Application examples
9.1 Input/output interconnections for a safety switching device with TM54F
Safety Integrated
242 Function Manual, 05/2010, A5E03264275A
TM54F: Interconnecting F-DI with a plus-minus switching output on a safety switching device
WARNING
In contrast to mechanical switching contacts (e.g. Emergency Stop switches), leakage
currents can still flow in semiconductor switches such as those usually used at digital
outputs even when they have been switched off. This can lead to false switching states if
digital inputs are not connected correctly.
The conditions for digital inputs/outputs specified in the relevant manufacturer
documentation must be observed.
WARNING
In accordance with IEC 61131 Part 2, Chapter 5.2, when interconnecting the digital inputs
of the TM54F with digital semiconductor outputs, only outputs that have a maximum
residual current of 0.5 mA when in the "OFF" state can be used.
Debounce
Test signals from the controls can be filtered out using parameter p10017 (SI digital inputs,
debounce time) so that faults are not misinterpreted.
F-DI = safety-oriented dual-channel digital input
F-DO = safety-oriented dual-channel digital output
If digital outputs from another device (e.g. F-DOs on a safety PLC) with a residual current
greater than 0.5 mA in the "OFF" state are connected to the F-DIs of the TM54F, then F-DI
load resistors should be connected up in the channel involved.
The maximum permissible voltage for a TM54F F-DI when "OFF" is 5 V (in accordance with
IEC 61131-2).
The following two diagrams show exactly how the protective circuits for F-DIs with additional
load resistors are wired.
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