What is Integrated Technician on the 2151/30?

What is Integrated Technician, and how can I best utilize this feature?

Integrated Technician is a diagnostic tool and requires analysis of the data to determine the scales condition. Using Integrated Technician you can monitor the Mv level output of each individual load cell/sensor.

Integrated Technician is a combination of hardware and software developed to perform “Off Line” system diagnostics.

Hardy Process Solutions offers a feature called INTEGRATED TECHNICIAN (IT) on most of its instrumentation. 
The modules (HI 1756 series, HI 1769 sereis) will use ladder logic to run the IT tests and read the data.
The HI 1746 WS module requires the WS 100 software to run IT.
The HI 2151/30 unit uses the front keypad functions for the IT features.
The HI 3030, 4000 series, and 6000 series can use both the front keypad, their built in browsers, or communications options to run and access the IT features.
All of the above instruments must have an IT capable summing card to have the IT features to be available.  Without the IT capable summing card, the instrument can get overall channel data but will not be able to get individual load cell data.

If you have only a single load cell attached to your scale controller, you do not need an IT summing junction cards. 

NOTE:  C2 cable is required and C2+ and C2- must be connect between the Integrated Technician summing junction card and the unit.  This connections allows communications to the summing card.  You do not need to have the Hardy C2 load cells to use the IT functions or IT summing card.  The IT tests will not function until a successful calibration has been performed.

The HI 3010 has a feature called SMART DIAGNOSTICS that is the same as IT, except you cannot use the HI 215IT summing junction box. The load cells are all directly connected to the back panel of the HI 3010. This means the controller will have to be installed extremely close to the scale to use this option.

The capabilities of IT are:

ON LINE DIAGNOSTICS: HI 2151/30, HI 1756WS, HI 1746WS
While the system is in normal operation (IT) continuously monitors excitation current to detect opens or shorts in load sensors, cables, or the junction box.

OFF LINE DIAGNOSTICS:
Digital Voltmeter: Used to read either millivolt or millivolt per volt signals from the system or individual load sensors*.

Return to Zero: Compares the weight readings at time of test to the weight readings at time of calibration. Readings available for the system or individual load sensors*.

System Test: Internal Reference: Substitutes a known voltage source in the instrument for the load sensor input.

Reference Box: Substitutes a known load in the summing box for the load sensor input*.

Load Sensors: Displays the weight readings for the system or individual load sensors*.

* Requires an IT capable Summing Box for a 4 load sensors maximum connection.

WEIGHING SYSTEM DIAGNOSTICS MADE EASY WITH INTEGRATED TECHNICIAN (IT)

Troubleshooting a weighing system (scale) can be very time consuming and costly. Isolating the scale component causing a problem is difficult to do without specific tools or training, and sometimes a “weighing expert” needs to be consulted. With the Integrated Technician (IT) feature of Hardy Process Solutions weighing components, the tools are already built into the weighing system to allow in-house personnel (or contracted weighing experts) to troubleshoot the system quickly and easily from the weight controllers front panel. This Tech Note will explain the Integrated Technician feature and show you how it will help you save time and money on your scale installation and system diagnostics.

Process weighing scales are usually the most reliable measurement systems in your facility. But when your scale has a problem it can stop production or make poor product.  Determining which component is the cause, replacing it and getting your system up and running quickly can be a challenge.

Often the problem with a weighing system is related to environmental or external influences. A ladder or bag of material inadvertently leaned up against a weigh vessel will cause binding. Welding on or near the weighing vessel can damage load cells (sensors). Load cell cables can be damaged by machinery or animals, and moisture in the weighing electronics or load cell cable, can alter weight readings significantly.

A process weighing system usually involves a vessel of some size and shape. The vessel sits on or is hung from load cells (anywhere from 1 to 4). These load cells convert the mechanical force of material in the vessel into a small analog electrical signal. The electrical signal from each load cell is normally routed to a junction box, where they are summed and then routed over a single cable to a weight controller. The weight controller digitizes the signal for local display and control. It can also convert weighing data to the proper protocol for PLCs or communications to other devices.

