Warning notices are used to emphasize that improper operation may cause severe personal injury or death.
Caution notices are used where inattention might cause personal injuryor damage to equipment.
SAFETY PRECAUTIONS
• Read this user’s manual to make sure of correct operation before starting installation, wiring, operation,
maintenance, and inspection of the FC5A series MicroSmart PID modules.
•All MicroSmart modules are manufactured under IDEC’s rigorous quality control system, but users must add a
backup or failsafe provision to the control system using the MicroSmart in applications where heavy damage or
personal injury may be caused in case the MicroSmart should fail.
•In this user’s manual, safety precautions are categorized in order of importance from Warning to Caution.
Warning
• Turn off the power to the MicroSmart before starting installation, removal, wiring, maintenance, and inspection of
the MicroSmart. Failure to turn power off may cause electrical shocks or fire hazard.
• Special expertise is required to install, wire, program, and operate the MicroSmart. People without such expertise
must not use the MicroSmart.
• Emergency stop and interlocking circuits must be configured outside the MicroSmart. If such a circuit is
configured inside the MicroSmart, failure of the MicroSmart may cause a malfunction of the control system,
damage, or accidents.
• Install the MicroSmart according to the instructions described in this user’s manual. Improper installation will
result in disattachment, failure, or malfunction of the MicroSmart.
Caution
• The MicroSmartis designed for installation in a cabinet. Do not install the MicroSmart outside a cabinet.
• Install the MicroSmartin environments described in this user’s manual. If the MicroSmart is used in places where
the MicroSmart is subjected to high-temperature, high-humidity, condensation, corrosive gases, excessive
vibrations, and excessive shocks, then electrical shocks, fire hazard, or malfunction will result.
• The environment for using the MicroSmart is “Pollution degree 2.” Use the MicroSmartin environments of pollution
degree 2 (according to IEC 60664-1).
• Prevent the MicroSmart from being dropped while moving or transporting the MicroSmart, otherwise damage or
malfunction of the MicroSmart will result.
• Prevent metal fragments and pieces of wire from dropping inside the MicroSmart housing. Put a cover on the
MicroSmart modules during installation and wiring. Ingress of such fragments and chips may cause fire hazard,
damage, or malfunction.
• Use a power supply matching the rated value. Use of an incorrect power supply may cause fire hazard.
• Use an IEC 60127-approved fuse on the power line outside the MicroSmart. This is required when equipment
containing the MicroSmart is destined for Europe.
• Use an IEC 60127-approved fuse on the output circuit. This is required when equipment containing the
MicroSmart is destined for Europe.
FC5A MicroSmart PID Module User’s Manual FC9Y-B1283 i
• Use an EU-approved circuit breaker. This is required when equipment containing the MicroSmart is destined for
Europe.
• Make sure of safety before starting and stopping the MicroSmart or when operating the MicroSmart to force
outputs on or off. Incorrect operation on the MicroSmart may cause machine damage or accidents.
• If relays or transistors in the MicroSmart output modules should fail, outputs may remain on or off. For output signals
which may cause serious accidents, provide a monitor circuit outside the MicroSmart.
• Do not connect the ground wire directly to the MicroSmart. Connect a protective ground to the cabinet containing
the MicroSmart using an M4 or larger screw. This is required when equipment containing the MicroSmart is
destined for Europe.
• Do not disassemble, repair, or modify the MicroSmart modules.
• When disposing of the
MicroSmart
, do so as an industrial waste.
ii FC5A MicroSmart PID Module User’s Manual FC9Y-B1283
NOTICE
1. This publication is not to be, nor any parts of it, photocopied, reprinted, sold, transferred, or rented out without
the specific written permission and consent of IDEC.
2. The contents of this user’s manual are subject to change without notice.
3. Care has been taken to ensure that the contents of this user’s manual are correct, but if there are any doubts,
mistakes or questions, please inquire our sales department.
