Instrument Control Toolbox

memmap

Map memory for low-level memory read and write operations

Syntax

• memmap(obj,'adrspace',offset,size)
  

Arguments

obj	A VISA-VXI or VISA-GPIB-VXI object.
'adrspace'	The memory address space.
offset	Offset for the memory address space.
size	Number of bytes to map.

Description

memmap(obj,'adrspace',offset,size) maps the amount of memory specified by size in address space, adrspace with an offset, offset. You can configure adrspace to A16 (A16 address space), A24 (A24 address space), or A32 (A32 address space).

Remarks

Before you can map memory, obj must be connected to the instrument with the fopen function. A connected instrument object has a Status property value of open. An error is returned if you attempt to map memory while obj is not connected to the instrument.

To unmap the memory, use the memunmap function. If memory is mapped and fclose is called, the memory is unmapped before the object is disconnected from the instrument.

The MappedMemorySize property returns the size of the memory space mapped. You must map the memory space before using the mempoke or mempeek function.

Example

Create the VISA-VXI object vv associated with a VXI chassis with index 0, and an Agilent E1432A digitizer with logical address 130.

• vv = visa('agilent','VXI0::130::INSTR');
  fopen(vv)
  

Use memmap to map 16 bytes in the A16 address space.

• memmap(vv,'A16',0,16)
  

Read the first and second instrument registers.

• reg1 = mempeek(vv,0,'uint16');
  reg2 = mempeek(vv,2,'uint16');
  

Unmap the memory and disconnect vv from the instrument.

• memunmap(vv)
  fclose(vv)
  

See Also

Functions

fopen, fclose, mempeek, mempoke, memunmap

Properties

MappedMemorySize, Status

load

mempeek