
Digital modules
4.8 Digital input module SM 421; DI 16 x DC 24 V (6ES7421-7BH01-0AB0)
S7-400 Automation System Module Data
118 Reference Manual, Edition 09/2009, A5E00850736-06
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 Relationships between the input values of errors and the configuration
Diagnostic message "Diagnostics"
parameter
"Reaction to Error"
parameter
Input value of digital module
No module
parameters
Cannot be
disabled
Not relevant 0 signal (all channels)
Substitute a value
(SV)
Configured substitute value Front connector
missing
KLV Last read, valid value
Incorrect parameters
(module/channel)
Cannot be
disabled
Not relevant 0 signal (module/all incorrectly
configured channels)
Substitute a value
(SV)
Configured substitute value Internal voltage failure Cannot be
disabled
KLV Last read, valid value
Hardware interrupt
lost
Cannot be
disabled
Not relevant Current process value
Disabled - 0 signal
Substitute a value
(SV)
Configured substitute value
Wire break (for each
channel)
Activated
KLV Last read, valid value
Disabled - 0 signal
Substitute a value
(SV)
Configured substitute value
Sensor supply
missing (also
activated via "No
Load Voltage L+")
Activated
KLV Last read, valid value
Disabled - 0 signal, if the contact is connected via
the sensor supply; process value for
the external sensor supply
Substitute a value
(SV)
Configured substitute value
No load voltage L+
(for each channel
group)
Activated
KLV Last read, valid value
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