Application examples
9.2 Application examples
Safety Integrated
244 Function Manual, 05/2010, A5E03264275A
Dimensioning the load resistors - example 2:
If additional conditions for the digital output (e.g. a minimum load or a maximum load
resistance) are specified in the manufacturer's documentation, then these must be taken into
account.
For example, a load between 12 Ω and 1 kΩ is specified for the SIMATIC ET200S I/O
module 4 F-DO (6ES7138-4FB02-0AB0).
Therefore, two additional load resistors with a continuous load capacity of at least P =
(28.8 V)²/R = 830 mW are required to connect an F-DO of this kind to a TM54F F-DI.
If a controlled 24 V power supply is used (e.g. SITOP), a resistor with a significantly lower
power loss is sufficient.
Note
Open-circuit detection for a pull-up resistor
If the pull-up resistor is higher than 1 kΩ, then the open-circuit detection no longer reliably
functions and must be disabled.
9.2 Application examples
Application examples can be found at the following Siemens website:
http://support.automation.siemens.com/WW/view/en/20810941/136000t
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