
User Manual
Z-KEY-P
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Doc: MI00572-1-EN
Page 51
MODBUS DIAGNOSTICS
10.
The diagnostics management takes the timeout or exceptions to the Modbus requests of the tags into account.
Z-KEY-P will introduce the OK status (0x35) or the FAIL status (0x15) in the “data status” field of the Profinet
packets if at least one tag is in FAIL status.
There are also specific Bytes to obtain the status of the Modbus communication from Profinet so that the PLC
can possibly perform some specific operations in case of fail.
If at least one ModBUS tag is in fail the "Global diagnostic" byte goes to 1, if all the tags are read correctly the
byte goes to 0.
It is also possible to obtain the status of the individual tags using the "8 tags Diagnostic read byte" bytes.
Each bit represents the status of a tag, where the first byte represents the first 8 tags, the second the other 8
etc.
If the bit is:
0 -> TAG OK
1 -> TAG FAIL
Having a maximum of 20 Slots available, it is not possible to obtain the diagnostics of each single tag on all
500.