The VM area of the LOGO! is a special memory area that the LOGO! using for sharing with remote devices.
Addressing:
Bit: V
Byte: VB
Word: VW
DWord: VD

For the user is allowed the range (addressing in bytes) can use for writing and read:
VB 0 to 850.
That means for bits:
V0.0 to V850.7
That means for bytes:
VB0 to VB850
That means for Words:
VW0 to V849
That means for DWords:
That means for bits:
VD0 to VD847
In the LOGO! can access via network input / output or via Parameter-VM-Mapping (under tools).

You must write or read in the LOGO! the VM addresses via network  input / output.

For example:
I1 > Network output with address V0.0.