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Need Help with RTD Setup

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Hello All

I am trying to get a Weed Instrument 611 RTD to give me a Temperature reading of a Caustic Solution, The Manufactures Information says


( Current: A Continues current of 20 mA (RMS) and a short term pulsed current of 40 mA (RMS) shall not Damage the sensor. Standard Operating current 1 to 4 mA )


So with this information I concluded the the Jumpers need to be set on Current and the Output needs to be a mA setup..I have tried 0-20 and 4-20 with no results.

I have 24V going to OV and V2 on the 24VDC Analog I/O connection and wired the RTD per the PT100 layout in the instructions with no results.


The RTD wires ( 3 of them ) are  Yellow,Black,Black, when i put my multi-meter that is set on ohms across the yellow and one of the black wires, i get a ohms value that converts to room temperature, I get the same value when I touch the other black wire, so I concluded that the yellow wire could possibly be the positive and put it on the + connection on I/O 0  and one of the Black wires on the negative connection with the second Black wire connected to the common. No results


Now after watching the Unitronics Video's on U-Tube they say that Linearization of the signal should not be needed, I have tried this as well and almost every combination of setup's there is...including some that i knew wouldn't work...At this point I am totally frustrated with trying to figure this out. I have been working on this particular part of the program for over two days with no results.


None of the Project Examples provided show how to build a setup for an RTD...they show everything else, but no RTD.


Can anyone out there in the Forum walk me thru this?


P.S. Sorry for the long drawn-out explanation.  






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For better help please provide more information, like RTD nominal resistance, link to RTD specification, full RTD model number (see p. 4 of document). etc.

It seems, that you are talking about next RTD:


Current parameters you mentioned are for maximum RTD load, which in most cases is not reached.

From this document follows, that there are 4 models of RTD sensors, 2x100 ohm, and 2x200 ohm.

Unitronics PLCs supports 100 ohm RTD.

You are not referring to PLC model. You can read V350 RA22 settings for RTD at following link:

http://www.unitronics.com/Downloads/Support/Technical Library/Vision Hardware/Vision350 Installation Guides/V350-35-RA22_J_DOC13005-A3_06-13.pdf

You have to configure Analog Input by jumpers, see page 4 and 6 for details, then configure it in VisiLogic Hardware Configuration as PT100 with corresponding "alpha" coefficient.

Then in linked to this Analog Input MI you will have temperature in 0.1 C. having 235, you have to read it as 23.5 C.

I hope this helps you to set it up.


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