Envoy Application Programming Manual

Table Of Contents
TINET Multipoint Supervisor Protocol
Envoy Application Programming Manual427159-001
8-5
File-System Procedures
File-System Procedures
The supervisor application process in a TINET multipoint network uses the following
Guardian 90 file-system procedures to interact with Envoy and to communicate with
tributary terminals:
AWAITIO
Waits for completion of an outstanding nowait I/O operation.
CHANGELIST
Performs any of the following functions:
Enables or disables polling or selection of a particular station
Alters the polling type (from continuous to noncontinuous or vice versa)
Causes Envoy to resume polling of partially disabled (nonresponding) stations
CHANGELIST may be called while polling is in progress, but does not take effect
until polling stops.
CLOSE
Terminates access to a data communications line.
CONTROL
Performs the line control operations shown in Table 8-3.
Table 8-2. Effect of the Timeout Value
Protocol State Effect of Timeout Value
During a WRITE Determines how long Envoy waits for an acknowledgment
During a READ Determines how long Envoy waits for an acknowledgment from a
polled station
Table 8-3. CONTROL Operations for TINET (page 1 of 2)
Operation Description
13 Sends EOT (end of transmission). This is used to clear the network after an
error occurs.
14 Sends ENQ. An ENQ code is sent to the transmitting terminal in response to
an error 173 (transmission error) on a READ. The receipt of the ENQ by the
terminal causes the terminal to clear itself (thereby destroying the data just
entered) and go into the RE-ENTER mode.