A lot of my time is spent explaining/verifying/demonstrating. The attached program shows the scan time for a V1040/V1210 and also demonstrates the logic required to do the same for any of the Enhanced family of PLCs.
SL20 - in V570 gives the scan time in units of 250 ns. In V130 and V350 - in units of 200 ns. In standard Vision models it's not supported.
Small tip - you can measure execution time of any part of your program via the function Interval. You can find it in VisiLogic > Utilities > Debug. It's described in Help topic On Line Test Mode.