Campbell Manufacturing CR10 Coeff, Value, Param, Param, Transducer Instruction, Paroscientific "T" Series Pressure, TABLE 7.17-3Coefficient Entry Format for

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

Time out calculations using a recommended 9000 and 5000 cycles for temperature and pressure at the maximum frequency are shown below.

Time out for temperature: 6, 5.22 = (5.8*10-6)(9000/0.01)

Time out for pressure: 16,

15.5 = (3.1*10-5)(5000/0.01)

If the time out expires before the requested number of cycles are read, -99999 is stored in the input location (Parameter 6). After reading the correct number of cycles, program execution advances to the next instruction; the time out may be over estimated without losing execution speed.

CONVERTING MICROSECONDS TO °C AND PSI

The temperature and pressure in microseconds are converted to °C and psi according to the following relationships provided by Paroscientific.

Pressure (psi) =

C * (1 T02/Tau2) * (1 (D * (1 - T02/Tau2)))

Temperature (°C) = Y1U + Y2U2 + Y3U3

where, C = C1 + C2U + C3U2 (psi),

T0 = T1 + T2U + T3U2 + T4U3 + T5U4 (microsecond),

D= D1 + D2U (microsecond), U = U(t) U0 (microsecond),

Tau = measured pressure (microsecond), U(t) = measured temperature (microsecond).

Values for the calibration coefficients (U0, Y1,

Y2, Y3, C1, C2, C3, D1, D2, T1, T2, T3, T4, T5) are provided by Paroscientific.

ENTERING THE COEFFICIENTS

Coefficients are entered using CR10 Instruction 30 or 64. A calibration sheet from Paroscientific which accompanies the transducer lists the 14 coefficients. Table 7.17- 3 shows the correct format for entering the coefficients. The coefficients shown are for transducer Serial Number 30135. Your coefficients will be different.

TABLE 7.17-3 Coefficient Entry Format forParoscientific "T" Series PressureTransducer Instruction 30

Coeff.		Value	Param. 1	Param.
2
U0		5.860253	5.8603	0.0
Y1		-3970.348	-3970.3	0.0
Y2		-7114.265	-7114.3	0.0
Y3	102779.1		102.78	3.0*
C1		70.29398	70.294	0.0
C2		6.610141	6.6101	0.0
C3		-119.2867	-119.29	0.0
D1		0.0308837	30.884	-3.0*
D2		0.0	0.0	0.0
T1		26.33703	26.337	0.0
T2		0.8516985	0.85170	0.0
T3		21.80118	21.801	0.0
T4		0.0	0.0	0.0
T5		0.0	0.0	0.0

*Y3 and D1 are the only coefficients with a nonzero exponent.

Only the first 5 digits of each 7 digit coefficient are entered in the datalogger. The maximum error that occurs due to using five digit coefficients is 0.001 psi throughout a 15 psi range at any temperature between -30 and +60°C. The maximum error in temperature calculations is 0.2°C over the same temperature range.

CONNECTIONS

Figure 7.17-1 details the components required for connecting the transducer to the CR10. The user supplied components are commonly available at commercial electronic stores.

PROGRAM EXAMPLE

The program may be divided into the following 7 steps.

1.Load the coefficients into input locations (Subroutine 1).

2.Measure the temperature and pressure.

3.Compute U.

4.Compute temperature, °C.

5.Compute T0, T02, Tau2, and 1-T02/Tau2.

6.Compute D.

7.Compute C.

8.Compute pressure (psi.)

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