In the past when you had a weighing system problem you would call a “weighing expert” who would arrive with a variety of tools. These tools would include common hand tools as well as test devices such as multi meters and load cell simulators. Troubleshooting and manually isolating the faulty component usually meant going to the junction box, opening the junction box to read the millivolt output of each load cell.  Then performing a series of calculations to arrive at the respective weight values. This process is slow at best and requiring someone with an in-dept knowledge of weighing systems. In addition, these measurements can include climbing ladders and scaffolding, entering dirty or hazardous areas, and attempting to read load cell specifications from worn or missing labels. Meanwhile, production from the scale system is at a standstill.

Now, with Integrated Technician all of these operations can be accomplished from the front panel of your Hardy weight controller. When a problem is suspected, troubleshooting can begin immediately without the need for costly test equipment, which will increase your profitability.

As previously mentioned, troubleshooting a weighing system is a matter of isolating each component and verifying proper operation. With IT the process is quick because troubleshooting tests are done from your Hardy Instrument front panel or HMI screen, which is usually found in the comfort of the control room. There is no need to disconnect wires, perform complex calculations, or risk injury while attempting to take measurements from inaccessible junction boxes and load cells. From the front panel of your Hardy Instrument the operator can test portions of the weighing system. Since you are not breaking the integrity of the of the weighing system wiring, there is less of a chance of introducing new problems such as broken wires, loose connections, or mis-wiring when reconnecting the weighing system.

Readings are shown in pounds (or the current units selection), millivolt, or Millivolt per volt so no conversion is needed, and anyone familiar with the process can recognize suspected problems. Flow charts in the Hardy Installation User Manual can guide you through the troubleshooting process to find the symptoms and help determine the problem component. The manual can help you:
1. Isolate the instrument itself from the rest of the system to determine if it’s functioning properly. Using system test mode “SYSTST”, use the “INTREF” (internal reference)
2. The cable between the instrument and junction box along with the junction box itself is verified using the TSTBOX test.
3. If everything checks good to this point, you can read each load cell's output one at a time.

4.  Evenly add weight and repeat the test to insure each load point's millivolt signal reading increases.

If your load cells have Hardy's C2® Second Generation Calibration feature, the IT feature is helpful during scale installation or repair. A Hardy C2® load sensor has an internal memory device added to the load cell, which stores the load sensor’s performance parameters. You can compare this parameter to the IT reading to verify the load cell is reading correctly.

The Hardy controller will record the measured system resistance (base R), when the zero calibration value is being set during scale calibration. The current is calculated and this becomes the reference standard (right or wrong). The excitation monitor feature should be activated at this time. (HI 2151/30WC, HI 1756WS, HI 1769WS) If required, the base resistance and the current resistance can be displayed and compared manually at the weight controller’s front panel or HMI to aid in routine maintenance.

If the excitation monitor feature has detected a problem, we can use the Integrated Technician tools to isolate it. The simplest test to use is the Return To Zero Test. This test requires that the scale be empty, and uses the motion tolerance and the zero tolerance parameter values totaled as the acceptable range. The present zero voltage reading of each load cell is compared to the total of the motion tolerance and zero tolerance settings. If the two values agree an “Ok” is displayed, if they don’t an ERR message is displayed. Each load cell which displays an ERR isn't necessarily bad, but has a problem associated with it or with some portion of the weigh system connected to it. This can be a build up of material stuck to the inside of the vessel above the cell.

