IOtech Digital488, Manual

Page: 27 / 64

3-6, Command Descriptions
7-17-01
Digital488 User’s Manual
When the Digital488 is addressed to talk ( R0 ) it asserts Inhibit , reads the data from all ports, unasserts
Inhibit and outputs the number of characters determined by the Gn and Pn commands. Leading zeros are
not suppressed and the bus terminators are appended to the output. After output the Digital488 must
be re-addressed to talk to perform subsequent reads. EDR ( R1 ) may also be used to capture data in this
format.
Example:
DIM A$[50] dimension the length of A$
CLEAR 718 reset the Digital488
OUTPUT 718;"C2G2X" configure ports 1 & 2 as output
OUTPUT 718;"D4E6BZX"
output hexadecimal
4E6B
to ports 1 & 2
ENTER 718; A$ read data from the Digital488
DISP A$ display shows
4E6B
F1 Format - ASCII Character
In the F1 format, the data is coded and transmitted in ASCII Characters with the four least significant bits
of each ASCII character representing four bits of data.
F1 Character Decimal Equiv F1 Character Decimal Equiv
0 0 8 8
1 1 9 9
2 2 : 10
3 3 ; 11
4 4 < 12
5 5 = 13
6 6 > 14
7 7 ? 15
Data received for output to the digital ports must be contained within a prefix ( D ) and a suffix ( Z ).
If the amount of data sent is less than the number of bits programmed as outputs, the least-significant bits
will contain the data sent and the most-significant bits will be cleared to logic zero. If the data sent
is greater than the number of bits programmed for output or selected by the
Pn command, the Digital488
will generate a conflict error and ignore the entire command string.
The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the
selected port(s).
When the Digital488 is addressed to talk ( R0 ) it asserts Inhibit , reads the data from all ports, unasserts
Inhibit and outputs the number of characters determined by the Gn and Pn commands. Leading zeros are
not suppressed and the bus terminators are appended to the output. After output the Digital488 must
be re-addressed to talk to perform subsequent reads. EDR ( R1 ) may also be used to capture data in this
format.
Example:
OUTPUT 718;"F1X" select ASCII Character format
ENTER 718; A$ read data from the Digital488
DISP A$ display shows
4>6;
OUTPUT 718;"D1??2ZX"
send 1??2 to the Digital488
ENTER 718; A$ read data from the Digital488
DISP A$ display shows
1??2