IEEE1451.4 Standard, ConRes + ConRelRes Datatypes

Question

I was wondering if someone could shed some light on the ConRes and ConRelRes data types that are listed in the IEEE1451.4. I am interested in writing a table for a bridge sensor (template 33). So for the row containing "Bridge element impedance", we will be using a 350-ohm bridge. What is the correct way to represent this value in binary ?

To give you the full picture I have been using a maxim integrated eeprom (ds2431) and hope to write the TEDs information to the memory. I have been using the java one-wire API that Maxim/Analog provides (One-Wire Java SDK) and it has worked so far in writing the basic TEDs table which has straightforward data types. But the ConRes and ConRelRes are not obvious to me. If anyone could explain this it would be much appreciated. I've attached images of the template, description of the data types, and a link to the IEEE standard. Thanks.

Bridge Sensor Template

Datatype Table

IEEE 1451.4

I see in the template that they give you a range and step increment. I think the possible values is the total span of the range divided by the step. I see that the value I get from this calculation matches up with the bits given in the field. But in my head I can't take it any further than that. I'm missing the big picture.

Answer 1

According to this

These data types map a set of integers onto a real interval. The <start_value> is the lower bound of this interval. The can be thought of as the granularity. The <number_of_bits> field determines the upper bound of the interval. ... For example, a standard 8-bit integer has a start value of -128 and a tolerance of 1

For example, ConRes allows you to say that the difference between every binary integer represents a difference of, say, 0.13 in the actual value.

In your case, start counting from 1 ohm in steps of 0.1 ohm and stop when you reach 350 ohm. The numbers of steps you took to reach 350 ohm is the value which represents 350 ohm.