9 Appendix
9.1 Data image of the technology modules
XI/ON: XNE-GWBR-2ETH-MB
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9.1.4
SSI-module
Process input data
The field input data is transferred from the connected field device to the XN-1SSI module.
The process input data is the data that is transferred to the PLC from the XN-1SSI via a
gateway.
This is transferred in an 8 byte format as follows:
• 4 bytes are used for representing the data that was read from the register with the address
stated at REG_RD_ADR.
• When necessary, 1 byte represents the register address of the read data and an acknow-
ledgement that the read operation was successful.
• 1 byte can be used to transfer status messages of the SSI encoder. This byte also contains
an acknowledgement that the write operation to the register was successful and indication
of an active write operation.
• 1 byte contains the results of comparison operations with the SSI encoder value.
• 1 byte contains messages concerning the communication status between the XN-1SSI
module and the SSI encoder, as well as other results of comparison operations.
The following table describes the structure of the 8 x 8 bits of the process input data.
STS (or ERR) contains non-retentive status information, i.e. the bit concerned indicates the
actual status.
FLAG describes a retentive flag that is set in the event of a particular event. The bit concerned
retains the value until it is reset.
Figure 84:
Process input
data