Chapter 6
Ladder Programming Examples
6–7
The RTD module was designed to interface directly to the SLC 5/02, SLC
5/03, SLC 5/04 and SLC 5/05 PID instruction without the need for an
intermediate scale operation. Use RTD channel data as the process variable
in the PID instruction.
To program this application, proceed as follows:
1. Select 100
Ω
Platinum RTD,
α
= 0.003916, as the input type by setting bit
0 = 0, bit 1 = 0, bit 2 = 1 and bit 3 = 0 in the configuration word.
2. Select scaled–for–PID as the data type by setting bit 4 = 0 and bit 5 = 1 in
the configuration word.
!
ATTENTION: When using the module’s scaled–for–PID data
format with the SLC PID function, ensure that the PID
instruction parameters Maximum Scaled S
max
(word 7)
and
Minimum Scaled S
min
(word 8) match the module’s minimum and
maximum scaled range, in engineering units, (e.g., –200
°
C to
850
°
C) for that channel. This allows you to accurately enter the
setpoint in engineering units (
°
C,
°
F)
Figure 6.7
Programming for PID Application
] [
MOVE
Source
N10:0
Dest
O:3.0
First Pass Bit
S:1
15
Rung 2:0
MOV
Initialize NR4 Channel 0
11
Rung 2:1
Channel 0
Status
] [
I:3.4
PID
PID
Control Block
N11:0
Process Variable
I:3.0
Control Variable
N11:23
Control Block Length
23
Entering address N11:0 allocates elements N11:0 to N11:22 for required
Control Block file length of 23 words. The Process Variable is address
I:3.0, which stores the value of input data word 0 (channel 0). Output of
the PID instruction is stored at address N11:23 (Control Variable
address).
Interfacing to the PID
Instruction
Содержание SLC 500 1746-NR4
Страница 1: ...User Manual SLC 500t RTD Resistance Input Module Cat No 1746 NR4 Allen Bradley AB Spares ...
Страница 15: ...Preface P 8 Notes AB Spares ...
Страница 37: ...Chapter 2 Quick Start 2 12 Notes AB Spares ...
Страница 63: ...Chapter 4 Preliminary Operating Considerations 4 12 Notes AB Spares ...
Страница 87: ...Chapter 5 Channel Configuration Data and Status 5 24 Notes AB Spares ...
Страница 107: ...Chapter 7 Module Diagnostics and Troubleshooting 7 8 Notes AB Spares ...
Страница 117: ...Chapter 8 Application Examples 8 10 Notes AB Spares ...
Страница 123: ...Appendix A Specifications A 6 Notes AB Spares ...
Страница 125: ...Appendix B RTD Standards B 2 Notes AB Spares ...