The xDAC register class is used for reading and writing analogue
registers on VXI cards.
The class accepts raw data values in hexadecimal format or data in physical units. For example
the class understands 0.1kV, 100V or 100000mV as equivalent.
Attributes :-
-s VXI slot number
specifies the slot number (1-12) within the VXI crate. Manditory - no default value.
-c channel number
specifies the hardware channel within the VXI card. Optional. By default -c 0 is assumed.
Normally channel 0 is used for the configuration and common registers positioned at the base of
the card address space and channels 1 => n are used for the channel specific registers.
-a channel base address
specifies the address offset of the channel area relative to the base address of the VXI card.
This is the address offset within the card of the base of the channel 0 area. Optional.
By default -a 0 is assumed.
-z channel address size
specifies the address space allocated to each channel within the channel area of the VXI card.
Optional. By default -z 256 is assumed.
-o offset
specifies the address offset of the hardware register relative to the base of the current channel
within the VXI card. Manditory - no default value.
-w width of VME access. Options are 8; 16; 32.
specifies the data width required for accesses to the VXI hardware register.
-p access permission (rw, ro, wo)
specifies the data access modes permitted to the VXI hardware register.
Options are ro (read only); wo (write only); rw (read-write).
-u unit
specifies the SI unit to be used when returning data for read operations.
-q prefix
specifies the SI prefix to be used when returning data for read operations.
The following prefixes are understood: a (1.0e-18); f (1.0e-15); p (1.0e-12); n (1.0e-9);
u (1.0e-6); m(1.0e-3); c (0.01); d(0.1); h(100.0); k (1.0e3); M (1.0e6); G (1.0e9); T (1.0e12);
P (1.0e15); E (1.0e18).
-d decimal places
specifies the number of decimal places to be used when returning data for read operations.
Data being supplied for write operations may be in any format understood by the class.
-r range
specifies the calibration information to be used when converting data between real (physical) units
and digital (electronics) units.
The attribute format is minimum(digital):minimum(real),maximum(digital):maximum(real).
For example an 8 bit DAC may have -r0:0s,0xff:200ns which states that the minimum digital value
(0) is equivalent to 0secs and that the maximum digital value (255) is equivalent to 200 nsecs.
-i initial value
specifies the data value to be used by the INITIALISE operation. The register must also have write
permission.
The data value may be specified in real units. For example -i 100ns.
The absolute VME address of a register (relative to the card base address allocated by the
Resource Manager) is given by (channel area base address) + (channel number * channel size) + (register offset).