Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 273)

Chapter
Call Routines 69–127 13
13 -15
Use CALL 87 to determine if the DH-485 Common Interface File located
in the BASIC module was read by a device on the DH-485 Serial
Communications Link since the last time you checked.
Input and Output Arguments
This routine has no input arguments and one output argument. The output
argument is the DH-485 interface file remote read status:
0 – a device has not read from the DH-485 Common Interface File since
the last time you executed this call or since you powered up the BASIC
module, whichever occurred last.
1 – a device on the DH-485 Serial Communications Link has read the
DH-485 Common Interface File since the last time you executed this
call or since you powered up the BASIC module, whichever occurred
last.
Syntax
CALL 87
POP DH-485 interface file remote read status
Example
>1 REM EXAMPLE PROGRAM
>100 CALL 87 : REM CHECK FILE STATUS
>110 POP X : REM GET THE STATUS
>120 IF (X<>1) GOTO 100: REM WAIT ON DATA TO BE READ
CALL 87: Check DH-485
Interface File Remote Read
Status