Campbell Scientific CR10X CR10X Measurement and Control System - Page 107

To 20 Ma Sensor Using, Curs100 Terminal Input, Module

Page 107 highlights

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES ;Find Temperature and Pressure. ; 04: Paroscientific (P64) 1: 1 Loc [ Temp_us ] 2: 19 Loc [ Temp_C ] * Table 3 Subroutines 01: Beginning of Subroutine (P85) 1: 1 Subroutine 1 02: Bulk Load (P65) 1: 5.8603 F 2: -3970.3 F 3: -7114.3 F 4: 102.78 F 5: 70.294 F 6: 6.6101 F 7: -119.29 F 8: 30.884 F 9: 3 Loc [ U0 ] 03: Bulk Load (P65) 1: 0 F 2: 26.337 F 3: .85170 F 4: 21.801 F 5: 0 F 6: 0 F 7: 1 F 8: 0 F 9: 11 Loc [ D2 ] 04: End (P95) End Program INPUT LOCATION LABELS: 1 Temp_us 2 Press_us 3 U0 4 Y1 5 Y2 6 Y3 7 C1 8 C2 9 C3 10 D1 11 D2 12 T1 13 T2 14 T3 15 T4 16 T5 17 Comp_Chk 18 plce_hold 19 Temp_C 20 Press_psi 21 Signature 7.18 4 TO 20 MA SENSOR USING CURS100 TERMINAL INPUT MODULE A dew point sensor has a 4 to 20 mA output over the dew point temperature range of -40° to +70°C. The dew point sensor output may be measured by the CR10X using the CUS100 Terminal Input Module (TIM). The CUS100 uses a 100 Ω, ± 0.01 % resistor to convert the 4 to 20 mA range to 400 to 2000 mV. The millivolt range was found using the relationship V = IR, where V is voltage, I is current, and R is resistance, e.g. the voltage at -40°C is given by V = 4 mA ∗ 100 Ω = 400 mV. The dew point sensor is measured with Instruction 2 (Volt Diff). The multiplier for dew point temperature is found with the following relationship [70°C (-40°C)] / [2000 mV - 400 mV] = 0.06875°C/mV. The offset is found by taking the linear relationship °C = mV ∗ Mult + Offset and solving for the Offset. At -40°C the voltage is 400 mV, thus the Offset = -40 - [400 mV ∗ 0.06875°C/mV] = -67.5°C. CONNECTIONS The dew point sensor is measured with a differential voltage measurement on differential analog input 4. The CURS100 TIM and dew point sensor are wired to the CR10X wiring panel as shown in Figure 7.18-1. PROGRAM 01: Volt (Diff) (P2) 1: 1 Reps 2: 25 ±2500 mV 60 Hz Rejection Range 3: 4 DIFF Channel 4: 1 Loc [ Dew_Pnt_C ] 5: .06875 Mult 6: -67.5 Offset INPUT LOCATIONS 1 Dew_Pnt_C 7-23

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SECTION 7.
MEASUREMENT PROGRAMMING EXAMPLES
7-23
;Find Temperature and Pressure.
;
04:
Paroscientific (P64)
1:
1
Loc [ Temp_us
]
2:
19
Loc [ Temp_C
]
*
Table 3 Subroutines
01:
Beginning of Subroutine (P85)
1:
1
Subroutine 1
02:
Bulk Load (P65)
1:
5.8603
F
2: -3970.3
F
3: -7114.3
F
4:
102.78
F
5:
70.294
F
6:
6.6101
F
7:
-119.29
F
8:
30.884
F
9:
3
Loc [ U0
]
03:
Bulk Load (P65)
1:
0
F
2:
26.337
F
3:
.85170 F
4:
21.801
F
5:
0
F
6:
0
F
7:
1
F
8:
0
F
9:
11
Loc [ D2
]
04:
End (P95)
End Program
INPUT LOCATION LABELS:
1 Temp_us
12 T1
2 Press_us
13 T2
3 U0
14 T3
4 Y1
15 T4
5 Y2
16 T5
6 Y3
17 Comp_Chk
7 C1
18 plce_hold
8 C2
19 Temp_C
9 C3
20 Press_psi
10 D1
21 Signature
11 D2
7.18
4 TO 20 MA SENSOR USING
CURS100 TERMINAL INPUT
MODULE
A dew point sensor has a 4 to 20 mA output
over the dew point temperature range of -40
°
to
+70
°
C.
The dew point sensor output may be
measured by the CR10X using the CUS100
Terminal Input Module (TIM).
The CUS100
uses a 100
,
±
0.01 % resistor to convert the 4
to 20 mA range to 400 to 2000 mV.
The
millivolt range was found using the relationship
V = IR, where V is voltage, I is current, and R is
resistance, e.g. the voltage at -40°C is given by
V = 4 mA
100
= 400 mV.
The dew point
sensor is measured with Instruction 2 (Volt Diff).
The multiplier for dew point temperature is
found with the following relationship [70°C -
(-40°C)] / [2000 mV - 400 mV] = 0.06875°C/mV.
The offset is found by taking the linear
relationship °C = mV
Mult + Offset and solving
for the Offset.
At -40°C the voltage is 400 mV,
thus the Offset =
-40 - [400 mV
0.06875°C/mV] = -67.5°C.
CONNECTIONS
The dew point sensor is measured with a
differential voltage measurement on differential
analog input 4.
The CURS100 TIM and dew
point sensor are wired to the CR10X wiring
panel as shown in Figure 7.18-1.
PROGRAM
01:
Volt (Diff) (P2)
1:
1
Reps
2:
25
±
2500 mV 60 Hz Rejection
Range
3:
4
DIFF Channel
4:
1
Loc [ Dew_Pnt_C ]
5:
.06875 Mult
6: -67.5
Offset
INPUT LOCATIONS
1 Dew_Pnt_C