5
2121341-06-11/20 (Translation of the original operating instructions)
Operating Instructions MODULAR SAFETY CONTROL SYSTEM MSC
MSC FIELDBUS MODULES CE-...
EN
4. Layout of the protocol data packet
The fieldbus module transmits the system status as well as the status and diagnostic elements for all inputs/outputs that
are configured in the MSC system, and makes it possible to read up to 32 separate fieldbus inputs.
The input and output structures are described in chapters 4.1 and 4.2.
The input structure consists of up to four bytes that represent the fieldbus inputs. The number of input bytes depends on
the firmware version of the fieldbus module, see Table 2.
Fieldbus module firmware version
Size of input structure
< 2.0
1 byte (8 fieldbus inputs)
≥ 2.0
4 byte (32 fieldbus inputs)
Table 2: Fieldbus input structure
FW ≥ 2.0
The base unit MSC-CB can process only 8 fieldbus inputs, which is why only the first byte in the input
structure is used.
FW < 2.0
The base unit MSC-CB-S can process up to 32 fieldbus inputs, but only the first byte is transferred due
to the limitation of the input structure.
FW ≥ 2.0
The output structure comprises:
Ì
one status byte,
Ì
one reserved byte,
Ì
16 bytes for the status of the inputs,
Ì
4 bytes for the feedback of the fieldbus inputs,
Ì
4 bytes for the status of the fieldbus outputs,
Ì
4 bytes for the status of the safe outputs,
Ì
64 bytes reserved for analog data that are not available in the current EUCHNER portfolio,
Ì
64 bytes for diagnoses
FW < 2.0
The output structure comprises:
Ì
one status byte,
Ì
a variable number of bytes for the status of the inputs (max. 16 bytes),
Ì
one byte for the feedback of the fieldbus inputs,
Ì
two bytes for the status of the fieldbus outputs,
Ì
a variable number of bytes for the status of the safe outputs (max. 2 bytes),
Ì
two bytes for diagnoses
The system status is indicated by one byte:
Ì
Bit 0 indicates whether the MSC system is online or offline
Ì
Bit 1 indicates whether diagnostic information is available
Ì
Bit 2 indicates whether there is an error in the MSC system (only firmware version ≥ 2.0)
Each input and each output (OSSD) that is configured in the MSC system is linked to two information elements: Status and
Diagnostics.
Status is a binary value, 0 or 1, Diagnostics is a code for the indication of the IO state, which can be in correct working
order, or which can be indicative of a problem on the I/O.
Each module with inputs has a number of bits that corresponds to the number of inputs present. For this reason, the modules
MSC-CB, MSC-CB-S, FI8, FI8FO2 and FI8FO4S are linked to one byte (8 bits) and the modules FI16 and FM4 to two bytes
(16 bits) for the input status.
Depending on the type of the respectively installed modules, the position of the inputs varies in the following sequence: MSC-
CB/MSC-CB-S, FI8FO2, FI16, FI8, FM4, SPM2, SPM1, SPM0, FI8FO4S. If several modules of the same type are installed,
the order corresponds to the node number.
