Connecting
3.1 Wiring and block diagram
Analog input module F-AI 4xI 0(4)..20mA 2-/4-wire HF (6ES7136-6AA00-0CA1)
18
Manual, 08/2018, A5E41448857-AB
Recommendation: Internal sensor supply
You are strongly advised to use the short circuit-proof internal sensor supply of the F-
module. This internal sensor supply is monitored and its status is indicated by the Fn LED.
The input is also protected in the event of short-circuits in the wiring or at the sensor.
Note
The internal sensor supply is switched off in case of a short circuit to ground or during
power-up in the event of short circuit to L+.
The sensor supply is also switched off at input currents > 35 mA.
A check is made approximately 1 minute later to determine if the error has gone.
Note
Behavior of process values and diagnostics evaluation
Sensor startup during module startup:
After the internal sensor supply is activated, the evaluation of wire break and underflow
diagnostics is suppressed for 3 seconds. During this time, the module makes the secure
process data 0 available at all channels. This suppresses a possible wire break or underflow
diagnostics caused by the sensor startup. If the sensor startup is not yet complete after the 3
seconds have elapsed, it is possible that the module might detect wire break or underflow
and passivate the affected channel. In this case, the channel fault must be acknowledged
during startup.
Sensor startup during operation:
If a sensor startup takes place during operation, e.g. the sensor supply is reactivated after a
short-circuit, all analog values are invalid and wire break or underflow diagnostics can occur
on the sensors connected to the internal sensor supply.