Analog modules, AS-Interface master module, PID module
Communication Expansion Modules
HMI base module, expansion RS232C communication module,
expansion RS485 communication module
Optional Modules
HMI module, Memory cartridge, Clock cartridge, RS232C communication
adapter, RS485 communication adapter
WindLDR
Application software [WindLDR]
IMPORTANT INFORMATION
Under no circumstances shall IDEC Corporation be held liable or responsible for indirect or consequential damages resulting
from the use of or the application of IDEC PLC components, individually or in combination with other equipment.
All persons using these components must be willing to accept responsibility for choosing the correct component to suit their
application and for choosing an application appropriate for the component, individually or in combination with other
equipment.
All diagrams and examples in this user’s manual are for illustrative purposes only. In no way does including these diagrams
and examples in this manual constitute a guarantee as to their suitability for any specific application. To test and approve all
programs, prior to installation, is the responsibility of the end user.
The PID modules is used by connecting to the FC5A series CPU module.
Use this product after thoroughly understanding the specifications of the FC5A
series CPU module.
ABOUT THIS MANUAL
Thank you for purchasing FC5A series MicroSmart PID Module. This user’s manual primarily describes system
configuration, specifications, installation, programming, application examples, and trouble shooting of the PID
module. Read this user’s manual to ensure the correct understanding of the entire functions of the PID module.
MicroSmart Modules
Caution
FC5A MicroSmart PID Module User’s Manual FC9Y-B1283 iii
REVISION HISTORY
Date
Manual No.
Description
March, 2011
FC9Y-B1283-0
First print
Revision history of this user’s manual is described here.
iv FC5A MicroSmart PID Module User’s Manual FC9Y-B1283
Type No.
Manual Name
Description
FC9Y‐B1283
FC5A Series
PID Module
User's Manual
(this manual)
Describes PID Module specifications and functions.
FC9Y‐B1268
FC5A Series
MicroSmart Pentra
User's Manual
Basic Volume
Describes module specifications, installation instructions, wiring instructions,
basic operation, special function, device addresses, instruction list, basic
instructions, analog modules, user communication, data link communication,
Modbus ASCII/RTU communication, and troubleshooting.
FC9Y‐B1273
FC5A Series
MicroSmart Pentra
User's Manual
Advanced Volume
Describes instruction list, move instructions, data comparison instructions,
binary arithmetic instructions, boolean computation instructions, shift/rotate
instructions, data conversion instructions, week programmer instructions,
interface instructions, program branching instructions, refresh instructions,
interrupt control instructions, coordinate conversion instructions, average
instructions, pulse output instructions, PID instructions, dual/teaching timer
instructions, intelligent module access instructions, trigonometric function
instructions, logarithm/power instructions, file data processing instructions, clock
instructions, computer link communication, modem communication, Modbus
TCP communication, expansion RS232C/RS485 communication modules, and
AS‐Interface master modules.
FC9Y‐B1278
FC5A Series
MicroSmart Pentra
User's Manual
Web Server CPU
Module Volume
Describes FC5A Slim Type Web Server CPU Module specifications and
functions.
RELATED MANUALS
The following manuals related to the FC5A series MicroSmart are available. Refer to them in conjunction with this
manual.
