IPMI temperature sensor precision/type

Question

When I query the T_AMB sensor of a Sun Server X4-L using IPMI, using the rmcp interface in a simple python-ipmi based program (which uses the GetSensorReading IPMI command to get a sensor reading every second), the value of the sensor comes out as float without any fraction (say 28.0 C). When I display the value of the sensor using the show /SYS/T_AMB from the Service Processor console, it is displayed as float with non zero fraction (fluctuates between 27.750 and 28.000 C). Is this a limitation of the particular Service Process, the IPMI itself or possibly the way the program is coded ?

Answer 1

Looking at the GetSensorReadingRsp message definition in the python-ipmi library, the actual reading value is defined as UnsignedInt. This corresponds with the IPMIv 2.0 spec, notably section 35.14 Get Sensor Reading Command which says the actual reading is stored in a single byte.