Siemens SIMATIC S7-1500 Manual page 21

Status information
The following image shows the assignment and meaning of the status bytes.
Status byte 0 provides information regarding the validity of the processed data. If the
processed data is invalid, status byte 1 provides additional information on the cause.
Assignment of the status bytes in the PII
Figure 5-3
Bit 3 in status byte 1 signals errors in the Ethernet configuration. For more on this, read
section Diagnostics alarms (Page 23)
Control information
The control bytes 0 and 1 are reserved for a later version of the module.
Assignment of the control bytes in the PIQ
Figure 5-4
Technology Module TM NPU
Equipment Manual, 09/2020, A5E46384784-AA
Status bytes in the PII
Control bytes in the PIQ
Configuration / address space
5.2 Address space and address assignment
19