07AI90-S ABB GJR5251200R0202, CS31, Analog Input module

Description:

The module 07 AI 90-S is an analog input module with 4 input channels for 4...20 mA. The module is part of the safety-related PLC (Advant Controller 31-S). It is used in safety-relevant automation systems to be classified under requirement classes 1...4 according to DIN V 19250. It is used as a remote module and linked to the central unit 07 KT 94-S via the CS31 system bus. The CS31 system bus interface is electrically isolated from the other circuitry of the module. The input signals of the module 07 AI 90-S are read in by the AC31 central unit using special safety-related connection elements (CEs).

As the following Figure shows, the analog value processing is largely configured in dual-channel technique. In this way, the following tasks can be fulfilled:
• Signal states are safely detected, wire cuts and shortcircuits of signals are safely differentiated.
• Single faults are detected and lead to a safe shut-down.
Principle of function
The input current flowing through the shunt of approx. 200 Ω generates a voltage drop which is transferred to two evaluation channels with identical construction via high-value resistors. The high-resistivity of the resistors guarantees a non-interaction between both channels.

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