Structure \ of the Diagnosis Block of the DC551-CS31¶
If a DC551-CS31 module is connected via a CS31 bus, then the field bus master receives diagnosis information by an extended diagnosis block. The following table shows the structure of this diagnosis block:
Byte number  | 
Description | Possible values | 
|---|---|---|
| 1 | Data length (header included) | 18 | 
| 2 | Diagnosis byte | 0 = Communication with DC551-CS31 OK 1 = Communication with DC551-CS31 failed  | 
| 3 | DC551-CS31 diagnosis byte, module number | 0 = DC551 (e.g. error at the integrated 8DI/16DC) 1 = 1st attached S500 I/O module … 7 = 7th attached S500 I/O module  | 
| 4 | DC551-CS31 diagnosis byte, slot | According to the I/O-Bus specification passed on by modules to the fieldbus master  | 
| 5 | DC551-CS31 diagnosis byte, channel | According to the I/O-Bus specification passed on by modules to the fieldbus master  | 
| 6 | DC551-CS31 diagnosis byte, error code | According to the I/O-Bus specification Bit 7 and bit 6, coded error class 0 = E1 1 = E2 2 = E3 3 = E4 Bit 0 to Bit 5, coded error description passed on by modules to the fieldbus master  | 
| 7 | DC551-CS31 diagnosis byte, flags | According to the I/O-Bus specification Bit 7: 1 = coming error Bit 6: 1 = leaving error Bit 5: 1 = Diag reset Bit 2 to Bit 4: reserved Bit 1: 1 = explicit acknowledgement Bit 0: 1 = static error passed on by modules to the fieldbus master Value = 0: static message for other systems, which do not have a coming/leaving evaluation  | 
| 8ff | reserved |