The digital input module DI80-N serves for

connection of eight 3-wire PNP/NPN sensors

(IEC 61131, Type 3). The sensors are not

powered via the module, but via a reverse-polarity protected auxiliary energy which is fed

separately via the terminals to the channels

1 … 4 (group 1) and 5 … 8 (group 2). The input groups are galvanically isolated from each

other.

The input behavior is parameterized via the

Fieldbus master. Possible parameters are

switching behavior (PNP or NPN), polarity,

substitute value strategy, wire-break monitoring, short-circuit monitoring and flutter monitoring.

Flutter monitoring detects and reports procedually unusual signal patterns, for example

too frequent fluctuation of the input signal between 0 and 1. The occurrence of such

signal patterns is an indication of faulty sensors or process-related instabilities.

For each input channel there is a parametrizable monitoring window. With the first signal

change of the input signal, the monitoring window is started. If the input signal changes

more often within the monitoring window than

the configured number of signal changes, this

is recognized as a flutter error. If no flutter error is detected within the monitoring window,

then the monitoring window is started again

with the next signal change.

If a flutter error occurs, the current signal status is entered in the process image and the

value status of the signal is set to invalid.

In addition, the diagnostic information flutter

error is entered and an incoming diagnostic

alarm is triggered. The value status and diagnostic information can be evaluated and processed in the user program. If no more fluttering of the input signal has been recognized

within the triple monitoring window, the diagnostic entry is removed and an outgoing diagnostic alarm is triggered. The status of the

current signal in the process image is set to

valid.

■ Input module for 3-wire sensors (NPN and

PNP)

■ Supply of sensors reverse polarity protected via auxiliary power