Siemens SIMATIC S7-1500 Manual page 56

Digital outputs at the X142 interface
You configure each of the digital outputs as sourcing output or as high-speed output:
● Sourcing output: The digital output is a 24 V sourcing output in reference to M and can
carry a rated load current of 0.5 A.
● High-speed output: The digital output is a high-speed push-pull switch and can carry a
rated load current of 0.4 A. A push-pull switch is alternately switched to 24 V DC and
ground. Very steep edges are possible as a result.
The digital outputs are protected against overload and short-circuit.
The direct connection of relays and contactors is possible without external wiring.
NOTICE
Overheating of unsuitable loads
A high-speed output generates edges that are very steep. This generates very powerful
charge reversals for the connected load, which can overheat the load at very high switching
frequencies. The connected load must therefore be suited for high input frequencies.
Note
If you use a digital output as a sourcing output, its switch-off response/switch-off edge is
dependent on the connected load. Thus it is possible that very short pulses cannot be output
correctly.
Note
For optimal interference immunity and high-accuracy signal acquisition, we recommend the
use of shielded cables in the following cases:
• Very brief signal levels or very fast signal changes occur at the digital inputs, e.g. when
used as timer DI/measurement sensing input, as oversampling DI or for event/period
duration measurement
• An input delay of 1 μs is set for X142
SIMATIC Drive Controller
Equipment Manual, 11/2019, A5E46600370-AA
3.4 Digital inputs and outputs of X122, X132 and X142
Connecting
55