Siemens SIMATIC S5 CP 523 Manual page 191

CP 523
8 Using the "SEND" and "RECEIVE" Function
Blocks
The "SEND" and "RECEIVE" function blocks, FB 200 and FB 201, offer you a user-friendly interface
which considerably simplifies use of "Send message frame to peripheral device" job (A001
"Receive message frame from peripheral device" (A080
message frame immediately by calling FB 200 or FB 201 instead of having to program the send or
receive program yourself.
To transfer messages frames, you need only assign the relevant FB parameters. The next two
sections (8.1 and 8.1.1) describe FB parameter setting. Transfer of a message frame is initiated by
calling FB 200 or FB 201. The FBs have a status byte containing information on the CP, the
peripheral device and data transfer.
Note :
These FBs can execute on CPU 941 to CPU 944. They can also execute in the 135U, 150U and
155U if network 3 is omitted (or "reprogrammed" for other PLCs). Normally, network 3 can be
omitted when sufficient space is provided in the source and destination DBs.
8.1 Using "SEND" FB 200
"SEND" FB 200 transfers a message frame of fixed or variable length from the CPU to the peri-
pheral device. You must store the message frame to be transferred in a data block (source data
block) before calling "SEND" FB 200. When you invoke the "SEND" FB 200, you must specify the
following:
• The start address of the CP 523
• The number of the source data block from which the message frame is to be transferred to the
CP 523
• The number of the source data word beginning in which the message frame is stored.
• The length of the message frame to be transferred (number of source data words) or of two
end-of-text characters
• A byte address where "SEND" FB 200 is to store the status byte.
• A byte address where "SEND" FB 200 is to store the coordination byte for send (CBS) (3964(R)
only).
• Specification as to whether with or without computer-computer link.
Send is initiated when the RLO is 1 when FB 200 is invoked.
EWA 4NEB 811 6044-02a
Using the "SEND" and "Receive" Function Blocks
). You can initiate the transfer of a
H
) and
H
8-1