HP IBASIC Supplement 8-27
Interfacing with External Devices
Interfacing with an External Controller
Notice that the OUTPUT statement on line 460 is terminated with a
semicolon. This suppresses the line-feed that would otherwise occur.
As each line of the program is downloaded, it is checked for syntax.
If an error is found, the error message is displayed on the screen and the
line is commented and checked for syntax again. If it still causes an error
(for example the line may be too long), the line is discarded.
Any lines that currently exist in the memory buffer will remain unless
they are overwritten by downloaded program lines. This makes it easy to
edit lines in an external controller and then download only the edited
lines into an existing program. If you want to completely overwrite the
current program in memory, you must delete the program first. This can
be done remotely using the extended command PROG:DEL:ALL (see line
350 in the example program DOWNLOAD).
Uploading
The mnemonic PROG:DEF? is used to upload a program from the
program buffer. The entire program is then returned as a definite length
arbitrary block. A definite length block starts with the “#” character
followed by a single digit defining the number of following digits to read
as the block length.
Refer to the Example Programs Guide for a listing of the example
program UPLOAD, which demonstrates an uploading routine run on an
external controller.
The subroutine Openfile (lines 570 through 770) creates an ASCII file
in which to save the uploaded program. The number of 256 byte records
declared in the CREATE ASCII statement (line 730) is the file size
(declared in the definite block header) divided by 256. Line 720
accommodates any remainder in this calculation by increasing the file
size number by one record, if any remainder exists.
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