EFLOW EF-Series - Automatic Self Tests; Diagnostic Monitoring; Real-Time Clock; RTD Input

Using the EF-Series Unit
2-12 Rev 2/01
2.4.6 RTD Input
The EF-Series unit supports a direct input from a Resistance Temperature Detector (RTD) sensor. The
terminals for the RTD wires are located at the bottom right of the Main Electronics Board and labeled
“RTD.” Refer to Figure 2-1. The RTD input is converted through a 16-bit RTD converter chip.
During operation, the RTD is read once per second. The value from the RTD is linearized, and then it
is sent to processing as Analog Input (AI) Point Number A3. The AI routine converts this value to
engineering units, performs calibration corrections, and checks alarming. The board temperature is
monitored by the RTD routine; if the temperature has changed by roughly 5° C or 9° F, the RTD
circuitry is sent a command to recalibrate its reference.
2.4.7 Real-Time Clock
The real-time clock provides the EF-Series unit with the time of day, month, year, and day of the week.
The time chip automatically switches to backup power when the Main Electronics board loses primary
input power. Backup power for the real-time clock comes from a supercapacitor (which also backs up
the non-volatile RAM), and is adequate for at least three weeks with no power applied to the EF-Series
unit.
2.4.8 Diagnostic Monitoring
The electronics board has three diagnostic inputs incorporated into the circuitry for monitoring battery
voltage, charging voltage, and board temperature. These inputs can be accessed by using the I/O
function of the ROCLINK Configuration Software. The three values are available as the following
Analog Input (AI) points:
♦ E1– battery voltage
♦ E2 – input/charging voltage
♦ E5 – board temperature
2.4.9 Automatic Self Tests
The EF-Series unit performs the following self tests on a periodic basis:
♦ Battery low and battery high.
♦ Software and hardware watchdog.
♦ RTD automatic temperature compensation.
♦ Sensor operation.
♦ Charging voltage for the supercapacitor.
♦ Memory validity.
The EF-Series unit operates with 6 to 15 volts of dc power. The LCD becomes active when input
power with the proper polarity and startup voltage (typically set at 10.6 volts or greater) is applied to
the POWER terminal block (provided the power input fusing/protection is operational). The battery
voltage tests ensure that the unit is operating in the optimum mode.