FC5A MicroSmart PID Module User’s Manual FC9Y-B1283 v
vi FC5A MicroSmart PID Module User’s Manual FC9Y-B1283
TABLE OF CONTENTS
CHAPTER 1: GENERAL INFORMATION ...................................................................................... 1-1
About the PID Modules .................................................................................................................................... 1-1
Quantity of Applicable PID modules ................................................................................................................ 1-1
Applicable CPU and WindLDR version ........................................................................................................... 1-2
Confirming System Program Version .............................................................................................................. 1-2
Type of Protection ............................................................................................................................................ 3-5
Power Supply for PID Modules ....................................................................................................................... 3-6
CHAPTER 4: PID MODULE MAIN FUNCTIONS .......................................................................... 4-1
Temperature Control Using the PID Module .................................................................................................... 4-1
Fixed Value Control ......................................................................................................................................... 4-3
Program Control .............................................................................................................................................. 4-9
Heating/Cooling Control ................................................................................................................................ 4-14
Difference Input Control ................................................................................................................................. 4-14
Cascade Control ............................................................................................................................................ 4-15
CHAPTER 5: DEVICE ALLOCATION OF PID MODULE ................................................................ 5-1
Device Allocation of PID Module ..................................................................................................................... 5-1
Program Size ................................................................................................................................................... 5-2
Control Register ............................................................................................................................................... 5-2
Control Relay ................................................................................................................................................... 5-3
Data Register Allocation - Block 0 Read Only Parameters ............................................................................. 5-7
Data Register Allocation - Block 1 Write Only Parameters............................................................................ 5-10
Application Example 1 ..................................................................................................................................... 7-1
Application Example 2 ..................................................................................................................................... 7-8
Application Example 3 ................................................................................................................................... 7-15
Factory Default Settings of the PID Module .................................................................................................... 9-9
viii FC5A MicroSmart PID Module User’s Manual FC9Y-B1283
GENERAL INFORMATION
Module Type
I/O Points
I/O Signal
Type No.
Relay Output
2 inputs
Thermocouple [K, J, R, S, B, E, T, N, PL- II, C (W/Re5-26)]
Resistance thermometer (Pt100, JPt100)
Voltage (0 to 1V DC, 0 to 5V DC, 1 to 5V DC, 0 to 10V DC)
Current (0 to 20mA DC, 4 to 20mA DC)
FC5A-F2MR2
2 outputs
Relay contact
Non-Contact Voltage
(for SSR drive)/
Current Output
2 inputs
Thermocouple [K, J, R, S, B, E, T, N, PL- II, C (W/Re5-26)]
Resistance thermometer (Pt100, JPt100)
Voltage (0 to 1V DC, 0 to 5V DC, 1 to 5V DC, 0 to 10V DC)
Current (0 to 20mA DC, 4 to 20mA DC)
This chapter describes general information and specifications of the FC5A series PID modules. Make effective
use of the PID modules after reading and understanding thoroughly functions and characteristics.
About the PID Modules
The PID module performs control actions to eliminate the deviation between the set point (SP) and process
variable (PV). The PID module, which is an expansion module, is required to connect to the FC5A series CPU
for use. Depending on the difference of output specifications, the PID modules are categorized into two types,
and can be used by connecting to a FC5A slim type CPU, or 24-I/O all-in-one type CPU (except 12V DC CPU).
The input channel can accept voltage, current, thermocouple or resistance thermometer signals. The output
channel generates relay output, non-contact voltage (for SSR drive), or current signals.
To configure the PID modules, the Expansion Modules Configuration dialog box in WindLDR is used.
The following table shows the PID module type numbers.
PID Module Type Numbers
Quantity of Applicable PID modules
The maximum number of PID modules that can be connected to the MicroSmart CPU differs depending on the
CPU type. The following table shows the maximum number of the PID modules.
(2) Power LED (PWR)
(3) Control Output LED (OUT0, OUT1)
(4) Event Output LED (EVT0, EVT1)
(5) Auto-tuning (AT)/Auto-reset LED (AT0, AT1)
(6) Manual Mode LED (MT0, MT1)
(7) Fixed Value Control Mode/Program
ON : Control output is turned on.
OFF : Control output is turned off.
Flashes : When current output is used, the LED flashes in a cycle of 125 ms
according to the duty ratio of the output manipulated variable (MV).
When output manipulated variable (MV) is 20%, the LED turns on for
25 ms and off for 100 ms continuously.
(4) Event Output LED (EVT0, EVT1)
ON : Any alarm out of alarm 1 to alarm 8, loop break alarm is triggered.
