Measurement Specialties 9116 - Manual (Page 35)

Pressure Systems, Inc. Model 9116 User’s Manual
Page 26 www.PressureSystems.com
The Configure/Control Multi-Point Calibration (‘C’) command, actually 4 sub-commands, is
an improvement over the single calibration commands (‘h’ and ‘Z’) described above. Though
‘C’ provides for the adjustment of the same offset and gain correction coefficients already
described above, it does so with two or more applied pressure calibration points. The final
linear fit (i.e., new offset and gain correction coefficients) is a “least squares” correction fit
between all the calibration points specified. This ‘C’ command is particularly useful in
calibrating differential transducers over their entire negative-to-positive range.
Although the calculated offset and gain correction coefficients are kept in volatile memory
following execution of the calibration commands, they may be stored in non-volatile transducer
memory following the execution of the calibration commands (for use by all subsequent EU
conversions). This is accomplished with the Set/Do Operating Options (‘w’) command (Index
08 and 09).
The above correction coefficients are maintained internally in IEEE floating-point format. The
Read Internal Coefficients (‘u’) command and the Download Internal Coefficients (‘v’)
command can return (or manually set) calibration coefficients to the host in decimal or hex
dump formats in their responses.
3.1.4.4
Delivery of Acquired Data To Host
Several commands apply to host delivery of acquired data, either on demand or autonomously.
The Read High Precision Data (‘r’) command may be used to obtain high precision data
(selected channels in various formats). The modules also provide several high speed, high
resolution output commands. The Read High-Speed Data (‘b’) command is used to read “pure
binary” engineering unit pressure (all channels in the lowest overhead format). Use the ‘r’ and
‘b’ commands to get acquired data on demand.
The module can also deliver EU pressure data in streams, which consist of TCP/IP or UDP/IP
data packets that arrive autonomously in the host (with data from selected channels being
delivered in various formats at various rates). Up to three independent streams may be
configured, started, stopped, and cleared with the Define/Control Autonomous Host Streams
(‘c’) command. In conjunction with hardware triggering, this autonomous delivery method can
also make the module acquire (as well as deliver) data in its most efficient and time-
synchronized manner. This also frees the host to receive, process, or record these data in its
most efficient manner, since it need not waste time continually requesting new data with
commands.
The modules also have special purpose on demand data acquisition commands, including:
Read Transducer Voltages (‘V’) and Read Transducer Raw A/D Counts (‘a’), which provide
two views of raw pressure data. It has similar commands providing EU temperature ( C) and
other raw views of each channel’s special temperature signal, including Read Transducer
Temperatures (‘t’), Read Temperature A/D Counts (‘m’), and Read Temperature Voltages
(‘n’). This command group is generally used for diagnostic purposes. All of these special
purpose data (plus other module status information) may also be periodically delivered to the
host automatically in any of the three flexible autonomous streams configured by the ‘c’
command.