Siemens Simatic S7-400 - Manual (Page 145)

Digital Modules
4-23
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
4.9 Digital Input Module SM 421; DI 16 24 VDC;
(6ES7421-7BH00-0AB0)
Characteristics
The digital input module SM 421; DI 16 24 VDC has the following features:
• 16 inputs, isolated in 2 groups of 8
• 24 VDC rated input voltage
• Suitable for switches and two/three/four-wire proximity switches
(BEROs, IEC 61131; type 2)
• 2 short-circuit-proof sensor supplies for 8 channels each
• External redundant power supply possible to supply sensors
• “Sensor supply (Vs) O.K.” status display
• Group error display for internal faults (INTF) and external faults (EXTF)
• Programmable diagnostics
• Programmable diagnostic interrupt
• Programmable hardware interrupt
• Programmable input delays
• Parameterizable substitute values in the input range
The status LEDs indicate the process status.