Main Content


(To be removed) Low-level memory read from VXI register

This visa object function will be removed in a future release. Use visadev object functions instead. For more information, see Compatibility Considerations.


out = mempeek(obj,offset)
out = mempeek(obj,offset,'precision')





The offset in the mapped memory space from which the data is read.


The number of bits to read from the memory address.


An array containing the returned value.


out = mempeek(obj,offset) reads a uint8 value from the mapped memory space specified by offset for the object obj. The value is returned to out.

out = mempeek(obj,offset,'precision') reads the number of bits specified by precision, from the mapped memory space specified by offset. precision can be uint8, uint16, or uint32, which instructs mempeek to read 8-, 16-, or 32-bit values, respectively. precision can also be single, which instructs mempeek to read single precision values.


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

vv = visa('keysight','VXI0::130::INSTR');

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


Perform a low-level read of the first and second instrument registers.

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

Unmap the memory and disconnect vv from the instrument.



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

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

offset indicates the offset in the mapped memory space from which the data is read. For example, if the mapped memory space begins at 200H, the offset is 2, and the precision is uint8, then the data is read from memory location 202H. If the precision is uint16, the data is read from 202H and 203H.

To increase speed, mempeek does not return error messages from the instrument.

Version History

Introduced before R2006a

collapse all

R2021a: visa object interface will be removed

Use of this function with a visa object will be removed. To access a VISA resource, use a visadev object with its functions and properties instead.

The recommended functionality has additional capabilities and improved performance. See Transition Your Code to visadev Interface for more information about using the recommended functionality.