Programming Electronic Instrumentation

Assignment 3. Due May 13

Refer to the handouts for the CR10 and 107 Temperature probe. The CR10 is a datalogger computer, which interrogates and archives information from a variety of sensors. The 107 Temperature probe is a basic thermistor that measures the resistance of an electric current and interprets the resistance in terms of temperature. Notice in Table 3 that the resistance is much higher for cold temperatures than warm temperatures.

Each student is to do this exercise individually so that everyone is familiar with the operation of the CR10 and temperature probe.

Begin by writing in the Wiring panel diagram for the CR10 the locations for the wires of the 107 probe as follows: (1) black lead in E1 (excitation channel 1) (2) red lead in 2H (channel 3) (3) purple lead in any of AG (alternate ground) and (4) clear lead in any G (ground).

Now attach the leads to each of the channels as detailed above. Be gentle and don't force any of the wires or screws.

The next step is to program the CR10 to query the sensor. Refer to the CR10 prompt sheet for further information. Type A to advance thru instructions; type B to see instrcutions already entered; type #D to delete command at P level; type D to get decimal point There is no need to type P, rather it indicates that you are at the appropriate point to enter a new instruction.

type *1 to begin entering commands

type 1 to indicate 1 second update for instructions

type P11 to indicate CR10 instruction 11

type 1 to indicate only 1 repetition (1 instrument)

type 3 to indicate voltage will be in channel 3

type 1 to indicate excitation originates in channel E1

type 1 to indicate output will be written into memory location 1

type 1 to indicate multiplier 1 (will be in celsius)

type 0 to indicate no offset

type P18 to indicate instruction to obtain minutes/seconds

type 0 to indicate seconds desired

type 0 to indicate no modulo division

type 2 to indicate put seconds in output location 2

type *0 to save instructions

type *6 to access output from sensor

Type A or B to advance or step back between temperature in output register 1 or time in seconds in output register 2.

Hold the sensor in your palm until it reaches a fairly steady body temperature. Then remove your hand from the sensor and record the temperature and time every few seconds until it reaches a fairly steady room temperature.

From your information collected, determine the response time of this sensor by determining the time that it takes to reach 36.8% of the equilibrium temperature. Plot on semilog paper, the ratio (T-Ta)/(T0-Ta) where Ta is the final air temperature and T0 is the original (body) temperature as a function of time, and T is the temperature at each time.