COM20051 Datasheet, PDF(46/82 Page) List of Unclassifed Manufacturers – Integrated Microcontroller and ARCNET (ANSI 878.1) Interface

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

COM20051 Datasheet, PDF (46/82 Pages) List of Unclassifed Manufacturers – Integrated Microcontroller and ARCNET (ANSI 878.1) Interface

◁

DUPID bit is cleared. The user may then attempt

a new ID value, wait 840mS before checking the

Duplicate ID bit, and repeat the process until a

unique Node ID is found. At this point, the TX

Enable bit may be set to allow the node to join

the network. Once the node joins the network, a

reconfiguration occurs, as usual, thus setting the

MYRECON bit of the Diagnostic Status Register.

The Tentative ID Register may be used to build a

network map of all the nodes on the network,

even once the COM20051 has joined the

network. Once a value is placed in the Tentative

ID Register, the ARCNET core looks for a

response to a token whose DID matches the

Tentative ID Register. The software can record

this information and continue placing Tentative

ID values into the register to continue building

the network map. A complete network map is

only valid until nodes are added to or deleted

from the network. Note that a node cannot

detect the existence of the next logical node on

the network when using the Tentative ID. To

determine the next logical node, the software

should read the Next ID Register.

IMPROVED DIAGNOSTICS

The COM20051 allows the user to better

manage the operation of the network through the

use of the internal Diagnostic Status Register.

A high level on the My Reconfiguration

(MYRECON) bit indicates that the Token

Reception Timer of this node expired, causing a

reconfiguration by this node. After the

Reconfiguration (RECON) bit of the Status

interrupt service routine will typically read the

MYRECON bit of the Diagnostic Status Register.

Reading the Diagnostic Status Register resets

the MYRECON bit. Successive occurrences of a

logic "1" on the MYRECON bit indicates that a

problem exists with this node. At that point, the

transmitter should be disabled so that the entire

network is not held down while the node is being

evaluated.

The Duplicate ID (DUPID) bit is used before the

node joins the network to ensure that another

node with the same ID does not exist on the

network. Once it is determined that the ID in the

Node ID Register is unique, the software should

write a logic "1" to bit 5 of the Configuration

This allows the node to join the network.

The Receive Activity (RCVACT) bit of the

Diagnostic Status Register will be set to a logic

"1" whenever activity (logic "1") is detected on

the RXIN pin.

The Token Seen (TOKEN) bit is set to a logic "1"

whenever any token has been seen on the

network (except those tokens transmitted by this

node).

The RCVACT and TOKEN bits may help the

user to troubleshoot the network or the node. If

unusual events are occurring on the network, the

user may find it valuable to use the TXEN bit of

the Configuration Register to qualify events.

Different combinations of the RCVACT, TOKEN,

and TXEN bits, as shown indicate different

situations:

Normal Results:

RCVACT=1, TOKEN=1, TXEN=0: The node is

not part of the network. The network is operating

properly without this node.

RCVACT=1, TOKEN=1, TXEN=1: The node

sees receive activity and sees the token. The

basic transmit function is enabled. Network and

node are operating properly.

MYRECON=0, DUPID=0, RCVACT=1, TXEN=0,

TOKEN=1: Single node network.

▷