Siemens Automation System S7-400 - Manual (Page 72)

Wiring the S7-400
4-12
Automation System S7-400 Hardware and Installation
A5E00850741-01
4.8 Parallel Wiring of Digital S7-400 Outputs
Parallel Wiring of a Digital Output with Different Rated Load Voltages
The parallel wiring of a digital output (rated load voltage 1L+) with another digital
output (rated load voltage 2L+) or a rated load voltage 3L+ is only possible using
series diodes.
1 L+ 2 L+ 3 L+
Figure 4-5 Parallel Wiring of a Digital Output with Different Rated Load Voltages
Parallel Wiring of a Digital Output with Identical Rated Load Voltages
If the L+ supplies of the digital output modules and the L+ voltage connected in
parallel to the output are always the same (difference < 0.5 V), there is no need to
use diodes, see figure 4-6.
L+
Figure 4-6 Parallel Wiring of a Digital Output with Identical Rated Load Voltages