User`s guide

150 VEE User’s Manual
3 Easy Ways to Control Instruments Chapter
Figure 94 A Direct I/O Transaction
In most cases, the process will be the same for sending text
commands to instruments. However, there are instruments that
specify characters sent at the end of each command or at the
end of a group of commands. You need to get this information
from the instrument documentation, then include it in the
Direct I/O Configuration dialog box.
Sending an Expression List to an Instrument
In some cases, you may want to send an expression list to an
instrument. For example, you may want to loop through a
number of frequencies in the Function Generator. To do so
using a Direct I/O Transaction, you would use a variable for the
frequency in an expression list, and add a data input for that
variable to the Direct I/O object. The following steps describe
how to send an expression list to an instrument.
1 Place a second Direct I/O object for the HP3325B in the Main
window. Double- click in the transaction area to get the I/O
Transaction dialog box.
You can use all of the defaults except for the command string.
In this case, use the format "FR", <frequency>, "HZ". This is an
Expression List, each expression being separated by
commas. The frequency is represented by variable A, which
will be a data input to the Direct I/O object.
2 Click on the input field for command strings and type
"FR",A,"HZ". (For example, if A were 100, VEE would send
the string "FR100HZ".) Click OK. Notice that VEE
automatically adds a data input pin labeled A.