Application: Connecting 2 Loads In Parallel Per Digital Output, Pm-Switching Mode - Siemens SIMATIC S7-1500 Manual

5.4 Application: Connecting 2 loads in parallel per digital output,
PM-switching mode
To protect against cross-circuits between P-switch and M-switch in fail-safe digital outputs,
we recommend the following wiring scheme. This circuit achieves SIL3/Cat.4/PLe.
The figure below shows an example of the pin assignment of the fail-safe digital output
module F-DQ 8x24VDC/2A PPM with connection of two parallel loads per digital output,
PM-switching mode.
To protect the F-module, always install an external fuse with the following properties for the
load circuit: Circuit-breaker 24 V DC/16 A, tripping characteristic type B.
①
Backplane bus interface
②
Microcontroller 1
③
P1 switch for channel groups 0 to 3
Image 5-3 Wiring diagram for 2 relays in parallel to 1 F-DQ of the digital output module F-DQ 8x24VDC/2A PPM,
PM-switching mode
Digital output module F-DQ 8x24VDC/2A PPM (6ES7526-2BF00-0AB0)
Manual, 01/2016, A5E03858037-AA

5.4 Application: Connecting 2 loads in parallel per digital output, PM-switching mode

WARNING
④
Microcontroller 2
⑤
P1 switch for channel groups 4 to 7
⑥
Reverse polarity protection
Applications of the F-I/O module
37