OFF : None of the alarms is triggered.
(5) Auto-tuning (AT)/Auto-reset LED (AT0, AT1)
Flashes : Auto-tuning (AT) or auto-reset is performing.
OFF : Auto-tuning (AT) or auto-reset is stopped.
(6) Manual Mode LED (MT0, MT1)
ON : Manual mode
OFF : Auto mode
(7) Fixed Value Control Mode/Program Control Mode LED (F/P0, F/P1)
ON : Program control mode
OFF : Fixed value control mode
(8) Program Control RUN/HOLD LED (R/H0, R/H1)
ON : Program control is performing, or while in fixed value control enabled.
Flashes : Program control is held, or power is restored.
OFF : Program control is stopped, or while in fixed value control disabled.
(9) External SP Enable/Disable LED (R/L)
ON : External SP input is enabled.
OFF : External SP input is disabled.
(10) Terminal No. Indicates terminal numbers.
(11) Cable Terminal Spring clamp type terminal for connecting a cable.
(12) Expansion Connector Connects to the CPU module and other expansion modules.
External resistance: 100Ω maximum
However, B input, External resistance: 40Ω
maximum
Resistance
Thermometer
Pt100, JPt100, 3-wire type
Allowable conductor resistance (per wire):
10Ω maximum
Sensor (detection) current: 0.2A
Current
0 to 20mA DC, 4 to 20mA DC
Input impedance: 50Ω
Maximum permanent allowed overload (No
damage): 50mA maximum
Voltage
0 to 1V DC
Input impedance: 1MΩ minimum
Maximum permanent allowed overload (No
damage): 5V DC maximum
Allowable output impedance: 2kΩ maximum
0 to 5V DC, 1 to 5V DC, 0 to 10V DC
Input impedance: 100kΩ minimum
Maximum permanent allowed overload (No
damage): 15V DC maximum
Allowable output impedance: 100Ω maximum
±0.2% of full scale or ±2°C (4°F),
whichever is greater
However, R, S inputs, 0 to 200°C (0 to 400°F):
±6°C (12°F)
B input, 0 to 300°C (0 to 600°F): Accuracy is
not guaranteed.
K, J, E, T, N inputs, Less than 0°C (32°F):
±0.4% of full scale
Resistance
Thermometer
±0.1% of full scale or ±1°C (2°F), whichever is
greater
Voltage, Current
±0.2% of full scale
Input Accuracy (at 0 to 55°C)
Thermocouple
±0.7% of full scale
However, R, S input, 0 to 200°C (0 to 400°F):
±6°C (12°F)
B input, 0 to 300°C (0 to 600°F): Accuracy is
not guaranteed.
K, J, E, T, N inputs, Less than 0°C (32°F):
±0.9% of full scale
Resistance
Thermometer
±0.6% of full scale
Voltage, Current
±0.7% of full scale
Data Accuracy
Maximum error at 25°C±Minimum digital resolution of each input range
Photocoupler-isolated between input and internal circuit
Photocoupler-isolated between input and power circuit
Photocoupler-isolated between input and internal circuit
Photocoupler-isolated between output and internal circuit
Caution • Assemble the CPU module and PID modules before installing them on a DIN rail.
Otherwise, they may break.
• Do not lay out or wire the modules while power is supplied to them. Otherwise, they
may be damaged.
• When installing modules, follow the instructions described in the FC5A MicroSmart
user’s manual. If there are flaws in the installation, it may cause disattachment,
failure or malfunction.
Direct mounting strip
FC4A-PSP1P
3: INSTALLATION AND WIRING
This chapter describes how to install and wire the PID modules. For general methods and precautions for
installation and wiring of the PID modules, see chapter 3 in the FC5A MicroSmart user’s manual (FC9Y-B1268).
Be sure to use the PID modules properly after understanding installation and wiring thoroughly.
