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Scaling or hardware setting issue?

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Hi there,


I am using a Unitronics US10-B5-RA28

I was hoping for some advice please. I believe I have some scaling issues on my proportional valve. I have it connected to an analog in and out. One to send it a setpoint from the HMI, and the other to read what its doing. The proportional valve is capable of doing 0-10 bar.

I am giving the value 2 bar to the proportional valve via the HMI.

I appear to be getting 2v from the analogue input which makes sense. 0-10v and 0-10bar (2v for 2 bar).

Although I am sending 2 bar and getting 2v on the multimeter it is telling me I am only getting 0.66bar. I have checked the actual pressure with a physical gauge and I am getting the 2 bar requested.

Any advice or something I may have missed?


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Yes the analog input settings are set correctly, both 0-10v as well as the outputs. The ranges are also the same on all.

I have since tried wiring the outputs straight into the inputs and giving the output a number. The input is reading is different to what i am giving the output which is strange

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As Gabriel said - how is your input scaled?  Try linearizing the input over the voltage range you want.  This will linearize a 14bit analog input over the 0-1000 mV range you need - setting input voltage equal to bar essentially.  2v = 2bar, 10v =10 bar


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Hi guys,

I have now tried starting a new project. Absolutely no ladder at all.

I have still got the analog outputs directly wired to the analog inputs. Output 0 to input 0, and output 1 to input 1.

I have scaled both inputs and outputs in the I/O settings to have a range from 0 to 10000, they are also both set to 0-10v.

I created a watch table for all 4 (analog input 0 and 1, and analog output 0 and 1).

If i understand correctly, if i send analog output 0 to a value of 1000 i should get 1000 back on the input? This is not the case i appear to get a value of 340 on the input. How can this be possible? The scaling is the same and one is directly connected to the other. I have checked the voltage and that appears to be correct just not the value of the input.

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That's irrelevant.  They still have to be linearized differently for different bit count.  14 bit input has to be linearized over 16383 range and the 12 bit out has to be linearized over 4095 to use full voltage range.

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  • MVP 2023

Merle, the point Gabriel is making is that hardware scaling is essentially fixed and can't be adjusted easily.  Ladder versions can.

JR, side question....Are you sure that you haven't got mixups in various settings, so that 4-20ma and other mistmatches are happening?

FYI.....Although this was made for Visilogic, perhaps it might be useful for your "play" and diagnostic purposes.  I'm sure the fundamentals are similar.  The whole point for me making it in the first place relates to Gabriel's similar use, where minor tweaking of some numbers in use gets things exactly right.  Online interaction and adjustment can then be done.  In my case in Visilogic, after tweaking I change values to permanent.


cheers, Aus

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**** SOLVED ****

Hi guys, thank you so much for your help over the last few days. It turns out that there was a dodgy earth to the 24V power supply feeding the Unitronics unit.

It was strange as everything else worked, it only seemed to be affecting the analog inputs to the unit. As soon as the earth was sorted i was getting the values i expected in the inputs from the outputs.

Thanks again guys for all of your time.

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