Specifications

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

4.5.4 Communications Function Block FB201

FB201 must be executed by OB1 at cyclic intervals. The handling of the data ex-

change with the operating terminal is performed entirely by this function block. This

process involves that the FB, each time it is being executed, veriﬁes whether a read

or write request has been received from the terminal and carries out such a re-

quest, if necessary. To carry out a read or write request, it will execute FB202 or

FB203, respectively, which are responsible for reading or writing to variables, re-

spectively.

In the event that the terminal has not sent a request, the FB will check whether the

status data area is to be transferred to the terminal and will, if necessary, carry out

this process.

The only parameter to be deﬁned for FB201 is the number of the communications

data block L1DB.

4.6 SINEC L1 Data Handling Software for S5 135U with CP530

4.6.1 Installation

The interfacing of the operating terminals to the Simatic S5 135U via the CPU 530

requires the installation of the supplied data handling software into the PLC. To

install the software, carry out the following steps:

- The four supplied function blocks FB200, FB201, FB202 and FB203 must be

installed.

- A data block (L1DB) must be created in the RAM of the PLC. The minimum size

required for this data block is 93 data words. The data block can either be cre-

ated with the aid of the programming unit or through the start-up OBs. This

process must be carried out before one of the function blocks mentioned above

is executed for the ﬁrst time. The block must be assigned the number 15, since

this is the number that is being used for the parameterization of the SEND and

RECEIVE data handling block FB201. In the event that DB-number 15 has al-

ready been used elsewhere, another option is to alter the DBNR parameter

when executing the data handling blocks in FB 201.

- FB200 must be executed through start-up blocks OB20, OB21 and OB22. FB

200 will handle the synchronization with the CP530 and also carry out the re-

quired initialization of the data in L1DB.

- FB201 must be executed through OB1. FB 201 controls the data exchange with

the operating terminal. When necessary, it will execute FBs 202 or 203 for this

process. These two function blocks may not be executed directly by the applica-

tion software.

The function blocks use ﬂag words FW248 to FW254 as scratch ﬂags. This means

that if you wish to retain this information, it is necessary to transfer the contents of

these ﬂag words before the communications function blocks are executed.