Digital Modules
4-19
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Technical Specifications of the SM 421; DI 32 x 24 VDC
Programming package
Associated programming
package As of STEP 7 V 2.0
Dimensions and Weight
Dimensions W H D
(in millimeters) 25 290 210
Weight Approx. 600 g
Data for Specific Module
Number of inputs 32
Length of cable
•Unshielded
•Shielded
Max. 600 m
Max. 1000 m
Voltages, Currents, Potentials
Power rated voltage of the
electronics L+ 24 VDC
•Reverse polarity protection Yes
•Power failure buffering None
Number of inputs that can be
triggered simultaneously 32
Isolation
•Between channels and
backplane bus Yes
•Between channels and
power supply of the
electronics
No
•Between the channels No
Permitted potential difference
•Between the different
circuits 75 VDC / 60 VAC
Insulation tested with
•Channels against
backplane bus and load
voltage L+
500 VDC
Current consumption
•From the backplane bus Max. 30 mA
•From supply voltage L+ Max. 30 mA
Power dissipation of the
module Typ. 6 W
Status, Interrupts, Diagnostics
Status display Green LED per
channel
Interrupts None
Diagnostic functions None
Substitute value can be applied No
Sensor Selection Data
Input voltage
•Rated value
•For signal “1”
•For signal “0”
24 VDC
11 V to 30 V
–3 V to 5 V
–30 V to 5 V as of
version 03
Input current
•At signal “1” 6 mA to 8 mA
Input delay
•At “0” to “1”
•At “1” to “0”
1.2 ms to 4.8 ms
1.2 ms to 4.8 ms
Input characteristic curve To IEC 61131; type 2
Connection of two-wire BEROs Possible
•Permitted bias current Max. 2.5 mA