Mounting Hole Layout for Direct Mounting on Panel Surface
To mount the PID module on a panel surface,
use the direct mounting strip and two M4 screws
(6 or 8 mm long).
For details about the direct mounting strip, see the
FC5A MicroSmart user’s manual (FC9Y-B1268).
Separate the I/O lines
from the power line
as much as possible.
DC : Voltage/Current
RTD : Resistance thermometer
TC : Thermocouple
: Load
: Analog current input instrument
: Fuse
+
-
NC
+
NC
-
+
-
NC
-
NC-
NCNCNC-
L
L
+
FG
NC
B
-
+
-
TC
A
B
B
RTD
+
-
+
-
+
-
+
-
TC
A
B
B
RTD
+
-
+
-
+
-
-
-
NC
NC
+
”
+
’
+
-
NC
-
B
’
A
B
+
”
+
’
+
-B
’
A
DCDCDC
DCDCDC
24V DC
IN0
IN1
OUT1
OUT0
Channel
Terminal
No.
Terminal
No.
Channel
L
0 to 5V
4 to 20mA
1 to 5V
0 to 10V
0 to 20mA
0 to 1V
0 to 5V
4 to 20mA
1 to 5V
0 to 10V
0 to 20mA
0 to 1V
Fuse (50V-1.2A)
Power Supply for PID Modules
When supplying power to the PID modules, take the following into consideration.
Using the same power supply for the MicroSmart CPU and the PID module is recommended to suppress the
influence of noise. If the same power source is used for the PID module and MicroSmart CPU module, after the
MicroSmart CPU is started to run, the PID module performs initialization for a maximum of 5 seconds. During
this period, each parameter has an indefinite value. Design the user program to make sure that each parameter
is referred in the CPU module after the PID module operating status is changed to 0001h (Normal operation).
Wiring of Power Line and I/O Lines for the PID Module
Separate the I/O lines, particularly resistance thermometers, from the power line as much as possible to
suppress the influence of noise.
Control Target, such
as Electric Furnace
or Constant
Temperature Oven.
Heater
C. Actuator
200V AC
Temperature
Set point (SP)
Time
Temperature
Set point (SP) B
Time
Set point (SP) A
4: PID MODULE MAIN FUNCTIONS
This chapter describes the temperature control, fixed value control, auto-tuning (AT), program control,
heating/cooling control, difference input control, and cascade control of the PID module.
Temperature Control Using the PID Module
Temperature Control Configuration Example Using the PID Module
A. Sensor
Measures temperature of the control target. Thermocouple, resistance thermometer, voltage input,
or current input can be used as the sensor.
B. PID module
Receives the temperature measured by the sensor as the process variable (PV), and calculates the
output manipulated variable (MV) so that temperature difference (deviation) between the process
variable (PV) and the set point (SP) can be eliminated. The output manipulated variable (MV) is
outputted to the actuator as a control signal. Relay output, non-contact voltage output, or current
output can be used as the control signal.
C. Actuator
Receives a control signal from the PID module and turns on the load power supply to the heater.
Electromagnetic switches, SSR, or power controllers can be used as the actuator.
Optimal Temperature Control
The ideal temperature control, as shown in Figure 1, is to control the temperature to correspond with the
set point (SP) regardless of any disturbances. There should be no overshoot or response delay of time
until the temperature reaches the set point (SP).
Figure 1. Ideal Temperature Control Figure 2. Optimal Temperature Control
In reality, the ideal temperature control shown in Figure 1 on the previous page is almost impossible to
achieve due to a number of complicated factors such as thermal capacity, static characteristics, dynamic
characteristics and disturbances.