It can also indicate:
a. Mechanical binding within the vessel
b. Loose load cell mounting hardware
c. Supporting structural problems, such as broken welds, sagging I beams, missing shims or deteriorating support slabs
d. Poor or corroded electrical connections in the junction box wiring

The IT function DVMTST can also display the signal voltages of each of the load cells in the weigh system. This way preliminary checks use a digital Multi meter. You can choose to display the signals in millivolt with one digit to the right of the decimal point or in millivolt per volt with four digits to the right of the decimal. Both values displayed have an accuracy of five percent. A displayed voltage from one of the load cells that is out of range from the others will indicate a problem associated with components attached to it. As discussed previously, it does not necessarily indicate a bad load cell.  The built in digital volt meter is has limited range of 0 to 15mv.  If this range is exceeded the reading will read the extreme.  At this point the use of an actual Digital voltmeter is recommended to check the load cell output.  Large outputs (dc volts not milli volts) measured across the Signal + and Signal - are also an indication the load cell wires are incorrect.

Using the DVMTST is normally not enough information to determine the actual fault. A combination of tests will help test the system and help you determine the fault.

Frequently a process weigh scale will have multiple piping connections for material to enter and leave the vessel. If these pipes are not distributed equally and do not have flexible connections, the load cells will each generate a different signal voltage. Motors, vibrators, mixers and other auxiliary machinery mounted to one side of the vessel will also cause an imbalance in the signal voltages. When this is encountered, all the piping and the auxiliary equipment could be removed and the voltages compared.

The built in DVMTST is a handy feature for determining if the scale is level during an installation and reacting correctly to weight applied. Prior to attaching any piping, visually inspect the scale for mechanical soundness, tight mounting connections, no binding, etc. Record the signal voltages of each load cell. For the load cell with the lowest signal adjust the mounting hardware if possible, or add shims until the measured signal is as close to equal as the rest of your systems load cells.

To enter the DVM mode of operation consult the proper manual, LS1 is displayed for the first load cell as referenced in the IT summing junction box. View all the voltages for LS2, LS3, LS4 and LSALL If you have an IT junction box.

Note: A negative signal voltage is displayed as a 0.0 and can indicate out of range low and signals a system wiring, load cell installation or a major load cell defect. With voltage displayed at 15.3mv indicate an over ranged load cell, wiring, or major load cell defect.

System Test - Another diagnostic tool that IT provides is SYSTST (system test), and is used to display individual weights seen by the load cells and to isolates the weigh system component and compare them to some built in reference circuits. The same tests used in the DVM mode can be performed displaying weight values in pounds or kilograms rather than voltages. Weight displays can be less intimidating to some troubleshooters. Combining the finding of this test and the DVMTST a better picture can be developed. Applying weight on the scale and monitoring the reaction with the DVMTST or the SYSTST will pinpoint the load cell locations and ability to change weight and show stability.

To display weights enter the SYSTST consult you instrument manual. This can monitor internal and summing junction card reference points.

The Excitation monitor will usually not detect a drifting or unstable signal as displayed on the instruments front panel, which can be caused by any of the following:
The SYSTST can help determine the Following:
1. A fault in the instrument
2. Lost grounds or ground loops
3. Moisture in the load cell cable or junction box
4. Loose mounting hardware
5. Damage or overloading of the scale supporting structure
6. Loose strain gauges with the load cell

An electronic switch in the junction box is told by the instrument to disconnect all the load cells and engage a reference circuit within the junction box. The cable and instrument are now isolated from the load cells. If the symptoms are present check the shielding of the cable between the junction box and the instrument. The cable shield should only be grounded at the instrument. Examine the cable for cuts, breaks or kinks where moisture could have entered the cable. Ensure the cable is not bundled with any high voltage AC cable and is separated by at least three inches. Maintain 12"-14"separation from any 480 vac or magnetic fields. Also inspect the junction box for any moisture. Replace or reposition the cable and replace the junction box if necessary.

If the signal is stable the junction box reference circuit can be disengaged and each individual load cell in the system noting where the instability appears. Test all load cells in case there are multiple problems.

DVMTST will indicate the MV and Mv/V signal levels, but will not show a disconnected or no output signal voltage. You need to apply weight and then monitor for the proper change. For a second test use the SYSTST and confirm the INTREF test passes and then monitor weight changes to conform proper weight readings and reactions.