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Samba SM43 - 4 - 20mA input issue


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Good day all,

I recently got a SM43 controller to create a control system for air compressors.

The issue I have currently with the input is a bit "strange" to me. I have configured AN0 as a 4 - 20 mA input, and connected a current loop simulator / generator to the unit as per diagrams included with the PLC. Since I am using a 2 wire transmitter / simulator I connected + of the simulator to the +24V and the - of the simulator to the AN0 (pin 9) of the PLC. What I am getting is very erratic jumping between 0 and about 90% on the reading. I tried it with a Druck UPS-II loop calibrator and a Fluke 787 in simulate mode, both with the same result.

My loop calibrator keeps on indicating "Loop", which points to an open loop, and my Fluke doesn't show any current flowing.

To me it almost looks like the input is set for 0 - 10 V instead, and a protection circuit is kicking in and out...

I am using Visilogic 9.8.65 Build 0. The latest "Beta" version my company's IT department doesn't want to install because it is labeled "Beta"....

 

What am I doing wrong...? What is the solution 🙂 ?

 

Thanks

Paul

 

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When you say configured did you do both the hardware(jumpers) as per the installation guide and the software in Visilogic??

Not sure which model you have but id you didn't open the unit up and move jumpers your working with a digital input.

Install guide links:

https://unitronicsplc.com/wp-content/uploads/2015/12/SMXX-J-T20_R20_DOC17015-A4_02-15.pdf

https://unitronicsplc.com/wp-content/uploads/2016/07/SM35_43_70_RA22_IG_2_16.pdf

https://unitronicsplc.com/wp-content/uploads/2015/12/SM35_43_70_TA22_IG_2_16.pdf

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Hi Cam,

 

Thanks for that hint. Yes, I forgot the jumpers. Now it looks good on one of my displays. However the same input, same config on another display does funny things. I have made a video of this. https://www.dropbox.com/s/qxhx64ljgs6c1qw/Input behaviour.mp4?dl=0 

 

The scale is 0 - 32 bar, for 4 - 20 mA. As you can see on one display it jumps to -7.92 bar (0 mA) while on the other display it works fine. The current injected is 16.03mA, which is 24 bars. (Correct scaling)

What am I running into here? Why is it working fine on one display, and not on another?

 

Thanks a lot in advance.

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  • MVP 2021

Nothing wrong with 9.8.65!!  I'm initially wondering if you aren't calling your reference properly, or you have it doubled up somewhere else by accident.  As Cam has just said, post your code if possible.  I've also seen strange things happen if there is an overlap of area on the screen.  Ensure this isn't happening.

cheers, Aus

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  • MVP 2021

On the screen issue, in theory it can't happen with Visi not letting you do it, but sometimes it does and needs an extra pixel clearance on what Visi lets you do as minimum etc.  I know this is a bit convoluted explain, but its the best I can do!

cheers, Aus

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38 minutes ago, Ausman said:

Nothing wrong with 9.8.65!! ...  I've also seen strange things happen if there is an overlap of area on the screen.  Ensure this isn't happening.

I mentioned the software version to give as much as possible information... 🙂

34 minutes ago, Ausman said:

On the screen issue, in theory it can't happen with Visi not letting you do it, but sometimes it does and needs an extra pixel clearance on what Visi lets you do as minimum etc.  I know this is a bit convoluted explain, but its the best I can do!

After removing the trend object on the display the problem disappeared...! The strange thing was that in the online test I could actually see the output of the linearization block was also jumping when the display was selected. 

Thanks a lot for the quick replies. Really appreciated! 🙂 

Now off to getting my "latched" buttons working.. I found a post about this, so I will try to implement that...

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  • MVP 2021
47 minutes ago, PaulZ said:

I could actually see the output of the linearization block was also jumping when the display was selected.

Glad it's fixed, but that still reeks of something interfering with the linearization operation.  Have you done a find on all your Linz operands to ensure there isn't one doubled up on use somewhere?  In any area of the row of an operand, right click to access the find/watch menus.

cheers, Aus

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@Ausman; I checked the code, and no double usage on the operand. Whatever I did size wise to the trend it didn't solve the issue. Removing it completely, saving the project, and inserting it back again (at exactly the same spot!) with the same settings / parameters made it work.. I'm a bit puzzled, but I am happy it is working 🙂

 

So now off to my next challenge of the latching buttons...  Thanks again for the help...  Paul

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I just done that, but during the editing the HMI decided to go to a full white display... No matter what I do, it remains white. Downloading the program still works, identification of the PLC still works, but just a white display 😞 

I will search the forums about this, but maybe I need to ship it back... I only had it since Saturday 😞 ....

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Tried it, no change.

I clicked on the 4th tab, and then check, and it started to "upgrade" the OS etc...? But now I think I have an older version. Before it was 4.4 (45) and now it is 4.4 (31) The rest is all the same version. After that again the Initialize & Reset, but still no luck.

 

PLC display.jpg

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13 minutes ago, Flex727 said:

Hold your finger on the screen for a full 5 seconds and see if it takes you to info mode.

Nothing changes on the display. When it starts up it is briefly darkish white, and then to full white as in the picture.

13 minutes ago, Flex727 said:

Post your program here also.

Empty program. Literally "New" program, selected HW config, and then download. I attached it anyway.

 

12 minutes ago, Ausman said:

Flex has just replied with his bit, but also ensure that when you worked on the jumpers internally that you haven't upset some other connection in the guts of the unit.  And in online mode, check SB8.

Checked all the connections, specifically the flat cable connection to the display, but nothing strange found. Re-inserted the cable too, made sure the latches were properly engaged..

image.png.661690800ca5378ff50ea17e02ab431a.png

4 minutes ago, Ausman said:

Also, if you have to update the O/S and this brings up the wizard, read everything on the wizard screens very carefully before progressing to the next one.

I did read it all.... When I try again it tells me that everything is up-to-date. See pictures below. Before the "upgrade", and during the upgrade. I took the screenshots at the same time...

2111748650_Beforeautomaticdownload.PNG.f255343a679cae4f80f0685a2e811b3e.PNGDowngrade..PNG.c6d196797e0520d97d1a07ee5a26bb54.PNG

empty.vlp

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  • MVP 2021

Great response, all there.  The O/S update all went though OK to the very end?  Perhaps pull the battery for an hour and reinsert?  Shouldn't make any difference, though.

Something weird going on, vot haf u done, munchkin?!!

Time for thinking caps and pondering....will advise.  The different boot and O/S numbers bother me....comments and research needed.

cheers, Aus

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  • MVP 2021

I'd perhaps be trying to get the O/S and boot back to what they were.  But before that, download a simple program that will react to physical inputs and give physical outputs without any screen interaction, and see if the plc is working those responses correctly.  If so, then that points to there being something fundamentally wrong with the screen.

cheers, Aus

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