Integral Standard Function Blocks L2-SEND and L2-RECEIVE S5-95U, SINEC L2
5.4 Status Byte
The status byte (STB) is used to control the data transmission using L2-SEND and L2-RECEIVE.
You need to evaluate the status byte in order to monitor the data exchange between the control
processor of the S5-95U and the communications processor of the S5-95U. The status byte
indicates errors and the status of a job and informs you about data management.
Define the location of the status byte in DB1..
Figure 5-3. Structure of the Status Byte
7654 3210
Status byte (STB)
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e.g., flag byte 200
Length byte (LB)*
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e.g., flag byte 201
7654 3210
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Explanations of
the error display:
see Table 5-8
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Job completed
with error
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Job completed
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Job in progress
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Receive viable
(i.e., you can fetch
data with
L2-RECEIVE)
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Indicates for FB L2-RECEIVE the quantity of data in bytes
( 1 to 242) that have been copied to the destination area
(without leading sign)
* With FBs L2-RECEIVE, the flag byte immediately following the
status byte is reserved for the length byte.
It is not available to the user.
!
Warning
If you write in the status byte, undefined states can occur during job processing.
You may only read the status byte.
5-6
EWA 4NEB 812 6112-02