Behavior Of The Sm 421; Di 16 X Dc 24 V - Siemens SIMATIC S7-400 Reference Manual

4.8.3

Behavior of the SM 421; DI 16 x DC 24 V

Effect of operating mode and supply voltage on the input values
The input values of the SM 421; DI 16 x 24 DC depend on the operating mode of the CPU and
on the supply voltage of the module.
Table 4-9
CPU operating state
POWER ON
POWER OFF
* Depends on the parameter assignment
Reaction to failure of the supply voltage
Failure of the supply voltage of the SM 421; DI 16 x 24 DC is always indicated by the EXTF
LED on the module. This information is also available on the module (entry in diagnostic data.)
Diagnostics interrupt triggering is based on parameter settings.
Short-circuit at the sensor supply Vs
The relevant Vs LED goes dark if a short-circuit is detected at the sensor supply Vs, irrespective
of parameter settings.
Effect of errors and parameter assignment on the input values
The input values of the SM 421; DI 16 x 24 DC are affected by certain errors and the parameter
assignment of the module. The following table lists the effects on the input values.
You can find more diagnostic messages in the Appendix "Diagnostic Data of the Signal
Modules".
Table 4-10
Diagnostic message
No module parame‐
ters
Front connector miss‐
ing
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08
4.8 Digital input module SM 421; DI 16 x DC 24 V (6ES7421-7BH01-0AB0)
Relationships of the analog input values on the CPU's operating state and on the L+ supply
voltage
Power supply L+ at digital module
RUN L+ present
L+ missing
STOP L+ present
L+ missing
- L+ present
L+ missing
Relationships between the input values of errors and the configuration
"Diagnostics"
parameter
Cannot be disa‐
bled
Process value
0 signal*
Process value
0 signal*
-
-
"Reaction to Error"
parameter
Not relevant 0 signal (all channels)
Substitute a value Configured substitute value
(SV)
KLV Last read, valid value
Digital modules
Input value of digital module
Input value of digital module
107