CM4 Four-Point Continuous Monitor
CM4 Technical Manual
5-6
5.4.3 Selecting Signal Levels – Step
1. Press PROGRAM to exit Monitor Mode.
2. From the 1–CALIBRATION MODE, choose CALIBRATION
MENU, then the subfunction 3–CALIBRATE CURRENT
LOOP.
1 – CALIBRATION MODE
CALIBRATION MENU <>
3 – CAL CURRENT LOOP
The display reads:
SELECT POINT
3. Use the numeric keys to specify a point. The displays reads:
PT 1 CAL 1=MAN 2=RAMP 3=STEP
4. Press 3. The display shows the output for the selected point,
which will be set at 4 mA, whether or not a 2 mA fault operation
is enabled. The current loop can be lowered (decremented) to
20 mA if a 2 mA fault indication is enabled.
You are able to use the arrow keys to adjust the current loop from 4
mA to 20 mA in 1 mA increments. The display reads:
PT 2 CURR = 04 mA
PT 2 CURR = 07 mA
Press RESET twice to return to the Calibration MENU.
5.5 Function 1.4 – Tune Current Loop
Purpose
The Tune Current Loop function allows you to adjust the CM4 monitor’s
output level so that it is correlated from zero to full scale with a driven
device (an instrument used to monitor 4-20 mA output).
This is necessary only if new current loop hardware has been field
installed.
Instructions
To access Tune Current Loop:
1. Press PROGRAM to exit the Monitor Mode.
2. From the 1–CALIBRATION MODE, choose the subfunction
4–Tune Current Loop, then SELECT POINT.
1 – CALIBRATION MODE
4 – TUNE CURRENT LOOP
BOARD NOT FOUND
This message is displayed on newer CM4s if the optional current
output board is absent or defective.
LOAD DEFAULT 1=Y 0=N
T h i s m e s s a g e i s d i s p l a y e d o n l y o n n e w e r C M 4 s .
If “1” is chosen then the factory calibration parameters will be
loaded.
4 mA = 712
The user may change the DAC endpoint value corresponding
to 4 mA by pressing the arrow keys. However this should not
be performed without a known accurate external ammeter
and Technical Note T/N 1988-0040. Press <ENTER> to proceed.
20 mA = 3750
Similarly, this permits changing the 20 mA DAC endpoint. Press
<ENTER> to proceed.
SELECT POINT
The above procedure should be repeated for all four points.
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