General Monitors S216A, Инструкция по эксплуатации

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Power Supply (
continued
)
Terminal connections inside of the housing
have been provided for accepting the input
power.
fig ure 4
2.3 Con trol Elec tron ics
The control electronics are centered around an
eight bit microprocessor (figure 5). The
Sensor Signal, the CAL Switch, the Memory
(EEPROM), and certain Fault conditions are
monitored as inputs. By processing these
inputs, the following outputs are generated:
4-20mA Output Signal, Relay Contact States,
Digital Display Indications, and Calibration
Values (EEPROM).
As the microprocessor (MPU) receives and
processes the inputs, it determines what value
is output to the display, the 4-20mA current
generator, and the state of the relay contacts.
When the CAL Switch is activated, the MPU
allows the user to choose between the
Calibration, Test Gas, or the Alarm & Warn
Set Points and Relay Option Selection Modes.
While the unit is in the Test Gas Mode, the
MPU will fix the 4-20mA output signal to
1.5mA. The optional 0mA output signal is
for the calibration mode only.
Calibration Mode : When the unit is placed
in this mode, the MPU will look at the signal
from the sensor and determine when to accept
the calibration value. This value is stored in
the EEPROM and is used to adjust the digital
potentiometer associated with the Input Amp-
lifier. During calibration the
microprocessor will output a 1.5mA analog
signal (0mA is optional).
Calibration Check Mode : In this mode,
the MPU will output the gas concentration
to the display. When the gas concentration
drops below 5% of full scale, the unit will
return to normal operation. The purpose of
this mode is to check the response of the
unit to a known level of gas and determine
if calibration is necessary, while the output
current remains at 1.5mA (0.0mA is
optional).
fig ure 5
4
Sensor Assembly General Monitors