If you are using a GPIB interface, you can simply use a GPIB control in
LabVIEW and send a few commands to the IOtech 488/80A. There are
plenty of examples in the manual. It basically comes down to
sending an initialization string (which includes the ports
configuration, and command format), and then sending the command to set
the pins HI/LO.
The initialization string I use is: C5P0F0G0K0R0Y3L0X
where...
Config Port 5 Port 4 Port 3 Port 2 Port 1
------ ------ ------ ------ ------ ------
C0 in
in in
in in
C1 in
in in
in out
C2 in
in in out
out
C3 in
in out out out
C4 in out
out out out
C5 out out
out out out
P0 = Select all 5 ports for input/output. Manufacter's default.
F0
= Use ASCII hexadecimal (4-bits per char) (e.g., the string "A1"
is translated to binary 10100001 (decimal 161)). Manufacturer's default.
G0 = Input and output port data are sent when
addressed to Talk. Manufacturer's default.
K0 = EOI (End-Or-Identify). Asserts EOI on last
byte transferred. Manufacturer's default.
R0 = Don't latch data. Read when whenever addressed. Manufacturer's default.
Y3 = Define line feed ('\n' in c/c++) as the
bus terminator.
L0 = Clears the internal data buffer.
X = Execute the above commands.
After sending this command, I check and clear any error conditions with
the E? command. Finally, I can send a command to set the pins
(this command assumes C5 config.):
P0XDxxxxxxxxxxZX where each lower-case "xx"
pair is a 2-digit hexadecimal number that represents the bit pattern
for that port, starting with port 5, then working down to port 1.
