Siemens SIMATIC ET 200iSP Operating Instructions Manual page 166

Commissioning and Diagnostics
6.8 Diagnostics with STEP 7
For each channel-related diagnostic information, 3 bytes are added as per
Ed1 CP 3/1 .
The channel-related diagnostic information follows the module status.
Channel-related diagnostics does not affect the module status.
Important: The group diagnostics must be switched on for each module.
Channel-related diagnostics
The maximum number of channel-related diagnostics is restricted by the maximum overall
length of the slave diagnostics of 96 bytes with IM 152. The length of the slave diagnostics
depends on the number of the currently existing channel-related diagnostics. If there are more
channel-related diagnostics present than the slave diagnostics can show, bit 7 is set to
"Diagnostics Overflow" in the station status 3.
166
IEC 61784-1:2002
Operating Instructions, 11/2017, A5E00247483-07
ET 200iSP