EQUIVALENT INPUT can be approximated from a knowledge of the Shunt Cali-
bration Resistance (R); the transducer's Bridge Resistance (B); and the transduc-
er's Full-Scale Sensitivity (K, in mV/V, full scale).
To determine the EQUIVALENT INPUT (X) as an approximate percentage of full-
scale output, you may use the following equation:
a. Perform Steps a through f of the "Actual" two-point calibration procedure
given above.
b. Press ENTER. The unit will display "SHP" (for SHUNT CALIBRATION—POSI-
TIVE).
c. If you want to switch in the shunt resistor for a positive up-scale reading, press
ENTER once again and proceed to Step d. If you want to switch in the shunt
resistor for a negative up-scale reading, press the CAL button to display
"SHN" (for "SHUNT CALIBRATION—NEGATIVE"), and press ENTER.
d. After you press ENTER, the 3570/3578 will show the status of the selected
shunt: "ON" means that the shunt is connected; "OFF," that it is not. If the
shunt is currently OFF, turn it ON by pressing the top or bottom segment of
any displayed character, followed by ENTER. This will return you temporarily
to a display of the "live" analog input.
NOTE: By turning ON either of the two shunts, you will automatically turn OFF the
other one (if it is presently ON).
ALSO NOTE: Toggling the "SHP" or "SHN" display to ON is equivalent to entering a
command of SHP=ON [CMT] or SHN=ON [CMT], respectively, through the RS-
232/485 Interface. Toggling a shunt to OFF is equivalent to entering a command
of SHP=OFF [CMT] or SHN=OFF [CMT]. As explained in Section 1.f, the state of
the instrument's positive and negative calibration shunts can also be controlled
by means of logic inputs to the rear-panel Analog Input Connector. However, if
the unit receives contradictory shunt commands from the keypad/interface and
from a shunt-control logic input, it will return to normal "live" measurement.
e. Now freeze the displayed data value by pressing ANY KEY EXCEPT CAL OR
SETUP.
f. Using the NUMERIC BUTTONS, change the displayed value to the known
EQUIVALENT INPUT produced by the shunt, with appropriate polarity. As
before, this second calibration entry also sets the desired measurement pre-
cision.
g. Press ENTER to establish your second calibration point. The display will
return to "FORCE."
h. Press the CAL button. The display will return to "OFSET." Note that pressing
the CAL button will automatically turn OFF whichever shunt is presently ON,
so that normal measurement will resume as soon as you return the condition-
er to "RUN" mode.
i. To exit the CAL button sequence and return to the "Setup" display, press
SETUP.
4.11
SETUP: INSTRUMENT CALIBRATION
4
4.c CALIBRATING THROUGH THE FRONT PANEL
X
=
%
25000(mV/V)B
KR
To Next Page
Loading...
Need help?
General
