Siemens SIMATIC Manual page 237

3.39 Programmable digital IO module SM 327; DI 8/DO 8 x DC 24 V/0.5 A (6ES7327-1BH00-0AB0)
Readback of outputs
The readback function is a simple form of diagnostics. You can use this to determine
whether the information output 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 at I11.3. See the figure below
Figure 3-11
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ
Readback of the outputs of SM 327; DI 8/DO 8 x DC 24 V/0.5 A
Digital modules
237