Envoy Application Programming Manual

File-System Procedures
Envoy Application Programming Manual—427159-001
C-8
CHANGELIST
For a tributary station, a call to the CHANGELIST procedure activates or deactivates the
station (with regard to either polling or selecting) by altering the setting of the poll bit or
select-state bit for a particular entry in the tributary’s address list.
The form of the CHANGELIST procedure is:
filenum input
INT:value
is the number returned by the OPEN call that opened the line. In a CHANGELIST call,
you supply this variable to Envoy.
function input
INT:value
is an integer value specifying what change is to be made.
parameter input
INT:value
is an integer value used in conjunction with the function value to specify what
change is to be made.
If the function value is >= 0, then the parameter value specifies whether you want
the poll bit or select-state bit set or cleared, as follows:
0 = cleared
1 = set
Note that the meaning of this bit is somewhat different depending upon whether the
address list is for a supervisor or tributary station. In a supervisor station, the poll bit
or select-state bit enables (clears) or disables (sets) the polling of the particular
tributary station. For a tributary station, the poll bit or select-state bit activates
(clears) or deactivates (sets) the station’s associated poll or select address.
CALL CHANGELIST ( filenum !i
, function !i
, parameter ); !i
>= 0 Change the poll bit or select-state bit. In this case, function also
specifies the relative address of the particular station address within
the address list. (0 indicates the first entry, 1 the second entry, and
so forth). The parameter value specifies whether you want the bit to
be set or cleared.
-1 Change polling type. The parameter value described below specifies
whether you want continuous polling or the poll list to be traversed a
finite number of times.
-2 Restore all partially disabled stations.