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Quantum safety architectures - Modicon Quantum Automation Platform Page 6-30

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Diagnostics of the safety discrete output module 140SDO95300S

The diagram below illustrates the internal architecture of the Quantum safety discrete output module 140SDO95300S . Safety function Module 140SDO95300S is a discrete output module and its safety function is to ensure: That the CPU control is actually applied to the output: b If communication between the module and the CPU is regular and correct b If the internal diagnostics confirm that the module is correctly integrated In contrast, as soon as the internal diagnostics reveal the failure of a part of the system, the module is designed to ensure the channel switches safely to the fallback position, i.e. to apply a 0 command, zero voltage, the only one that can be fuaranteed. Internal diagnostics Diagnostics




are identical to those of the discrete input module 140SDI95300S (see page 6/29). Like all safety modules and CPUs, the 140SDO95300S module is internally fully redundant. The output is controlled by two different control devices. Each is controlled by a microprocessor. The output stage is checked. Schematically, each output consists of two switches in series. The mid-point voltage


is assessed, and this data item is sent separately to each microprocessor. As there is only one situation where at point


the voltage can be floating point, both switches open, the mechanism checks with certainty the possibility of opening both switches, to create the safety function. Thus: When the current PLC command is 0, the module checks from time to time whether it is capable of controlling both switches in all possible combinations, except for a command at 1. When the current PLC command is 1, all combinations are tested. The output changes to 0 briefly, for < 1 ms. This has no effect in industrial control where the controlled devices are motors or valves that are insensitive to disturbances in control lasting this long. The diagram also shows the connection of the external 24 V c power supply, designed to ensure detection of any failure of the supply.

6 2 4 5 3 24 V Separation Actuator Output Value 2 Separation Value 1 Functional link Diagnostics Diagnostics and comparison Separation/ vote Proc 2 Proc 1


Actuator COM Control 1 COM to process power supply Control 2

Modicon Quantum automation platform

Safety I/O modules



CPUs: page 1/2 I/O architectures: page 2/6 I/O: page 3/2 Communication: page 5/2

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