Siemens Simatic S7-300 - Page 174

Digital modules
3.34 Digital IO module SM 327; DI 8/DO 8 x DC 24 V/0.5 A; programmable (6ES7327-1BH00-0AB0)
S7-300 Automation System Module data
3-126 Manual, 08/2006, A5E00105505-04
Readability of outputs
Readability provides a simple form of diagnosis. You can use this to establish whether the
information which is issued to the process ("1" or "0") actually arrives there.
The digital outputs can be read back to the user data area: When Q11.3 is configured as an
output, for example, it can be read back via I11.3. See the figure below
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&KDQQHOQ
&KDQQHOQ
&KDQQHOQ
&KDQQHOQ
&KDQQHOQ
&KDQQHOQ
&KDQQHOQ
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Figure 3-9 Readability of the outputs of SM 327; DI 8/DO 8 x DC 24 V/0.5 A