Analog modules
9.3 SM 336; F-AI 6 x 0/4 ... 20 mA HART
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
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Sensor supply
WARNING
Voltage dips of the power supply are not buffered by the module and, thus, affect the
sensor supply.
This can cause the measured value to be false.
You can avoid voltage dips by using a voltage supply according to the NAMUR
recommendation (see Chapter " Safe Functional Extra-Low Voltage for Fail-Safe Signal
Modules (Page 44) "). Alternatively, use a transducer with an appropriate battery backup or
diagnostics.
Recommendation: Internal sensor supply
You are strongly advised to use the short circuit-proof internal sensor supply of the module.
This internal sensor supply is monitored and its status is indicated by the Fn LED (see Figure
Front view of SM 336; F-AI 6 x 0/4 ... 20 mA HART).
Note
The internal sensor supply of the associated channel is switched off in case of an overload of
the analog input or short circuit to ground or during power-up in the event of short circuit to
L+ to protect the input.
A check is made approximately 1 minute later to determine if the error has gone.
