6100 MPS-B Programming Manual

6100 MPS-B LINK MANAGEMENT
READ State
READ State
A line is in READ state when reading text, and whenever an
acknowledgement is owed, that is, between READ requests.
Transitions to READ State
The following requests cause a line to be in READ state:
• The application makes a successful READ request to read the
first message. The state changes from CONTROL to POLL to
READ. During the series of READ requests, the line stays in
READ state most of the time.
• The application makes a WRITEREAD request to transmit a
message and accept a conversational reply. The line is in
SELECT-TEXT state while transmitting the message, but it
changes to READ state if it accepts a conversational reply.
By using a READ request to send an acknowledgement, the line
enters READ state; by using a WRITE request to send a text
reply, it in SELECT-TEXT state.
Transitions from READ State
Transitions from READ state to other states occur during every
protocol transaction. The following events leave a line in some
other state upon their completion (Figure 2-5 shows various state
transitions):
• 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 roles when it
sends the conversational reply. If the station responds with
ACK, the line state changes to SELECT-TEXT; if the station
responds with text, the line state continues to be READ.
• 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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