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Instrument Access
In addition, an instrument access code is necessary to maintain the instrument security and must
be entered or preprogrammed in appropriate software site list at the time of either successful level
one or level two serial links. Instrument default access code: 33333
How the ERX Recorder Works
The ERX Recorder utilizes a dedicated microprocessor in conjunction with precision sensors to
measure gas pressure(s) and temperature(s) and records the measured values in memory. The
electronic circuits are powered by a battery pack located inside of recorder case or by an external
power source. The applied power regulated to voltages required by the connected circuits. While
in the sample mode, most of the electronic circuitry is in an un-powered state (sleep mode) to
conserve battery power. When an internal timer has reached the selected sample interval time,
the electronics are energized and a sample measurement cycle begins.
When the recorder wakes-up and enters the sample measurement mode, the programmable
firmware instructs the microprocessor to obtain analog measurements. The analog signals
(pressure(s), temperature(s) and power) are multiplexed through the A/D converter and routed to
the microprocessor. The microprocessor converts and stores the digitized analog signals to an
equivalent numeric value, scaled to the selected engineering units. P1 pressure is stored in item
500; P2 pressure is stored in item 501; P3 pressure is stored in item 420; Gas temperature is
stored in item 502; Case temperature is stored in item 503: and power is stored in item 521.
Once the all the measurements are obtained, the microprocessor compares the measured values to
the parameter limits already in memory, i.e., high and low limits of pressure(s), temperature,
power, etc; if any of the measured parameters are out-of-range, the firmware instructs the
microprocessor to jump into an alarm subroutine. The alarm subroutine activates the appropriate
alarm code item(s), turns on the alarm indicator, transmits an alarm pulse out the alarm channel
and if equipped, activates a call-in, via a Messenger modem, CDMA…etc.
If during a sample measurement cycle wake-up the power supply voltage falls below the low
limit set points, the microprocessor activates the alarm indicator, transmits an alarm pulse out the
alarm channel, and, if equipped, activates a modem call-in.
After the microprocessor has completed the sample measurement cycle wake-up, the
microprocessor will update memory, display the new samples data to the LCD, and return to the
‘sleep mode’ to conserve energy.
Other than time, the ERX Recorder will also wake-up due to either a serial link or push button
activation. A wake-up caused by a serial communication link allows the recorder to
communicate with serial devices connected to J5 or through a COMS I/O port. A push button
activation access will cause the microprocessor to initiate the display list mode, as described on
page XXXXX. In all cases, the microprocessor will initiate a sample measurement cycle as
described earlier and continue to energize most circuits while the recorder is performing the user-
requested tasks.
Pressure System
(1 to 5000 PSI)
The pressure-sensing system incorporates one, two or three precision strain gauge transducer. The
transducers are housed in the ERX Recorder case and exit the case via 1/1” NPT female
connector.