Retrieving AI Max (Temperature) Values with Channel Property Node

[tperson]

I am trying to retrieve the AI signal input range as defined in MAX. When using a channel property node the maximum AI value returns 2191 and change while the minimum is returned as -345.XXX. This is not the input range as defined in MAX. What type of scaling is done between setting the min/max value using a "Create AI Temp TC Channel" (also in attachement and the channel property node? How can I retrieve this data?

Thanks

tom

[Steve_B]

Hi Tom,

The properties that you are using (AI.Max/Min) are returning the coerced max/min value based on the values that you set in the DAQmx Create Channel VI. The values are returned in the same units that you specify when you create the task. There are also properties (AI.Rng.High/AI.Rng.Low) which return the coerced range max/min in the default units for the device. Those numbers should correspond between the different properties based on the voltage to temperature conversion.

You can look at the actual range specified in the units for the device and compare it to the actual ranges for your card. I was testing this on a PCI-6251 which has ±10 V, ±5 V, ±2 V, ±1 V, ±0.5 V, ±0.2 V, and ±0.1 V ranges. The ranges were being coerced to the ±0.1 V range because there was no smaller range for the card to be in. The maximum range defined in Fahrenheit for a J Type Thermocouple is 2191.93 to -345.954 degrees. The entire range for a J Type thermocouple fits within that range of voltage values. This is why the temperature range values I set were being coerced to the same range values.

[tperson]

Steve,

    Thanks for the quick response. I actually gave up on this idea and found a work-around.

Thanks again

Tom