VTI Instruments Corporation
26
VM2710A Programming
N
OTATION
Keywords or parameters enclosed in square brackets ([ ]) are optional. If the optional part is a
keyword, the keyword can be included or left out. Omitting an optional parameter will cause its
default to be used.
Parameters are enclosed by angle brackets (< >). Braces ({ }),or curly brackets, are used to
enclose one or more parameters that may be included zero or more times. A vertical bar (|), read
as "or", is used to separate parameter alternatives.
R
EGISTER
A
CCESS
The VM2710A provides pseudo register access for high-speed data retrieval. The register is read
only and has 32-bit information accessible in two 16-bit parts.
There are two methods for accessing the 32-bit information. One method is to access the
information as a 32-bit data value with data-high and data-low retrieved from two 16-bit locations.
The second method is 32-bit access from one 16-bit location with the data-high/data-low
information alternating (data-high is first). This second method of data retrieval must be properly
synchronized otherwise the data would all be offset by 16 bits. The register map is specified in
Table 3-2.
The eight most significant bits of data-high contain data status and instrument function
information. The eight LSB of data-high, along with all 16 bits of data-low, contain the data
collected.
Figure 3-1
defines the 32 data bit assignments in the register. The instrument Function
and Range information (bits 24 through 28) is defined in
Table 3-1
.
Data-High
Data-Low
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Raw Data
Function and Range
Negative Overflow
Positive Overflow
F
IGURE
3-1:
R
EGISTER
A
CCESS
-
32-B
IT