Digital Modules
4-22 S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Technical Specifications of the SM 421; DI 32 x 24 VDC
Dimensions and Weight
Dimensions W H D
(in millimeters) 25 290 210
Weight Approx. 500 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+ Not required
Number of inputs that can be
triggered simultaneously 32
Isolation
Between channels and
backplane bus Yes
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. 20 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
Data for Selecting a Sensor
Input voltage
Rated value
For signal “1”
For signal “0”
24 VDC
13 V to 30 V
-30 V to 5 V
Input current
At signal “1” 7 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 1
Connection of two-wire BEROs Possible
Permitted bias current Max. 1.5 mA