CONTROLINK86 SMSC, CONTROLINK86 Datasheet - Page 27

• Manufacturer Part Number: CONTROLINK86
• Description: Development Software Embedded Networking Software
• Manufacturer: SMSC

Specifications of CONTROLINK86

• Tool Function: Compiler
• Tool Type: Compiler
• Processor Series: 80x86
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ControLink86 Realtime Networking Software
3.6.2SERVICE ACCESS POINT (SAP) SERVICES
The SAP services are directed at the local service access points (at the stations Logical Link Layer). The
activation and deactivation requests are used to start/stop a SAP. The XID and TEST requests are used
to exchange information about the types of services and test the communications link. The DATA request
is the main messaging service of the LLC.
3.6.2.1SAP ACTIVATION/DEACTIVATION
The local SAPs are activated or deactivated by providing the lssap (local source SAP) value and a local
SAP structure. Each SAP within a node should have an LLC structure as described in Section 3.4
associated with it. The LLC_MSG structure member msgptr must be initialized to a valid buffer in order
for that SAP to send or receive messages.
Example:
3.6.2.2EXCHANGE ID (XID) REQUEST
…
/* startup a SAP */
event = SAP_ACTIVATION_REQUEST;
status = llc1_request(i,0,event,&lsap[i]);
…
/* define local sap */
source_id = 1;
/* define dest sap */
dest_id = 2;
MAC Packet SENDING
MAC Packet RECEIVING
Note: ACK (Acknowledgement) packets are not represented here
(SENDER)
Application
Indication
Request
Host
XID
XID
Burst
Burst
Alert
Alert
0x01
0x01
SRC
SRC
ID
ID
Logical Link
(SENDER)
Destination
DEST
DEST
Control
Source
ID
ID
SAP x
SAP x
DEST
DEST
ID
ID
Count
Count
FIGURE 6 - XID PROCEDURE
0x06
0x06
0x00
0x00
MAC Packet
(MAC Layer)
MAC Packet
DSAP
DSAP
MEDIUM
y
x
27
SSAP
SSAP
x
y
0xBF
0xAF
0x81
0x81
(RECEIVER)
Logical Link
Destination
0x01
0x01
Control
Source
SAP y
SAP y
0x02
0x02
CRC
CRC
CRC
CRC
(RECEIVER)
Application
Host