Raul

I added the rounding and filter function. I get a single reading now but every time I get to the part where the program reads weight, it gives a different reading with the exact same weight. I can only think the oscillation is still present due to the range of values I get on every reading.

Can I assume then that auto zero tracking will not solve this issue?

Hello, I don't have the means to measure frequency or waveform. Excitation is AC I am viewing the value on the HMI only. AC Voltage reading between +SG and +E is 2.4 V with or without load, same goes for -SG and -E. If measured as DC it oscillates between -5 mV and 5 mV. AC power is connected to a main switch then a fuse and then it goes into the power supply. The power supply is a Weidmuller CP SNT 70W 24V 3A. There is a fuse and then the EX-A1, then both IO-LC1's and then the PLC. (Daisy chained with 20AWG 600 V plastic coated copper wire). Only AC is grounded at the main switch. The distance between the loadcell and LC1 is less than 3 feet, the loadcells cable was not modified at all. It is a 4 wire cable, connected according to the LC1's wiring diagram for 4 cable loadcells. The power supply does not source anything other than what has been mentioned above. Tracking band, range and motion band were adjusted on the computer and fed to the PLC. The function is not present on the file I uploaded but they were located on the Loadcell calibration subroutine that is activated when you press the F1 key on the PLC and the HMI goes to the Loadcell calibration screen. I am located inside an empty warehouse, there are no engines, fluorescent lights, leds or anything that could cause interference. The power lines are only feeding this system right now, everything else has been disconnected. There is a 1HP water pump connected to the system but it is currently off. I am measuring thousandths of grams 000.000 up to 150 grams. The loadcell has been calibrated with 4 points. (0 grams, 10.6 grams, 18.9 grams and 143.9 grams) All weights were measured with lab equipment. Their weights remain more or less stable but the rightmost digit has the variation. If I reduce the number of digits, the variation moves to whatever the rightmost digit is. I tried rounding it, but the last digit remains constant and the next digit to its left inherits the variation. My personal guess was that the oscillation is due to the small mV variations that exist around the zero so I wanted to give the auto zero tracking function a try, but unfortunately I can't get it to work. Please bare with me, this is my first PLC project and I have read, studied, learned and re-read almost everything there is to Unitronics regarding this subject. Thank you.

Ideas anyone? I have contacted experienced PLC programmers in my country but none of them are familiar with this particular detail with Unitronics.

Everything is working fine with the loadcells except for a little oscillation. I have read the help file but I need more details and I did not find an example or useful topic in the forums regarding Auto zero tracking. This would really help me to get the precision I need by eliminating those little variations near the zero point. I'm attaching the application just in case you want to review it. I'm having problems defining the LC tracking band, LC tacking range and the LC motion band values. Not sure if I should use constants or MLs for this. Thank you. (The scale is set up from 0.000 grams to 999.999 grams, The oscillation is minimal but it prevents me from acquiring accurate data once it starts escalating.) V130_Celdas antes de auto zero.vlp

Hi, I have the same issue with the LC1, the loadcell manufacturer states that the shield does not need to be connected to anything. Should I try grounding the shield?

Hello, I would really appreciate if someone could tell me how to go about obtaining weight measurements and saving them to a table inside the PLC or into the SD card so that I can later export it to excel or any other kind of printable spreadsheet. Thanks

Hello, The loadcell works great, but I need to keep it from oscillating so much when it comes to the smaller readings. I set the scale to 000.0000 and rounded the last cero to 10. Is there something else I can do so that I can get a stable reading to 000.000? I'm measuring water drops so its a bit critical to be able to have a stable reading at this resolution.

Ok so this was much more simple than I thought. Thank you very much. I have one more question for you. How do I get the PLC to capture a weight value and store it on a table every cycle so that it can generate a report were I can read the weight change that occurred on each cycle? Exporting it to excel would be great but I just need to be able to print out a report on whatever format. Thanks

It is a Vision 130 33 RA 22, the loadcell module is the IO-LC1

I am very new to PLCs, but I have learned a lot during the past few weeks and I finally managed to program the routine I need except for the loadcells. I have read and re-read every single help topic and example available regarding loadcells. I have also consulted the new and old forums but I'm still stucked with this issue. I can place the loadcell calibration FB along with the scan, tare, zero and write to eeprom commands. I do get readings but unfortunately I'm afraid those readings are not being converted to actual grams. For some reason the read zero is not working for me. Also I have no idea on how to linearize the variable I'm using on the HMI. I know the Y range is 0-1000 grams but I have no clue regarding what should be set on the X range. The loadcells are 2.2 lbs made by FUTEK model LRF400. they have an RO of 2mV/V nom. and a zero balance of + - 3% of the RO. I'm not sure if I need to set the gain and offset for the LC, the reading between +SG and -SG is 0.1mV AC. I would really appreciate your help in order to finish this project.

Welcome Messages can be set up on the HMI. Just add a text box on the main display and then use links to the different screens you program on your HMI. Hope this helps.