Figure 2 is regarded as an optimal temperature control result. Depending on the usage and objective, for
some temperature control applications, suppression of overshoot is required even if the temperature
rises very slowly as shown in Figure 3. For some temperature control applications, it is necessary to
stabilize the temperature as quickly as possible by raising the temperature rapidly even if overshoot is
generated as shown in Figure 4. In general, however, Figure 2 is regarded as an optimal temperature
control. The PID module is designed to raise the process variable (PV) to the set point (SP) as quickly as
possible in order to stabilize the process variable (PV) at the set point (SP) so as to perform the optimal
temperature control. If the temperature fluctuates due to sudden disturbances, the PID module responds
to the fluctuation with speedy response in the shortest possible time and performs quick control to
stabilize the temperature.
Figure 3. Stable but slow temperature rise control
Figure 4. The temperature rises rapidly; however, the control stabilizes after overshoot and undershoot.
Characteristics of the Control Target
To perform optimal temperature control, it is necessary to have a good knowledge of the thermal
characteristics of the PID module, sensors, actuators as well as control targets. For example, the PID
module controls a constant temperature oven and its temperature can rise up to 100°C. Even if the set
point (SP) of the PID modules is configured as 200°C, the temperature of the constant temperature oven
rise only up to 100 °C due to its static characteristic.
The characteristic of the control target is determined by the combination of the following 4 factors.
1. Thermal capacity:
This represents how the target is easily heated, and has a relation with the volume size of the control
target.
2. Static characteristic:
This represents the capability of heating, and is determined by the size of the heater capacity.
3. Dynamic characteristic:
This represents the rising characteristic (transitional response) during initial heating. This is a
complicated process involving heater capacity, furnace capacity size and sensor location.
4. Disturbance:
Any change in control temperature causes disturbance. For example, the change of ambient
temperature or supply voltage can cause disturbance.
The PID module provides 2 control modes, one is the fixed value control and the other is the program control.
The fixed value control is a standard temperature control which performs to eliminate the deviation between
the single set point (SP) and process variable (PV). The program control allows you to define the set point
(SP) that changes as the time progresses so that the process variable (PV) can be controlled to match the set
point (SP) changing as the time progresses. For detail about the program control, see 4-9.
Control actions that can be used for fixed value control and program control are described below.
ON/OFF Control Action
In the ON/OFF control action, when the process variable (PV) is lower than the set point (SP), the control
output is turned on, and when the process variable (PV) exceeds the set point (SP), the control output is
turned off. Overshoot, undershoot, and hunting are generated. ON/OFF control is suitable for processes
which do not require accuracy.
If the proportional band or proportional gain of the PID module parameter is set to 0, the control action
becomes ON/OFF control.
Overshoot, Undershoot
As the temperature of the control target
rises as shown in the figure on the right,
the process variable (PV) sometimes
exceeds the set point (SP) greatly.
This is called overshoot. If the process
variable (PV) drops below the set point
(SP), this is called undershoot.
Hunting
The control result oscillates as shown
in the figure on the right. This is the
the hunting.
P Control Action (Proportional Action)
P control action outputs the manipulated variable (MV) in proportion to the deviation between the process
variable (PV) and the set point (SP) within the proportional band. The control output is ON until the
process variable (PV) reaches the point A that is determined by the proportional band. If the process
variable (PV) exceeds the point A (enters the proportional band), the control output starts turn on/off
according to the control period and the manipulated variable (MV). If the process variable (PV) exceeds
the set point (SP), the control output is completely turned off. While the process variable (PV) rises from
the point A to the set point (SP), the control output ON time decreases and the control output OFF time
increases. Compared to ON/OFF control action, there is no overshoot in P control action, and hunting
becomes less frequent; however, the offset is generated. The P control action is suitable for processes
such as gas pressure control or level control, in which there is no dead time.
If the integral time and derivative time of the PID module parameter are set to 0, the control action
becomes the P control action.
Proportional band area that
can be configured with reset
function.
Offset can be corrected within
±proportional band from the
set point (SP).
