Hardware question - Programmable display?

[Lancie1]

Which model did you buy? They offer analog outputs to give you zero to ten volts...

Answer from Steelblue:

The Unitronics M91-2-R1 could be the winner! Only $230. Just need to get one here to try....OK... got the Unitronics M91 device here to play with,...

Unfortunately for Steelblue, that model only has an analog input, no analog output.

 

[PLCnewbie18]

Hi--Unitronics does offer a support forum:

http://forum.unitronics.com/

 

[Lancie1]

The problem I am facing now is the 10VDC (or 4-20ma) 'source' needed to make this work.

Steelblue, does your transducer say that you MUST use 10 volts DC to power it up? Most devices will work over some range of voltages, and you will need to scale your input to the Unitronics so that it will read the input as Minimum Elevation to Maximum Elevation, regardless of what voltage is being sent by the transducer. The important thing is usually to make sure that the transducer input voltage is constant, that it is regulated so that it does not vary over time and temperature. If it is 10 volts or 12 volts or somewhere in between, it should not matter as much as that it is ALWAYS the SAME voltage at the same position, so that your scaling equation in the Unitronics can convert the voltage or current input into the proper measurement range.

Another question is whether your Unitronics allows external voltages to be used for inputs. If not, you will have to use the Unitronics power supply voltage.

 

[steelblue48310]

Steelblue, does your transducer say that you MUST use 10 volts DC to power it up? Most devices will work over some range of voltages, and you will need to scale your input to the Unitronics so that it will read the input as Minimum Elevation to Maximum Elevation, regardless of what voltage is being sent by the transducer. The important thing is usually to make sure that the transducer input voltage is constant, that it is regulated so that it does not vary over time and temperature. If it is 10 volts or 12 volts or somewhere in between, it should not matter as much as that it is ALWAYS the SAME voltage at the same position, so that your scaling equation in the Unitronics can convert the voltage or current input into the proper measurement range.

Another question is whether your Unitronics allows external voltages to be used for inputs. If not, you will have to use the Unitronics power supply voltage.

Lancie... thanks for your thoughts. The 10 Volt supply is needed for the Analog 0-10V input to the U91 device, as a reference to the position of the linear transducer relative to the height of the machine. (The U91 can also accept a 4-20 ma input, which ultimately could be a much better choice.) The 'transducer' that I have is a passive device; nothing more than a 1K potentiometer with a 12" travel. It has a rated supply limit of 24V. Also, the maximimum analog input to the U91 that is allowed is only 10V, regardless of the scaling.

I agree that the supply voltage MUST be stable, else I will get unpredictable and undesired results... hence my concern for a 'real' 10 Volt supply, and not just a few resistors cobbled together. The signal conditioners mentioned in a few previous posts would be a perfect fit, but they seem to be a bit of overkill. (So much for my 'simple' project... )

The Digital Inputs do allow for 24 Volts, in either PNP or NPN configurations, so I shouldn't have any issues there.

~Mike

 

[steelblue48310]

Found a solution... I just ordered a different linear transducer that has it's own internal circuitry to control the 0-10V output. And it's $40 less than the 'potentimeter-style' transducer that I already have!

 

[BASIC ELECTRICAL TEC]

The Red Lion IAMA would convert that signal for you. However I'm not sure about the cost.

And then I've also used this handy little board, but I think it only goes one way with the signal :
http://www.kbelectronics.com/data_sheets/kbsi240d.pdf
It's very reliable in a long-term application.

 

[Lancie1]

Found a solution... I just ordered a different linear transducer that has it's own internal circuitry to control the 0-10V output.

Good deal. As Doctor Winchester said, "I do one thing at a time, I do it well, then I move on to the next".

Do you have your Unitronic program to read the new input and convert it to your elevations measurement written yet?

 

[steelblue48310]

Do you have your Unitronic program to read the new input and convert it to your elevations measurement written yet?

Working on that part this week... I'll use my normal method of learning a new product; Experiment, Observe, Repeat

~Mike