Siemens Simatic RTU303xC Series Operating Instructions Manual page 55

When necessary, actuators can be supplied with voltage via the control outputs X10 or X11
of the RTU.
The digital outputs are designed as bistable relays which maintain their current state even in
sleep mode of the RTU without power supply. In the open status, no current flows by the two
terminals of the individual outputs.
X32 .. X33: Digital outputs (RTU3031C)
The four connectors are intended for the control inputs of actuators or relays. They can also
be used to control an external router.
When necessary, actuators can be supplied with voltage via the control outputs X10 or X11
of the RTU.
The digital outputs are designed as electronic relays and require power even in sleep mode
of the RTU in order to maintain the "closed" state. In the open status, no current flows by the
two terminals of the individual outputs. The electronic relays are preferable to the bistable
relays on X30 .. X31 for fast and frequent switching cycles.
X40 .. X43: Analog inputs
Up to four analog sensors can be connected.
The RTU supports the following output signals:
● Current / voltage (measuring transducer with auxiliary power)
– 0/4 ... 20 mA
– 0 ... 10 V
– 0 ... 5 V
● Temperature, Pt1000 (sensor sensor in 2-wire technology)
-80 ... +140 °C / -112 .. +284 °F
The cable resistances can be specified in the WBM to correct the temperature measured
values. As an alternative, the cable resistances can be calculated on the RTU by
specifying specific table data.
The signal types of the inputs are configured in the WBM of the RTU.
The inputs X41/0 and X41/1 measure at the same time, the inputs X43/0 and X43/1 following
this and one after the other. Refer to the notes in section Analog inputs (Page 184).
The input AI0 can also be monitored for changes in sleep mode.
RTU303xC
Operating Instructions, 06/2019, C79000-G8976-C382-06
LEDs, connectors, buttons, card slots
2.3 Interfaces and connectors
55