Measurement Computing Digital488 - Manual (Page 44)

Section 3 Command Descriptions
3.14
Data received for output to the digital ports must be contained within a prefix
(D) and a suffix (Z) and each 4-bit quantity must be separated by semicolons. Leading
zeros are not required. 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;"F2X" select ASCII/binary mode
ENTER 718;A$ read data from the Digital488
DISP A$ display shows 0001;1111;1111;0001
OUTPUT 718;"D1111;0;1010;0101ZX"
ENTER 718; A$
read data from the Digital488
DISP A$ display shows 1111;0000;1010;0101
F3 Format - ASCII Decimal
In the F3 format, the data is described in decimal 8 bit multiples and transmitted
in ASCII. Each decimal number (0 to 255) to be output must be separated by semicolons.