Siemens Simatic S7-400 - Manual (Page 200)

Digital Modules
4-78
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
4.20.2 Behavior of the SM 422; DO 32 24 VDC/0.5 A
Effect of Operating Mode and Supply Voltage on the Output Values
The output values of the SM 422; DO 32 24 VDC/0.5 A depend on the
operating mode of the CPU and on the supply voltage of the module.
Table 4-19 Dependence of the Output Values on the Operating Mode of the CPU and on
the Supply Voltage L+ of the SM 422; DO 32 24 VDC/0.5 A
CPU Operating Mode Power Supply L+
to Digital Module Output Value of Digital
Module
POWER ON RUN L+ exists CPU value
L+ missing 0 signal
STOP L+ exists Substitute value/last value (0
signal preset)
L+ missing 0 signal
POWER
OFF – L+ exists 0 signal
OFF
L+ missing 0 signal
Behavior in the Event of Failure of the Supply Voltage
The failure of the supply voltage of the SM 422; DO 32 24VDC/0.5 A is always
indicated by the EXTF LED on the module. Furthermore, this information is made
available on the module (entry in diagnosis).
Triggering of the diagnostic interrupt depends on the parameter assignment (see
Section 4.20.1).