Hardy HI 2151/30WC Single-Scale Controller - Manual (Page 15)

Chapter 1 - Overview
1-3
Excitation Monitor Continuously monitors the system excitation current for evidence of
open or shorted load sensors or damaged or broken excitation wire(s),
including the wires between the instrument and the junction box. If the
measured current deviates from a ± 10% tolerance, an "ERRExC"
(Error Excitation) displays on the front panel. In a system with C2 load
sensors, IT computes the correct current and displays alarms if the ini-
tial measured current is out of tolerance. Without C2 load sensors, the
initial read is assumed to be correct and is used as the standard.
Digital Volt Meter
(DVM) The DVM displays millivolts (mV to one digit to the right of the deci-
mal point) and millivolts per volt (mV/V to four digits to the right of
the decimal point) for both the whole system and individual load sen-
sors. The DVM helps enables the user to isolate a faulty component
from the front panel. The voltage reading can be used to level a bal-
anced system and to make corner adjustments to platform scales. Accu-
racy is ± 2% or better of full scale.
Return to Zero Test This test compares the original voltage reading saved at calibration
against the current voltage reading of an empty vessel and displays
either a pass (OK) or fail (ERR) message. The test checks for load sen-
sor damage (due to electrical zero shift or abnormal mechanical forces)
that causes binding sensors in the system.
• With an IT junction box, the test will pass or fail the individual load
sensors providing a true fault isolation capability.
• Without an IT junction box, the test will pass or fail on the basis of
a cumulative reading rather than an individual reading of each load
sensor.
Weighing System Tests (Requires the IT Junction Box) This test does the following analysis to
diagnose drifting or unstable weight reading problems:
1. It disconnects the controller and engages an internal reference sig-
nal to see if the problem is within the instrument.
2. It disconnects the load sensors and engages an internal (in the junc-
tion box) reference signal to see if the cable between the instrument
and the Junction Box is causing the problem.
3. It reads the weight of each load sensor to see if a load sensor might
be causing the problem.
Weight readings from the individual load sensors makes this test useful
for making cornering, leveling, and load-sharing adjustments.
Secure Memory
Module (SMM) The Secure Memory Module stores critical HI 2151/30WC configura-
tion, calibration and setup data (excluding Peak Hold) and protects it
from corruption. When a new parameter is entered during system oper-
ation, the SMM automatically updates that value in its memory. Since
the SMM is conveniently accessible from the instruments rear panel,
data stored in one HI 2151/30WC may be restored to the new instru-
ment by physically transferring the SMM.