Technical data

S7 Communication
System Software for S7-300/400 System and Standard Functions - Volume 2/2
21-2 A5E00739858-01
Addressing Parameters
Parameter Description
ID Reference to the local connection description (specified by the STEP 7 configuration of the
connection).
R_ID Use the R_ID parameter to specify that a send and a receive SFB belong together: The
R_ID parameter must be identical at the SFB/FB on the send end and at the SFB on the
receive end.
This allows the communication of several SFB/FB pairs via the same logic connection.
• R_ID must be specified in the form DW#16#wxyzWXYZ.
• The block pairs of a logic connection which are specified in R_ID must be unique for
this connection.
The parameter PI_NAME is only described at the relevant SFBs (S7-400 only).
Note
S7-300: You can change the parameters in the addressing parameters ID and R ID
while they are active. The new parameters are validated with each new job after
the previous job has been closed. Here, you can link multiple FB pairs in one
instance.
Tip: You have the following possibilities to save instance DBs and therefore
working memory:
1. With variable IDs you can use several connections via one data instance block.
2. With variable R_IDs you can define several identities of pairs of send and
receive FBs for one job.
3. You can combine case 1 and case 2.
4. Please observe that the new parameters are valid after the last job is
executed. If you activate the send job, the R_ID parameter of the sending and
the receiving FB must match.
S7-400: The addressing parameters ID and R ID are evaluated only at the first call
of the block (the actual parameters or the predefined values from the instance).
The first call therefore specifies the communication relation (connection) with the
remote partner until the next warm or cold restart.
Status Parameters
With the status parameters, you monitor whether the block has completed its task
correctly or whether it is still active. The status parameters also indicate errors.
Note
The status parameters are valid for one cycle only, namely from the first instruction
which follows the SFB/FB call until the next SFB/FB call. As a result, you must
evaluate these parameters after each block cycle.