Talking about the overhaul of electronic truck scale

Talking about the overhaul of electronic truck scale

Abstract: This article explains from a practical point of view how to accurately and reasonably determine and handle faults in the process of electronic weighing instrument maintenance truck scale weighbridge, and use examples to prove the necessity of determining faults and handling faults according to certain procedures, and summarize the basic methods of fault determination step.

Keywords: truck scale weighbridge, fault location, digital sensor digital load cell, internal code, communication interface

1:The characteristics of weighing instrument weighing indicator maintenance

In the era when electronic weighing instruments weighing indicator have completely replaced mechanical weighing instruments, the maintenance of weighing instruments will inevitably require matching methods and tools. When electronic products fail, there are new characteristics and rules to follow.

In our coal industry, including other industries, the overhaul of weighing instruments often requires high effectiveness. Take our Ningbo SAINTBOND for example. The equipment of the unit to be maintained by our measurement center is distributed within a radius of 200 kilometers. Once a failure occurs, the telephone time of the subordinate unit to report the fault is uncertain, but the coal sales and There is often no waiting for the purchase of re-weight.

This puts a lot of pressure on the maintenance, first of all, how to determine and deal with the fault in a short time, so that the equipment can be quickly overhauled and resume normal operation.

2:Fault judgment and location

According to the user's situation description and on-site survey, first of all, we must carefully check the entire system, especially to determine the type of failure, whether it is a software failure or a hardware failure. In practice, the author summarized the following summary process of fault identification.

Figure 1: Cheating device found on site

The process of "fault location" is particularly important. It can roughly determine whether the fault is a meter, a sensor weighing load cell or a transmission line. Of course, it may also be a multi-point fault.

To give a practical example: a 120t truck scale weighing scale in a coal mine has an empty scale weighing scale of 12 tons and cannot be cleared. Observed on the spot, the value is stable, and the fault remains after the power is turned off. Clean the cinder on both sides of the scale weighing scale body and near the limit. The fault cannot be eliminated. During the cleaning process, it is found that a foreign object is connected to a sensor weighing load cell line, which immediately caused Because of our high vigilance, carefully untie the plastic wrap-cheating device! This is the coal stolen device on the digital electronic truck scale that our bureau once again discovered. After reporting to the public security department to record photography and obtain evidence, we removed this device and turned on the power. The meter the weighing indicator showed that there was still an unremovable empty scale. What to do next? There is an opinion-directly do the zero point, but considering that the sensor weighing load cell has a different internal code Chang (No. 2), some concerns, the internal codes of each sensor weighing load cell:

No. 1: 600; No. 3: 1860; No. 5: 2360; No. 7: 740;

No. 2: 36320; No. 4: 1980; No. 6: 1460; No. 8: 1460.

Try to do a zero point calibration. The meter the weighing indicator can return to zero. It is also normal to compare the partial load with a weight of 10t, but when the amount of weight is increased (alternative method, weighed weight) to close to full weighing, the scale weighing scale The zero return is not good (about +200kg), decisively replace the No. 2 sensor, disconnect other sensors, connect the new sensor, modify the address, restore the connection to all the sensors weighing load cell, and the scale returns to normal (No. 2 is not connected to the cheat Sensor)-No partial load, normal after calibration, check the internal code of each sensor weighing load cell at this time:

No. 1: 440; No. 3: 2040; No. 5: 2320; No. 7: 780;

No. 2: 1400; No. 4: 1780; No. 6: 1540; No. 8: 1420 At this point, the overhaul is completed and it is approved for use.

The above example can be described as a series of twists and turns, not a single problem. In fact, the phenomenon that appears on the surface is similar to the above. Most of the problems are caused by the scale body being stuck after being deposited by coal mud. Sometimes it is displayed as a large negative value and sometimes displayed. It is a positive value, and the automatic tracking and resetting of the meter has a certain range. If it is too large, it cannot be automatically and manually reset. Generally, such problems should be cleaned up first, the scale is flexible, and the zero point can be re-calibrated, which can be adjusted appropriately The zero reset range of the instrument, for example, change the zero reset range from ±2% of full weighing to ±10%.