Output Manipulated Variable
A: 100%
B: 50%
C: 0%
Set Point (SP)
Temperature
Time
Proportional Band
Disturbance
• If the proportional band is narrowed (Proportional gain is made larger)
Because the control output starts turning on/off at around the set point (SP), the time until the process
variable (PV) reaches the set point (SP) is shortened, and the offset is small; however, hunting is
frequent. If the proportional band is greatly narrowed, the control action becomes similar to the ON/OFF
control action.
• If the proportional band is broadened (Proportional gain is made smaller)
Because the control output starts turning on/off at the significantly low temperature from the set point
(SP), overshoot or hunting is reduced; however, it takes time for the process variable (PV) to reach to
the set point (SP), and the offset between the process variable (PV) and the set point (SP) becomes
broadened.
The offset caused by the P control action can be corrected by configuring the reset value. If the reset
value is configured, the proportional band range can be shifted as shown in the figure below. The reset
value can be automatically calculated by the auto-reset function.
PI Control Action (Proportional + Integral Action)
I (Integral) action automatically corrects the offset caused by P control action, and temperature control is
performed at the set point (SP). However, it takes time for the process variable (PV) to be stable if the
process variable (PV) is changed rapidly due to disturbance. PI control action is suitable for the
processes in which the temperature slowly changes.
If the derivative time of the PID module parameter is set to 0, the control action becomes the PI control
action.
• If the integral time is shortened too much, the integral action becomes strong. The offset can be
corrected in a shorter time; however, hunting with a long cycle may be caused.
• If the integral time is extended too much, the integral action becomes weak and it takes time to correct
PD Control Action (Proportional + Derivative Action)
Compared with P action, the response to rapid temperature change due to disturbance is faster, the
temperature control can be stabilized in a shorter time, and transitional response characteristic can be
improved in PD control action. PD control action is suitable for the processes in which the temperature
rapidly changes.
If the integral time of the PID module parameter is set to 0, the control action becomes the PD control
action.
• If the derivative time is shortened, the derivative action becomes weak. The response to the rapid
temperature change becomes slower. Because the action to suppress the rapid temperature rises
becomes weaker, the time for the process variable (PV) to reach the set point (SP) is shortened;
however, overshoot can occur.
• If the derivative time is extended, the derivative action becomes strong. The response to the rapid
temperature change becomes faster. Because the action to suppress the rapid temperature rises
becomes strong, the time for the process variable (PV) to reach the set point (SP) is extended; however,
overshoot can be decreased.
The offset caused by the PD control action can be corrected by configuring the reset value. The reset
value can be automatically calculated by the auto-reset function.
PID Control Action (Proportional + Integral + Derivative Action)
P action suppresses the overshoot and the hunting, I action corrects the offset, and D action corrects
rapid temperature change due to disturbance in shorter time. Thus, using PID control action, optimal
temperature control can be performed. The proportional band, integral time, derivative time, and ARW
can be automatically calculated by the auto-tuning (AT).
Caution • Perform auto-tuning (AT)/auto-reset during the trial run.
• If the auto-tuning (AT) is performed near the ambient temperature, sufficient
fluctuations cannot be given to the process, and auto-tuning (AT) may fail. In
such case, configure the P, I, D, and ARW values manually.
• Perform auto-reset when the process variable (PV) is stabilized within the
proportional band.
• Once auto-tuning (AT)/auto-reset is performed, it is unnecessary to perform
auto-tuning (AT)/auto-reset again as long as the process is unchanged.
• When voltage or current input is selected and the auto-tuning (AT) is performed,
fluctuations are given to the process at the set point (SP) regardless of AT bias.
• During program control, fluctuations are given to the process as soon as
auto-tuning (AT) is started.
Auto-Tuning (AT)/Auto-Reset
The optimal temperature control parameters differ depending on the characteristics of the process to control.
For PID control action, the proportional band, integral time, derivative time, and ARW are automatically
configured by performing auto-tuning (AT). For P control or PD control action, the reset value is automatically
configured by performing auto-reset.
