Communication program

3.4.2. Communication program

The table below describes the properties of the communication program:

Location Features

Sending station - Precisely 1 connection is configured per receiving station
- The communication program runs in the OB1 cycle
- A complete data block is always sent; i.e. one call per job
- A data block is always used as data source

Receiving station - The communication program runs in the OB1 cycle
- A complete data block is always received
- The received data block is always stored in a data module

Location	Features
Sending station	- Precisely 1 connection is configured per receiving station - The communication program runs in the OB1 cycle - A complete data block is always sent; i.e. one call per job - A data block is always used as data source
Receiving station	- The communication program runs in the OB1 cycle - A complete data block is always received - The received data block is always stored in a data module

Note:

The above properties have the following consequences
- The maximum number of receiving stations is limited by the number of connection resources and communication service (e.g. CP 343-1 lean: 8)
- The maximum length of the data block is the maximum length of the communication block and the communication service possible (e.g. for TSEND: 1452Bytes for S7-300)