The bVXI register class is used for reading and writing data blocks to digital registers within VXI cards. Access to the hardware must involve only a single access via the VXI backplane for each data word.

The primary use of this class is accessing data buffers and lookup tables within VXI modules.

All address variables are VME addresses and are thus expressed in units of bytes (8 bits).

Attributes :-

-s    VXI slot number

specifies the slot number (1-12) within the VXI crate. Manditory - no default value.

-a    address

specifies the address offset of the data area relative to the base address of the VXI card.

-o    offset

specifies the address offset of the block access relative to the base of the data area within the VXI card.

-l    length

specifies the length of the data block in units of data items.

-w    width of VME access. Options are 8; 16; 32.

specifies the data width required for accesses to the VXI hardware.

-p    access permission (rw, ro, wo)

specifies the data access modes permitted to the VXI hardware. Options are ro (read only); wo (write only); rw (read-write).

-f    data format

specifies the data format to be used by READ operations. Data can be return in decimal (d) or hexadecimal (x). The default is hexadecimal.

-i    initial value

specifies the data value to be used by the INITIALISE operation. The register must also have write permission.

The absolute VME address of the start address of a block access (relative to the card base address allocated by the Resource Manager) is given by data area base address + block offset.

The WRITE and READ operations transfer a number (given by the -l attribute) of data words (of width given by the -w attribute).
The INITIALISE operation writes the data value given by the -i attribute to a number of locations given by the -l attribute. This is useful for setting all locations in a data buffer to a given value.