Stability test, Weight and voltage test, General policies and information – Hardy HI 1756-nDF User Manual
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Chapter 6
Warning
Do not install your HI 215IT summing board in areas susceptible to high vibrations. The
relays on the board can chatter and affect your weight readings and the vibration can
crystallize the solder joints.
To determine if an instrument or cabling problem exists, verify the basic operation of the
system by performing the following system checks.
Stability Test
The Stability test lets you check the A/D Raw count and average. With the IT option, it
tests and reports for each load cell. The test sends a fixed signal into the analog-to-digital
convertor and calculates the mean squared variation from the average reading, using 100
samples or 150 samples, depending on the Weight Update Rate parameter. The test
passes if the mean squared variation is less than 5.0.
If the weighing system passes the stability test, the results show OK and the variation and
mean results are posted. FAIL indicates that the Mean Squared Variation is greater than
5.0 so the instrument is considered unstable. In that case, see the Troubleshooting Flow
Charts Section.
CAUTION Do not perform the Stability Test during production. The test activities can cause
incorrect readings.
Weight and Voltage Test
The Weight and Voltage tests are used to diagnose a weighing system and, if certain
types of problems are indicated, determine their source. It provides the total scale input to
the instrument, such as mV/V and Weight in the units selected (i.e. lbs, kg, oz, g).
Running the IT test will show the weight and voltage results for each load sensor,
including the following values:
Weight: Weight value recorded on the sensor mV/V: The mV/V reading is sufficient to
balance the corners of your scale or vessel. These readings allow you to determine if the
problem is in the instrument (internal) or in a load sensor(s) (external). The normal
specification range for the Rate Controller is 0-15 mV. Readings outside this range (15.5
mV, 3.1 mV/V Maximum or any negative values), indicate an external problem. (Check
for improper wiring).
When you check the results, if all the load sensors read 0.00, something is probably
wrong between the HI 1756 nDF and the HI 215IT junction box, e.g., the cable may be
disconnected. Something could also be causing the box to not transmit the readings to the
HI 1756 nDF.
If you get no reading for one or possibly two or more load sensors (e.g., sensor 3 reads
0.00 or the reading is larger or smaller than it should be) and you know that the sensors
are connected to the junction box, either the load sensor is malfunctioning or its cable to
the junction box is loose or incorrectly wired.
General Policies and Information
Hardy Process Solutions provides world-wide support for its products. The following
paragraphs describe Hardy's customer support services and equipment warranty. When
returning a product, call the Technical Service Department listed below for a Return
Authorization Number. You will need to provide your company name, address, telephone
number, equipment model number, S/N, and a brief description of the problem.
NOTE
For all non-warranty repairs a purchase order or credit card information is required.
You can also go to the Hardy web site and request a Return Authorization number. An
RA# will be e-mailed to y