Siemens SIMATIC S5-115U, User Manual

Page: 444 / 676

Communications Capabilities S5-115U Manual
Send and Receive Mailboxes
The Send and Receive mailboxes contain send and receive data. They can hold up to 64 bytes of
information. They also contain the following:
•
Length of the data packet (1 to 64 bytes)
• Type of mailbox
- The Send mailbox specifies the destination number.
- The Receive mailbox contains the source number.
Source number
Data packet length Data packet length
Send Mailbox
Destination number
Receive Mailbox
Data
(max. 64 bytes)
Data
(max. 64 bytes)
Byte 1
Byte 2
Byte 3
.
.
.
Byte 66
Figure 12-4. Structure of the Send and Receive Mailboxes
The source or destination number indicates the "device" with which you want to communicate.
Refer to Table 12-2 for the meaning of these numbers.
Table 12-2. Destination and Source Number Assignment
Partner Assignment
0 Master
Slave
Broadcast
1 to 30
31
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
Use the control program to access the mailboxes.
You can assign to the location of the mailboxes.
You can define the starting addresses of the mailboxes in either of the following ways:
•
Specify a data block and a data word.
• Specify a flag word.
Coordination Bytes
Coordination bytes form the interface to the PLC's operating system.
The control programs for the slaves use these bytes to track the flow of local area network traffic
and to influence it.
The following Figures describe the meanings of individual bits.
12-10
EWA 4NEB 811 6130-02b