Communication Blocks Xcom (Cpu300); Fb Xcom; Db Xcomdata - Siemens TIM 1531 IRC Operating Instructions Manual

It also contains central data required to control and manage the connection that runs via this
mailbox.
The data block is required in every CPU in which FB PCom is used. If the CPU has several
corresponding connections the DB is required more than once.
5.7.7

Communication blocks XCom (CPU300)

5.7.7.1

FB XCom

Validity
S7-300 CPU with partyline
Function
Auxiliary block for FC BasicTask_X for processing a communication mailbox of the type DB
XComData.
Via DB BComData a configured connection (PBK connection) is handled using the SFCs
"X_SEND" und "X_RCV".
The FB XCom also ensures that received frames are distributed immediately to the receiving
objects responsible in the CPU. To do this the FB XCom calls the FC Distribute as an
auxiliary block.
5.7.7.2

DB XComData

Instance data block for the communication block FB XCom. The instance DB makes the
communication mailbox available and contains the following:
● The receive mailbox (ReceiveBuffer)
● A send mailbox (SendBuffer)
It also contains central data required to control and manage the X connection that runs via
this mailbox.
The data block is required in every CPU in which FB XCom is used. If the CPU has several
X connections the DB is required more than once.
DB XComData is automatically generated in the required length preset with the connection
specific data and then saved in the block directory of the CPU.
TIM 1531 IRC
Operating Instructions, 02/2018, C79000-G8976-C468-02
Block library TeleControl ST7
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