Specifications

SINEC L1-Data Handling Software for S5 115U Section 4-5

4.5.2 Interface to the Application Software

The interface to the PLC application software is not of a very complex design. This

is due to the fact that the supplied function blocks handle the entire data exchange

process with the operating terminal via the send mail box and receive mail box. The

function blocks merely need to be executed as described above.

The function blocks also control every access, read-access as well as write-ac-

cess, to data in the PLC. Again, there is no need for an application software for this

process.

The only task remaining for the application software is the transfer of the status

data area. For this process, an area comprising 6 words (DW70 to DW75) has been

reserved in the communications data block L1DB. This area allows the PLC to

inﬂuence the terminal.

The entire area will be transferred to the terminal whenever the value 1 is written

into DL69. After the transmission has been completed, the supplied function blocks

will reset DL69 to 0. Thus DL69 represents a coordination byte which is used to

control the points of time at which the status data area is to be transferred or in-

dicates whether the transfer has already been effected.

The coordination byte can also be used by the application software for the function

communication monitoring. This is possible since the coordination byte is reset to 0

after a speciﬁed period of time only if the PLC is still connected to the operating

terminal. The timeout period should logically be greater than 1 second.

All other data of the L1DB, with the exception of the data mentioned above, may not

be accessed by the application software.

4.5.3 Initialization Function Block FB200

The process of executing FB200 through the start-up blocks OB21 and OB22 must

be carried out only once. Prior to this, however, the communications data block

L1DB must have been created since access to certain words of this data block is

required for the execution process.

This function block initializes the system data area of the PLC using SINEC L1

communication parameters.

The following values are entered for the parameters:

PU-number: not relevant here

Slave-number: as speciﬁed during programming of the terminal

KBE: DW1 in L1DB

KBS: DW0 in L1DB

Receive mail box: DW36 to DW68 in L1DB

Send mail box: DW2 to DW34 in L1DB

In addition, FB200 performs the required initialization processes in L1DB.

The only parameter to be deﬁned for FB200 is the number of the communications

data block L1DB.