Envoy Application Programming Manual

ADM-2 Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
7-8
Address-List Format
WRITE
Transmits data to a terminal. The call to WRITE causes Envoy to acknowledge the
preceding message with an ACK and then select the terminal indicated by the entry
number value in the message control word returned to the application’s write buffer.
Envoy transmits the associated text block from the write buffer when the terminal
acknowledges the selection. The WRITE procedure can also transmit sequential-
select, fast-select, and broadcast-select messages. A call to WRITE completes when
the selected terminal acknowledges the message.
WRITEREAD
Transmits a send-function selection sequence and then accepts the requested data
from the terminal.
Address-List Format
This subsection includes:
•
Terminal Address on page 7-9
•
Poll List on page 7-9
•
Select List on page 7-9
The address list tells Envoy the addresses of all terminals in the network that may be
polled or selected. The address list is passed to Envoy, after the line is opened and before
the first call to WRITE or READ, with a call to the DEFINELIST procedure.
Each entry in the address list is referenced by an ordinal entry number; the first is
designated entry number 0. Envoy uses the entry number, following a READ
completion, to tell the application process which terminal responded to the poll. The
application process uses the entry number, in conjunction with a WRITE call, to tell
Envoy which terminal is to be selected. The application process and Envoy pass the
entry number back and forth by way of the entry number field of the message control
word of the application’s read or write buffer.
Example 7-1
shows an address list that consists of a poll list followed by a select list.
Note. For a complete list of SETMODE procedures supported by the Envoy protocols, see the
SETMODE procedure description in Ta ble C-5 on page C-27, which also lists the analogous
modifier for these procedures.