Siemens SIMATIC S5 CP 523 Manual page 188

CP 523
Example: Receiving a 12-byte message frame with 3964(R) protocol
Base address 128 is set on the CP. The message frame is to be stored in data block 21 beginning
DW 0. Flag 101.0 is to be set as soon as a message frame is entered in data block 21. The statement
list does not explain how or when flag 101.0 is reset. This can be done, for example, when the
message frame has been evaluated and data block 21 can be overwritten.
STL FB 127
NAME :RECEIVE2
:A F 101.0
:BEC
:L KH A080
:T PW 128*
:L PY 129
:T FY 111
:L KH 0080
:L PW 128
:AW
:><F
:BEC
:S F 101.0
:C DB 21
:L KH
:T PW 128*
:L PW 134
:T DW 3
:L PW 132
:T DW 2
:L PW 130
:T DW 1
:L PW 128
:T DW 0
:L KH 0000
:T PW 128*
:L PW 130
:T DW 5
:L PW 128
:T DW 4
:BE
* 5.2
EWA 4NEB 811 6044-02a
Flag 101.0 is set when a message frame has been entered in DB 21,
then Block End conditional
Load "Receive message frame" request into ACCUM 1
Transfer to word 0 in transfer memory
Load CBR into flag byte 111 (for error
analysis if necessary)
Check to see if Receive mailbox is empty
Read and analyze coordination info
When Receive mailbox is empty,
then Block End conditional.
If it is not, set flag 101.0 and
open DB 21.
0000
Read transfer memory word 6 and
transfer to DW 3
Read transfer memory word 4 and
transfer to DW 2
Read transfer memory word 2 and
transfer to DW 1
Read transfer memory word 0 and
transfer to DW 0
Write to transfer memory word 0
Read transfer memory word 2 and
transfer to DW 5
Read transfer memory word 0 and
transfer to DW 4
Communications Mode
Explanation
7-83