CONTROLINK86 SMSC, CONTROLINK86 Datasheet - Page 19

• 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
The SMSC Class 1 driver offers many services as detailed in Section C. Incoming packets from the
physical medium are received by the hardware and queued in system memory by an interrupt handler
located in the Low Level Driver (described in Section 4).
The following are the functions included in the Logical Link Control Layer software LLC1.C:
3.4LLC DATA STRUCTURES
LLC Layer relies on several basic data structures for keeping the status and passing parameters.
3.4.1 LLC_MSG DATA STRUCTURE (SAP)
The LLC uses the concept of service access points or SAPs. A SAP is a defined logical address within a
node and can be thought of as a ‘mailbox’. Incoming messages are sorted by ControLink and copied into
the appropriate SAP buffer or mailbox. SAPs can represent equipment codes, process parameters (i.e.
temperature, pressure), or protocol codes. A SAP can be local (LSAP), a destination (DSAP), global
(DSAP = 0xFF.), or a station SAP (SAP = 0). The station SAP is used for management of the entire node
and is defined as SAP zero. The destination SAP (DSAP) is the SAP of the node to which you wish to
send a command or data. SAPs are defined as either group or individual. ControLink uses a default
setting of 16 group and 16 individual SAPs per node. A maximum of 64 SAPs (group and individual) can
be accommodated. To change the default setting the MAX_SAPS definition in the LLC.H file should be
changed. The host system is not notified of a received packet unless the DSAP is activated within that
node. Thus packets not meaningful to this node are discarded. Note that SAP addresses are defined by
the system designer and have no physical relevance to the network. They are a convention for providing
independence from the networking hardware.
The request, indication, and service routines use a specific data structure to carry the required
information to and from the LLC1 and low level driver routines. The structure has the following elements
and is defined in the LLC.H header file.
The event, control, ssap, and dsap fields are filled in by the llc1_request() routine. The
dstation, group, msbcount, lsbcount, and *msgptr members must be entered by the user.
Function
llc1_service().
llc1_request()
llc1_indication()
llc1_group_indication()
struct LLC_MSG
{
USIGN8 event;
USIGN8 dstation;
USIGN8 ssap;
USIGN8 dsap;
USIGN8 group;
USIGN8 control;
USIGN8 msbcount;
USIGN8 lsbcount;
USIGN8 *msgptr;
};
Description
Routine is used to read, process, and route messages from
the queue into the appropriate SAP buffer. Class 1 services
are invoked through service Request/Indication routines
Used to send requests to ControLink and messages across
the network to SAPs belonging to other nodes. The request
routine processes the Logical Link Layer requests whether
they come from this Node’s upper layer or from the network.
Routines are used to notify the user that another SAP has
sent a command or data to a SAP (i.e. a packet was
received). Section 3.6 describes these routines in detail:
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