user program of OB 40, you can set how the programmable logic controller
is required to react to a limit value being surpassed or not being reached.
When OB 40 is exited, the hardware interrupt is acknowledged on the module.
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