Measurement Computing Parallel488 - Manual (Page 21)

Section 3 Parallel To IEEE Operation
3.3
To configure the PC graphics system, connect the LPT output of the PC
to the parallel input connector on the Parallel488 using a standard printer
interface cable. Using a standard IEEE 488 cable, connect the Parallel488's
IEEE output to the plotter's IEEE input.
After configuration, turn on the plotter followed by the Parallel488. The
Parallel488's front panel LEDs should all light momentarily while it performs
an internal ROM and RAM test. All LEDs should go out except for the Power
and Talk LED. The Talk LED indicates that the Parallel488 has detected the
plotter on the IEEE bus and has addressed it to listen.
When the parallel host begins to send the Parallel488 data, the Receive
LED will flash. If it does not, this indicates that the interface is not receiving
data from the parallel host. Verify the cables are connected properly and the
parallel cable wiring.
The following is an example of how the Parallel488 can be used to
communicate with an IEEE plotter through the PC's LPT port. The program
example is written in Basic on an IBM PC or compatible. It turns the PC into a
dumb parallel terminal. When a key is pressed on the keyboard, the character is
transmitted out of the parallel (LPT1) port.
10 ' Terminal Program for the Parallel488
20 ' This Program allows direct interaction between
30 ' the IBM-PC and an IEEE plotter through the
Parallel488.
40
'
50 'Open the parallel communications port
60 OPEN "LPT1:" AS 1
70 ' Transmit key presses to the LPT1 port and
screen
80
K$=INKEY$
90 PRINT #1,K$; : PRINT K$;
100 GOTO 90 ' Do it again
Enter the program into the computer and run it. The example
below shows how to test the Parallel488'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 Parallel488's front panel LEDs as you type the plotter
commands.