VISA Session Question

[GeekGrok]

Hello,

My question is generic and does not pertain to a specific test instrument. Instead I am trying to find out if VISA will allow me to keep track of a VISA instruments test settings (i.e. status).
For example, I am developing a TestStand sequence where each test step accesses the same VISA test equipment. Each test step may or may not set a different setting on the test equipment. Again as an example, one piece of test equipment is a VISA (GPIB) controller DC power supply that these test steps will access to perhaps set a different voltage setting. Test Step 1 will set the power supply output to 5 VDC, Test Step 2 will set the power supply output voltage to 4.5 VDC, and Test Step 3 will keep the power supply voltage set to 4.5 VDC.
Here's my question, is there a feature in the VISA driver that will keep track of the power supply's voltage setting so that when Test Step 3 is executed, I can use this feature in the VISA driver to see that the current setting on the power supply is what the test requires and thus eliminate the need to execute a write command to the power supply to set it's voltage output setting?
To put my question in simpler terms, does VISA have a way of keeping track of an instruments status (i.e. test settings)?

Thanks in advance for your time and response.

Thanx,
Jim

[LuI]

Jim,

no, AFIK there's no such thing.
This was more a device driver issue and as such is one or more levels up in the hierarchy.
If you'd get an IVI driver, those would keep track of the status of the device and eleminates unnecessary steps by its own.
What you could do is create a station global that holds the desired value or so. Than you could have a precondition for the step that changes the voltage. The precondition would be something like: "StationGlobal.Device.ActVoltage <> desiredVoltage 'Voltage must be changed"
and the step itself should have a post-execution substep that refreshes StationGlobal.Device.ActVoltage

Greetings from Germany!
--
Uwe