RC Systems ST-72, Instruction Manual

Page: 37 / 142

ST-72 User's Manual
Document: UM-1007 Revision Level A
31
Unity Gain resets zero offset to 0 and span gain to 1. It is useful for returning the
calibration to a known starting place. Sensor aging may be monitored by recording zero
and span readings at
Unity Gain when it is new, and again at later dates when
degradation may have occurred.
To check zero calibration, apply the ZERO calibration value to the sensor and observe
the live reading. If the zero reading differs from the zero setpoint, a calibration is
needed. To calibrate zero, move the highlight bar to
Set Zero
and press
Edit
. A
warning message explains that pressing
Edit
again will change the zero calibration and
any other key will exit. The procedure for span calibration is identical. For example, if a
gas sensor is to be spanned with 50% span gas, the span set-point must be 50%. If 45%
is to be used later, the span set-point must be changed to 45% to match the span
calibration gas. If the reading is only 40% with the 50% gas applied, a span calibration is
needed. Move the pointer to the
Set Span
entry and press
Edit
twice.
Unity Gain
may be used at anytime to cancel incorrect calibrations and start again.
2.4.4.5 MARKER MENU
Some transmitters or monitoring devices providing ST-72 inputs also indicate special
modes of operation, such as
Calibration, Maintenance or Fault, by transmitting a special
<4mA or negative “Marker” value. The ST-72 offers channel Marker menus for
detecting and indicating such events (see Figure 2-18). While active, the ST-72diplays a
6-digit ASCII message to indicate the special event and if equipped with 10-0348 4-20mA
output option, the ST-72 also transmits the same <4mA value.
200
1000
10
COM1
~
Ch. 38 Data From
Min Raw
Max Raw
Remote ID
Interface
Marker Menu
Src Wireless Monitor
-16
IN CAL
Yes
Ch. 38 Marker Menu
Marker %
Mark as
Sensor Life
Marker Enabled Yes
Figure 2-18
2.4.4.5.1 Marker Enabled
Turns the marker feature ON and OFF