Chapter 5
Channel Configuration, Data, and Status
5–8
Scaling Examples
The following examples are using the default scaling ranges:
Scaled–for–PID to Engineering Units
Equation:
Engr Units Equivalent = S
LOW
+ [ (S
HIGH
– S
LOW
) x (Scaled–for–PID value displayed / 16383) ]
Assume that the input type is an RTD, Platinum
(
200
W
,
a =
0.00385
°
C
,
range
=
–200
°
C
to +850
°
C
)
, scaled–for–PID display type. Channel data = 3421.
Want to calculate
°
C equivalent..
From Channel Data Word Format ( Table 5.C through Table 5.H), S
LOW
= –200
°
C and S
HIGH
= 850
°
C.
Solution:
Engr Units Equivalent = –200
°
C + [ (850
°
C – (–200
°
C) ) x (3421 / 16383) ] = 19.25
°
C.
Engineering Units to Scaled–for–PID
Equation:
Scaled–for–PID Equivalent = 16383 x [ (Engineering Units desired – S
LOW
) / ( S
HIGH
– S
LOW
) ]
Assume that the input type is an RTD, Platinum
(
200
W
,
a =
0.00385
°
C
,
range
=
–200
°
C
to +850
°
C
)
, scaled–for–PID display type. Desired channel temp. = 344
°
C.
Want to calculate Scaled–for–PID equivalent.
From Channel Data Word Format ( Table 5.C through Table 5.H), S
LOW
= –200
°
C and S
HIGH
= 850
°
C.
Solution:
Scaled–for–PID Equivalent = 16383 x [ (344
°
C – (–200
°
C) ) / ( 850
°
C – (–200
°
C ) ) ] = 8488.
Proportional Counts to Engineering Units
Equation:
Engr Units Equivalent = S
LOW
+ { (S
HIGH
– S
LOW
) x [ ( Proportional Counts value dis 32768) / 65536 ] }
Assume that input type is a potentiometer (1000
W,
range = 0
to 1000
W)
, proportional counts display
type. Channel data = 21567.
Want to calculate ohms equivalent.
From Channel Data Word Format ( Table 5.C through Table 5.H), S
LOW
= 0
W
and S
HIGH
= 1000
W
.
Solution:
Engr Units Equivalent = 0
W
+ { [1000
W
– (0
W
) ] x [ ( 21567 + 32768) / 65536 ] } = 829
W.
Engineering Units to Proportional Counts
Equation:
Proportional Counts Equivalent = { 65536 x [ ( Engineering Units desired – S
LOW
)
/ ( S
HIGH
– S
LOW
) ] } – 32768
Assume that input type is a potentiometer (3000
W,
range = 0
to 3000
W)
, proportional counts display
type. Desired channel resistance value = 1809
Ω
. Want to calculate Proportional Counts equivalent.
From Channel Data Word Format (Table 5.C through Table 5.H), S
LOW
= 0
W
and S
HIGH
= 3000
W
.
Solution:
Proportional Counts Equivalent = { 65536 x [ (1809
Ω
– (0
W
)
)
/ (3000
W
– (0
W
) ) ] } – 32768 = 6750.
AB Spares
Summary of Contents for SLC 500 1746-NR4
Page 1: ...User Manual SLC 500t RTD Resistance Input Module Cat No 1746 NR4 Allen Bradley AB Spares ...
Page 15: ...Preface P 8 Notes AB Spares ...
Page 37: ...Chapter 2 Quick Start 2 12 Notes AB Spares ...
Page 63: ...Chapter 4 Preliminary Operating Considerations 4 12 Notes AB Spares ...
Page 87: ...Chapter 5 Channel Configuration Data and Status 5 24 Notes AB Spares ...
Page 107: ...Chapter 7 Module Diagnostics and Troubleshooting 7 8 Notes AB Spares ...
Page 117: ...Chapter 8 Application Examples 8 10 Notes AB Spares ...
Page 123: ...Appendix A Specifications A 6 Notes AB Spares ...
Page 125: ...Appendix B RTD Standards B 2 Notes AB Spares ...
