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CHAPTER 4: Controller Operation
The following is an example of how this feature can be used to communicate
with an IEEE plotter. The program example is written in BASIC on an IBM
PC or compatible. It turns the PC into a dumb serial terminal. When a key
is pressed on the keyboard, the character is transmitted out of the serial
(COM1) port. Any serial data which is received from the port is printed
on the display.
10 ' Dumb Terminal Program for the interface converter
20 ' This program allows direct interaction between
30 ' the IBM PC and an IEEE plotter through the
40 ' interface converter. The interface converter must have Talk-Back
50 ' on Timeout enabled.
60 'Open the serial communications port
70 OPEN "COM1: 9600,n,8,2,cs,ds" AS 1
80 ' Display any data received from the COM1 port
90 IF LOC(1) THEN PRINT INPUT$(LOC(1),1);: GOTO 90
100 ' Transmit key presses to the COM1 port and screen
110 K$=INKEY$
120 PRINT #1, K$; : PRINT K$;
130 GOTO 90 ' Do it again
Enter the program into the computer and run it. The example below shows
how to test the interface converter’s operation with a Hewlett-Packard
®
7470A
plotter. Other IEEE plotters are similar, but you should refer to the plotter’s
programming manual for the proper command syntax. Notice the interface
converter’s front-panel LEDs as you type the plotter commands.
Type the following HP-GL
®
output-identify command on the keyboard...
OI;
The plotter (HP
®
7470A) should immediately respond with.....
7470A
When you type the following HP-GL command on the keyboard, the plotter
should respond by retrieving its pen, drawing a line and returning the pen.
SP1;PA1000,1000;PD;PA1000,6000;PU;SP0;