Siemens Simatic M7-400 Reference Manual page 139

4.7 Digital Input Module SM 421; DI 32
(6ES7421-1BL00-0AA0)
Characteristics
The SM 421;DI 32 x 24 VDC is a digital input module with the following features:
• 32 inputs, isolated in a group of 32. In other words, all inputs share the same
chassis ground.
• Rated load voltage: 24 VDC
• Suitable for switches and 2-wire proximity switches
(BEROs, IEC 61131; type 2).
The status LEDs indicate the process status.
Functional Expansion as of Version 03
The lower limit of the rated input range is increased at signal "0" from –3 to –30 V.
The rated input voltage for signal "0" is thus: –30 V to 5 V
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Digital Modules
24 VDC
4-17