6100 MPS-B Programming Manual

6100 MPS-B LINK MANAGEMENT

SELECT-TEXT State

A line is in SELECT-TEXT state when writing data, and whenever

it may write data, that is, between WRITE requests or when a

conversational reply is expected.

Transitions to SELECT-TEXT State

The following events cause a line to be in SELECT-TEXT state:

• The application makes a WRITE request to send the first

message. During data transfer, the line remains in

SELECT-TEXT state most of the time.

• The application makes a WRITEREAD request to send a

conversational reply. Although the line was in READ state

before the WRITEREAD request, it may change role when it sends

the conversational reply. If the station responds with ACK,

the line is in SELECT-TEXT state. If the station responds

with text, the line remains in READ state.

Transitions from SELECT-TEXT State

Transitions from SELECT-TEXT state to other states occur during

every protocol transaction. The following events leave a line

in some other state upon their completion (Figure 2-6 shows

various state transitions):

• The application makes a WRITEREAD request to transmit a

message and accept a conversational reply. Although the line

is in SELECT-TEXT state while transmitting the message, it may

change role when it accepts the conversational reply. By

using a READ request to send ACK, the line enters READ state;

by using a WRITE request to send text, the line remains in

SELECT-TEXT state.

• The application or the remote station sends an EOT sequence.

The state changes to CONTROL.

• The application sends a CONTROL DISCONNECT request, a modem

failure causes DSR to drop, or the application makes a STOP

request. The state changes to DISCONNECT; 6100 MPS-B reports

an error to the application.

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