Siemens SIMATIC SM 335 Manual page 53

Response with CPU-STOP
When the CPU is at STOP or executing the startup routine, the SM 335 outputs
the substitute value to the relevant analog output until a new value is specified.
The SM 335 uses the following as a substitute value:
• 0 V
(if "Outputs off circuit and de-energized" has been set in HW Config) or
• the analog value last output
(if "Retain last value" has been set in HW Config).
SM 335 – High-Speed Analog Input/Output Module for the SIMATIC S7-300
6ES7 335-7HG00-8BA1
Data Exchange with the SM 335
3-15