Measurement Specialties 9116 - Manual (Page 40)

Pressure Systems, Inc. Model 9116 User’s Manual
Page 31 www.PressureSystems.com
CONFIGURE/CONTROL MULTI-POINT CALIBRATION (Command ‘C’)
Purpose: This
command is actually four (4) sub-commands. The first configures and starts
a Multi-Point Calibration adjustment function for selected channels in the
module. Another is repeated multiple times to collect data for each defined
calibration point. Another ends the calibration function normally by calculating
new offset and gain adjustment coefficients from the collected data. It then
returns the module to its normal state, but with improved accuracy. A final sub-
command is used only if it becomes necessary to abort the calibration function
while in progress. The general form of all sub-commands is described in the
table below. Subsequent pages separately describe each individual sub-
command and give examples of each.
Command
“C ii[ dddd]... ”
‘C’ is the command letter.
‘ ii’ is a required sub-command index preceded by a space character.
‘ dddd’ are zero or more optional datum (or parameter) fields, each
preceded by a space character. These vary with the sub-command used.
Response
Depends upon the particular sub-command (ii) used.
Description: The four ‘C’ sub-commands configure and control operation of a Multi-Point
Calibration function that is similar to the simpler re-zero and span calibration
adjustment functions (see separate ‘h’ and ‘Z’ commands). However, ‘C’ adjusts
both the offset and gain correction coefficients of each affected transducer at the
same time, using two or more calibration points. Thus, instead of simply
calculating a new linear (i.e., straight line) adjustment function that passes
through the supplied zero and span calibration points, it calculates a best-fit
straight line, using the least squares method, that comes “as close as
possible” to all the supplied calibration points. This correction method
provides the very best adjustment throughout the entire range (negative to
positive) of a differential transducer.
Note
Avoid confusing this Calibrate command ‘C’ (upper case C) with the
Configure/Control Autonomous Host Streams command ‘c’ (lower
case c). Like “c,” but unlike most other module commands, all sub-
commands of this command require a space between the command
id (‘C’) and the first parameter (ii).