8
OPERATING INSTRUCTIONS
1. Make sure the alkaline batteries
have sufficient power. The display
will show the low battery symbol if
the batteries are inadequate. If the
instrument has not been used for
a period of time, the batteries
should be checked and replaced if
necessary. If desired, the AMM-15
can be operated from the AC
Adapter (it does not charge the
batteries). As with all such equip-
ment, if the unit is not to be used
for an extended period, the batter-
ies should be removed.
2. Purge the air line to be tested of
any water, oil, or other foreign
matter. The sensors are suscepti-
ble to contamination and damage
from impurities such as water, oil,
dust, chemicals, etc.
THE PRO-
VIDED FILTER MUST BE BE-
TWEEN THE AMM-15 AND THE
SYSTEM BEING SAMPLED
FROM. FAILURE TO USE THE
FILTER VOIDS THE WARRAN-
TY. OHMIC INSTRUMENTS IS
NOT RESPONSIBLE FOR MIS-
USE OR NEGLECT OF THE
UNIT.
3. Connect the AMM-15 to the air
line following the recommenda-
tions on the Sample Modes /
Connecting Information page.
[AIR LINE PRESSURE IS NOT
TO EXCEED 120 PSI]
4. Press the ON button. The AMM-
15 always displays Dewpoint on
power up. The DP / DB selector
button will change the displayed
parameter from Dewpoint to Dry
Bulb Temperature. The display
will show a "down" arrow when
displaying Dewpoint and an "up"
arrow when displaying Dry Bulb
Temperature. The °F / °C selector
button will change the displayed
parameter from degrees Fahren-
heit to degrees Celsius.
5. Allow sufficient time for the read-
ings to stabilize. Normal stabiliza-
tion will occur within 1 to 1-½
minutes. Very low readings, less
than -10°F DP, will take up to 10
or 15 minutes for stabilization.
Analog Output
The AMM-15 provides an analog
output of 0-1 VDC (from –55 to +95°
F Dew Point). Use the enclosed 2-
wire plug adapter, and connect a
voltmeter to the wires: Red/white to
positive (+) and black/white to nega-
tive (-). Plug the adapter into the jack
marked Analog Out, and see the
table on Page 13 for values.
RS-232 INTERFACE– Connect-
ing the AMM-15 to your Comput-
er
Connecting to a serial port The
AMM-15 can be plugged into any 9-
pin PC serial (COM) port using a 9-
pin serial cable, available from most
computer stores. If your computer
has a 25-pin COM port, 25-pin to 9-
pin serial adapters are also available
from most computer stores and can
be used with the cable [Serial data is
transmitted using Pin 5 (ground), Pin
3 (transmit), and Pin 2 (receive)].
Some computer COM ports and seri-
al adapters are not fully implemented
(not all pins are used). If the AMM-15
is connected to a partially implement-
ed serial port, functions may be errat-
ic or the unit may fail to communi-
cate. Please consult the owner’s
manual for your computer if this oc-
curs. Set up your communications
program as described on the next
page.
Содержание AMM-15
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