Communication Using Function Blocks
6-5
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
6.4
Using the Function Blocks
The following sections describe what you must take into account when supplying
the function blocks with parameters.
STATUS Display on the FB
Please note the following with reference to the STATUS display on the function
blocks:
Note
The DONE, NDR, LEN, ERROR and STATUS parameters are set for only one
block run. To display the STATUS, you should therefore copy it to a free data area.
If the job runs through with DONE =’1’, the job was executed without errors.
This means:
•
Using the ASCII driver: The job was sent to the communication partner. It is not
certain that the data was also received by the communication partner.
•
Using the 3964(R) procedure: The job was sent to the communication partner
and acknowledged affirmatively by the communication partner. It is not certain
that the data was also transferred to the partner CPU.
Simultaneously Processed Jobs
Only one SEND_440 FB, one RECV_440 FB and one RES_RECV FB can be
programmed in the user program for each CP 440 used.
In addition, you can only use the following data blocks because the states required
for the internal execution of the FB are stored in the instance data block:
•
1 instance data block for the SEND_440 FB
•
1 instance data block for the RECV_440 FB
•
1 instance data block for the RES_RECV FB
