RTDs: Dividing by 10

[kdcui]

This is somewhat a simple question:

Many of the RTD inputs I've seen have simply required a divide by 10 to get the "scaled" temperature.

Is this a result of how the RTD card works when taking the input (ie: does the RTD take care of the scaling)?

 

[TConnolly]

The card performs the linearization and conversion of the RTD resistance to a temperature. Converting an RTD sensor resistance to a temperature is not a trivial task.

Since an RTD can provide a very precise temperature measurement some RTD cards return the temperature in tenths of a degree. Allen Bradley RTD cards have a bit in the card configuration to select whether the card returns units of .1 or 1.0 degrees. If the card returns a value in tenths of a degree then dividing by 10 converts tenths of a degree to degrees.

 

[hanziou]

Allen-Bradley and Automation Direct Thermocouple cards also provide the option of temperature data in tenths of degrees. The modules perform the scaling and CJC calculations.

That is one of the features I'm willing to pay for to have a thermocouple card instead of a millivolt card.

 

[Bitmore]

Well, if you had been a bitmore informative about which PLC you have, what input you have on that PLC, how that input is configured, and what type of RTD you have connected to that input. I really cannot see how you expect advice or hep'.

Your information about the process is a bitless than I need to hep' you.

bitmore

 

[parky]

Mitsubishi RTD cards convert & scale the signal to X10 i.e. if the scale is 0-150 then the data is 0-1500 this is not a problem as you just use any comparison as temp x 10.
Most HMi's will also allow scale of 0-1500 give you 0-150.0 that is the value is an integer but displayed with decimal place (E series HMi's from Mitsi for example).
I think this is so you use simple maths rather than floating point (some smaller plc's do not do floats very well or not at all.