Automation Direct DL05 User Manual page 90

Setpoint V+02
PID Mode 2 Setting V+01
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2
0 0
Select data
0 1
format using
bits 0 and 1.
1 0
1 1
The data format determines the numerical interface between the PID loop and the PV sensor,
and the control output device. This selects the data format for both the SP and the PV.
Loop Mode
Loop Mode is a special feature that allows the PID loop controller to perform closed-loop
control while the CPU is in the Program Mode. Careful thought must be taken before using
this feature called Independent of CPU mode in the dialog. Before continuing with the PID
setup, a knowledge of the three PID loop modes will be helpful.
The DL05 provides the three standard control modes: Manual, Automatic, and Cascade. The
sources of the three basic variables SP, PV and control output are different for each mode.
In Manual Mode, the loop is not executing PID calculations (however, loop alarms are still
active). With regard to the loop table, the CPU stops writing values to location V+05 (control
output) for that loop. It is expected that an operator or other intelligent source is manually
controlling the output by observing the PV and writing data to the control output as
necessary to keep the process under control. The drawing below shows the equivalent
schematic diagram of manual mode operation.
Input from Operator
Loop
Calculation
In Automatic Mode, the loop operates normally and generates new control output values. It
calculates the PID equation and writes the result in location V+05 every sample period of that
loop. The equivalent schematic diagram is shown below.
Input from Operator
Loop
Calculation
Calculation
+
–
Process Variable V+03
1 0
Data formats
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3
= sign bit
Manual
Auto
Manual
Auto
DL05 Micro PLC User Manual, 6th Edition, Rev. A
Chapter 8: PID Loop Operation
Control Output V+05
Loop
LSB
2 1 0
12 bit unipolar 0 to 0FFF (0 to 4095)
0 to 0FFF, 8FFF to 8001
12 bit bipolar
(0 to 4095, *–4095 to 4095)
15 bit unipolar 0 to 32767
15 bit bipolar 0 to 7FFF, FFFF to 8001
(0 to 32767, *–32767 to 32767)
* Magnitude plus sign
Control Output V+05
Control Output V+05
1
2
3
4
5
6
7
8
9
10
11
12
13
14
A
B
C
D
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