SM331; AI 8x12 Bit Getting Started part 1: 4 -20mA
Getting Started, 11/2006, A5E00253410-02
9-1
Hardware interrupt
9
9.1 Hardware interrupt
Overview
A special feature of the SM331 AI8x12bit is its capability to trigger hardware interrupts. Two
channels (0 and 2) can be correspondingly configured.
Hardware interrupts generally trigger alarm organization blocks in the CPU. In our example,
OB40 is called.
The limit values for hardware interrupts have to be specified in mA.
Example:
You have connected a pressure sensor with a 4-20mA transducer to channel 0. Here the
limit values should be specified in mA and not in Pascal (Pa).
limit values
In order to trigger a hardware interrupt, the limit values have to be within the nominal values
of the measuring mode.
Example:
If wire break detection (3.6 mA) is enabled, and you choose 3.5 mA for the low limit value,
this setting is accepted by the system. A hardware interrupt will not be triggered because the
diagnostic alarm is always triggered first.
In our example, 2 channels (sensor 1 and 2) are configured with the following limits:
● Lower limit value 6 mA
● Upper limit value 18 mA
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