Setting up Load Cell Transmitter and Displaying Linearized Weight Values with SM70-J-T20 Samba PLC

[Samuel Austin]

I am a college student working on a project that utilizes the SM70JT20 PLC and Visilogic. I am attempting to wire a load cell to the PLC, receive the data through the analog 4-20mA input, linearize the data to a decimal weight value, and display the linearized value on the PLC’s screen. I followed the Visilogic manual on analog inputs and linearization, but currently the system is not functioning. I am unsure if this is a code or a hardware problem and would love a second opinion on the code and/or the wiring in an attempt to determine how best to proceed. 

For reference I am using the following load cell transmitter Load Cell Transmitter, Output 0-5V/0-10V/4-20mA | ATO.com and have attached my wiring diagram. Upon testing with a DMM the transmitter is powered and correctly outputs the current, so the problem seems to be on the PLC side. (Note that I have switched the jumpers on the PCB for analog current input).

 

Thank you in advance for any help and let me know if you have any questions!

Load_Cell_Test.vlp Transmitter_Wiring.pdf

[Flex727]

11 minutes ago, Samuel Austin said:

but currently the system is not functioning.

Can you provide a few details as to what exactly does "not functioning" mean? This is like saying "my car won't start" - can you tell me what's wrong?

Looking at your project file, everything there seems correct, with the exception of the display of MI 0 & MI 1. Both of these could be 4 digit numbers, but you have only allocated 3 digits to the HMI element.

[Samuel Austin]

6 hours ago, Flex727 said:

Can you provide a few details as to what exactly does "not functioning" mean? This is like saying "my car won't start" - can you tell me what's wrong?

Looking at your project file, everything there seems correct, with the exception of the display of MI 0 & MI 1. Both of these could be 4 digit numbers, but you have only allocated 3 digits to the HMI element.

Thank you for getting back to me. Currently I am trying to diagnose what is wrong, but I should have provided more details. The main goal of the program is to display both the raw data (which the load cell transmitter sends in the form of 4-20mA) and linearized decimal output of the load cell on the PLC. Currently the raw data is being displayed as zero and is not changing when a load is placed on the load cell. I used a multimeter to test the current outputted by the transmitter and it was correct, so the error is occurring somewhere either in the input wiring to the PLC or in the programs handling of the analog input. If there is anything still unclear let me know and I will try to go into more detail!

(I did change the MI 0 & MI 1 to displaying 4 digits, unfortunately it didn't solve the overarching problem, but it was a good catch nonetheless.)

[kratmel]

Please check jumpers. Yoou must set 4 jumpers for set AN0 and AN1 analog input to current mode.

Please post your multimeter connection setup diagram for test transmitter curent value.