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MODEL 1793/6423
OPERATION
3-11. Using the 1793/6423 with the PET Computer.
The standard PET Computer comes with an IEEE 488
Port which can be used as a low cost controller.
A
limitation of the PET, however, is
that
once
a
device has been addressed to talk, it must respond
within 65msec. If a response is not received within
this time, the PET will proceed to the next BASIC
instruction.
Table 3-5 is a suggested method to
circumvent this limitation of the PET.
3-12.
To get a 400msec triggered reading with pro
gram in Table 3-5, change the address to 25. To get
a 1.2 sec. triggered reading, add the FOR NEXT loop
as shown in Table 3-6.
3-13.
It
is
not
recommended
to
use Secondary
Addressing with the 1793/6423 and the PET due to the
timing limitation.
TABLE 3-5
Program for the 1793/6423 and the PET.
TABLE 3-6
Program for a 1.2 Sec. Triggered Reading
BASIC INSTRUCTIONS
REMARKS
10
OPEN 1,24
I, is the logical file num
ber. 24 is the Primary
Address (can be from 4 to
29).
20
INPUT #1,0$
DATA is inputted to file
I
from device with Primary
Address 24. D$ is the name
given to the incoming data.
30
IF ST=2 THEN 20
ST is the status bit; TIME
OUT Read error. The pro
gram remains in this loop
until data is received.
40
PRINT D$
The incoming data is
printed on the CRT.
BASIC INSTRUCTION
10
OPEN 1,25
15
FOR N = 1 to 3
20
INPUT# 1,D$
30
IF ST=2 THEN 20
35
NEXT N
40
PRINT D$
REMARKS
This loop gets 3 readings,
but only outputs the latest
reading.
End of loop.
*Remarks same as Table 3-5
3-3
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