3:Reasonable steps for parameter adjustment

Some weighing instrument weighing indicator failures only need to adjust the relevant parameters, but there are also problems in the order of parameter adjustment. Here I will give another example. A mine phone reported that there was a problem with their truck scale. The specific manifestation was that the management computer connected to the weighing indicator could not display the data of the meter, and thus could not print out the door card. It was preliminarily determined that there was a problem with the communication between the computer and the instrument. On-site inspection process:

3.1: Check the communication line (use a multimeter to measure the on-off of the wire), use a laptop to send data in a specific format to the computer serial port, find the port breakdown, install a multi-serial port card, and install the driver.

3.2: At the same time, use a wave tester to test the serial port of the instrument. The normal waveform should be the square wave on the left in Figure 2 and the clutter on the right. It can be concluded that the serial port is broken, and the waveform on the right is the waveform measured on the spot. If there is no tester, you can use another method: let the computer read the meter data (you can use the terminal emulation software that comes with XP, or use the serial port assistant software), and it still can’t be read when the port and baud rate are correct. It can be concluded that the mouth has been damaged. In this way, it is recommended to install a photoelectric isolator to protect the computer serial port.

Figure 2 Serial port waveform

3.3:To replace the instrument (XK3190), first read out all the parameters of the old instrument weighing indicator(can be connected to a printer for printing) and record as follows:

CALI: 751834…………………………Calibration coefficient

ZERO: 66457………………………………Zero point value

1#L/Ｃ：9994130……………………Sensor load cell coefficient

2#Ｌ/Ｃ：9996164

3#Ｌ/Ｃ：10006216

4#Ｌ/Ｃ：10005592

5#Ｌ/Ｃ：9993159

6#Ｌ/Ｃ：9999542

7#Ｌ/Ｃ：9991994

8#Ｌ/Ｃ：10004437

１#Ｌ/Ｃ0：6634……………………………Sensor load cell zero point parameters

2#Ｌ/Ｃ0：4041

3#Ｌ/Ｃ0：8581

4#Ｌ/Ｃ0：12515

5#Ｌ/Ｃ0：11572

6#Ｌ/Ｃ0：11521

7#Ｌ/Ｃ0：8945

8#Ｌ/Ｃ0：2657

１#Ｌ/ＣID：0022084………………………Sensor load cell address identification code

2#Ｌ/ＣID：0022052

3#Ｌ/ＣID：0022115

4#Ｌ/ＣID：0022071

5#Ｌ/ＣID：0022106

6#Ｌ/ＣID：0022055

7#Ｌ/ＣID：0022064

8#Ｌ/ＣID：0022234

DIVI:20………………………………………load cell index value

SPAN:10000…………………………………load cell max. capacity

Replace the old instrument weighing indicator and switch on the new instrument. Please be careful not to enter the sensor weighing load cell address and related parameters. The correct steps are:

① Modify the scale weighing scale value and maximum weighing of the instrument weighing indicator;

②Enter the sensor weighing load cell address and related parameters and ensure that they are accurate;

③Adjust the serial port data format and baud rate of the instrument.

3.4: Restart the meter weighing indicator, observe the zero point of the meter and test the partial load and weighing of the scale body, and resume use after normal. The above steps have a certain logical relationship and cannot be reversed. According to experience, if you modify the input sensor address and related parameters first, and then modify the index value and maximum weighing, the meter display will deviate seriously from the zero point. If the sensor parameters are input incorrectly, the partial load of the scale weighing scale will be very abnormal.

4:Summary and suggestions

The verification and maintenance of weighing instruments is a very important task, and the cause of the failure is complicated. The industry has issued related verification procedures for the verification work. There are still rules to follow, but the maintenance work has not yet been able to formulate professional specifications and procedures. The reason There are many aspects. The first is the diversification of instruments, and the operation is very different. In our mining area alone, there are three types of instruments from manufacturers: Ningbo GOLDSHINE, Ningbo SAINTBOND, and each manufacturer has its own series of instruments. The author thinks whether it is possible for the industry to formulate large standard steps, and each manufacturer cooperates to formulate specific process frameworks according to their own characteristics, so that the formation of specifications can allow newcomers to master maintenance skills faster, avoid detours and detours, and train them as soon as possible A capable and skilled professional technical team, this is the result that major manufacturers are willing to see.