Siemens SIMATIC S7-400 Reference Manual page 125

● For "1" to "0"
Input characteristic
Connection of 2-wire BEROs
● Permissible quiescent current
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08
4.12 Digital input module SM 421; DI 16 x UC 120/230 V (6ES7421-1FH20-0AA0)
Maximum 30 ms AC
Maximum 25 ms DC
In accordance with IEC 61131-2; type 2
Possible
Maximum 5 mA AC
Digital modules
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