Auto-tuning (AT)
In order to configure P (proportional band), I (integral time), D (derivative time), and ARW (Anti-Reset
Windup) automatically with optimal values, the auto-tuning (AT) can be performed. The auto-tuning (AT)
gives temperature fluctuation to the process to calculate those parameters. To perform an optimal
auto-tuning (AT), temperature fluctuation is given to the process when the process variable (PV) reaches
near the set point (SP). By setting the AT bias, the temperature to start giving fluctuation can be configured.
The relation between the set point (SP), AT bias, auto-tuning (AT) starting point, and fluctuation starting point
are shown below.
[Process variable (PV) ≤ Set point (SP) - AT bias value]
When AT bias is set to 20°C, the PID module starts giving the temperature fluctuation to the process at the
temperature 20°C lower from the set point (SP).
(1) Fluctuation period. PID parameters are
measured.
(2) PID parameters are calculated and auto
tuning (AT) is finished.
(3) Temperature is controlled with the PID
parameters configured with auto-tuning (AT).
(4) AT bias value (20°C)
▲ AT: Auto-tuning (AT) perform bit is turned on
[Set point (SP) - AT bias value < Process variable (PV) < Set point (SP) + AT bias value]
The PID module starts giving the temperature fluctuation to the process when the process variable (PV)
reaches the set point (SP).
(1) Fluctuation period. PID parameters are
measured.
(2) PID parameters are calculated and auto
tuning (AT) is finished.
(3) Temperature is controlled with the PID
parameters configured with auto-tuning (AT).
(4) AT bias value (20°C) ▲ AT: Auto-tuning (AT) perform bit is turned on
[Process variable (PV) ≥ Set point (SP) + AT bias value]
When AT bias is set to 20°C, the PID module starts giving the temperature fluctuation to the process at
the temperature 20°C higher from the set point (SP).
(1) Fluctuation period. PID parameters are
measured.
(2) PID parameters are calculated and auto
tuning (AT) is finished.
(3) Temperature is controlled with the PID
parameters configured with auto-tuning (AT).
(4) AT bias value (20°C) ▲ AT: Auto-tuning (AT) perform bit is turned on
Auto-reset
During the P control or PD control action, the deviation (offset) between the process variable (PV) and the
set point (SP) is generated when the process variable (PV) is stabilized. By performing auto-reset, the reset
value can automatically be calculated to correct the offset. It is required to perform auto-reset when the
process variable (PV) is stabilized within the proportional band. When the auto-reset is completed, the CPU
module automatically reads all parameters including the calculated reset value from the PID module and
stores those parameters in the data registers. It is unnecessary to perform the auto-reset again as long as
the process is unchanged.
When the proportional band (P) is set to 0 or 0.0, the reset value is cleared.
Auto-tuning (AT)/Auto-reset Perform/Cancel
The Auto-tuning (AT)/Auto-reset function can be performed or cancelled by turning on/off the operation
parameter bits allocated to each channel. For the operation parameter bits, see page 5-10.
Perform Auto-tuning (AT)
To perform auto-tuning (AT), turn on the control enable/disable bit (Bit0) and auto-tuning (AT)/auto-reset
bit (Bit1) of the operation parameter. P, I, D and ARW values will automatically be configured.
When auto-tuning (AT) is performed during the program control, P, I, D and ARW values of the current
step are configured. While auto-tuning (AT) is performed, the Auto-tuning (AT)/Auto-reset LED (AT0/AT1)
flashes.
When auto-tuning (AT) is completed, the operation parameter Bit1 is automatically turned off, and the
CPU module reads all parameters of the AT performed channel from the PID module and store those
parameters in the data registers. If any parameters in the data registers of the CPU module have been
changed but have not been written to the PID module, those parameters will be overwritten with the
parameters read from the PID module when auto-turning (AT) is finished.