EXTECH 96VTR

INSTRUCTION MANUAL
Model 96VTR
¼ DIN Process Controller
1. INTRODUCTION
The 96VTR is a microprocessor-based device which can compare a process input
(thermocouple, RTD, or analog input) to a user-programmable setpoint and adjust the
process (via relay or analog outputs), to bring the process to the desired setpoint. This ThreeMode PID controller offers:
‰
‰
‰
‰
‰
‰
‰
Simultaneous Process Value (PV) and Setpoint Value (SV) display
Automatic alarm functions (11 in all)
Autotuning automatically tailors the controller's response to a specific process
Security lock-out
Ramp-to-Setpoint and Soak functions
Input selectability
Optional RS-485 PC interface
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Ver. 2.0 11/99
2. SPECIFICATIONS
2.1 General Specifications
Display
LED Status Indicators
Display range (span)
Indicating Accuracy
Sampling Time
Memory
Meter Enclosure
Front Panel
Power Supply
Power Consumption
Insulation Resistance
Noise Rejection
Oper. Temp/Humidity
Storage Temperature
Dimensions (Cutout)
Dual 7-segment 4-digit LED Displays: Red (PV), Green (SV)
Control outputs (C1, C2), Alarm outputs (A1, A2), Autotune (AT),
o
o
Manual mode (MA), and temperature units C/ F
-1999 to 9999 counts max (Programmable; limited by the range
specified in Section 2.2 for each individual input type)
+0.2% Full Scale +1 digit
4 readings per second
Nonvolatile. Meter memorizes user configuration on power-down
ABS Plastic
Lexan (Drip and Dust Proof; IEC IP55, NEMA Equivalent)
85 to 260VAC 50/60 Hz (automatic switching)
6 Watts
>50M ohm
Common Mode: 110 dB typical; Normal Mode: 50 db typical
o
o
14 to 122 F (-10 to 50 C); 90% RH max.
o
o
-4 to 140 F (-20 to 60 C)
3.58 x 3.58" ±0.02" (91.0 x 91.0mm ±0.5mm)
2.2 Input Specifications
Thermocouple inputs
(Programmable)
RTD input
Current input
Voltage input
Thermocouple Ranges
Type K
Type J
Type B
Type T
Type E
Type R
Type S
Type N
RTD PT100 input ranges
Linear input range
Temperature Stability
Repeatability
Types: J, K, T, E, B, R, S, N; Cold Junction Compensation;
Thermocouple Break Protection: Upscale, Downscale
Lead Wire Effect: 0.015%/ohm (Input impedance: 10 megohm)
Pt 100 ohm (DIN, JIS);
RTD Break Protection: Upscale, Downscale;
Lead Wire Effect: 0.015%/ohm
(automatically compensates if one lead wire is < 5Ω)
4-20mA DC (27Ω input resistance)
1-5V DC
o
o
-58 to 2498 F (-50 to 1370 C)
o
o
-58 to 1830 F (-50 to 1000 C)
o
o
32 to 3272 F (0 to 1800 C)
o
o
-454 to 752 F (-270 to 400 C)
o
o
-58 to 1382 F (-50 to 750 C)
o
o
32 to 3182 F (0 to 1750 C)
o
o
32 to 3182 F (0 to 1750 C)
o
o
-58 to 2372 F (-50 to 1300 C)
o
o
-392 to 932 F (-200 to 500 C); DIN or JIS
-1999 to 9999 display span (for 4-20mA, 1-5V, or special input)
o
5uV/ C typical
o
o
0.83 C (Thermocouple); 0.2 C (RTD); 1 digit (Linear)
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2.3 Output Specifications
Control Output Relay 1 & 2
Optional Pulsed Outputs
Optional Analog Control Output
Alarm/Timer Types
Alarm Output Relays 1 and 2
Output Control Modes
Proportional Band
Integral Time
Derivative Time
Cycle Time
Anti-Reset Wind-Up
Manual Reset
Hysteresis
5A @ 110VAC; 3A @ 220VAC; SPDT (Resistive Load)
Note: Relay 1 is called the Primary Output and Relay 2 the
Secondary in this manual
24V DC (DC drive for SSR)
ON: 24V DC typical, 29V DC max.; OFF: 0.3V DC max
4-20mA DC; Load limit: 600Ω impedance max.
High/Low Deviation and Absolute Alarms w/deadband
adjust and Soak/Event ON/OFF Timers
5A @ 110VAC; 3A @ 220VAC, SPST (Resistive Load)
0.0 to 100.0% of Full Scale (Autotune)
0 to 3000 secs. (Autotune)
0 to 3000 secs. (Autotune)
1 to 100 secs. (0 sec for 4-20mA output)
Inhibits integral action outside of the Proportional Band
0 to 100% of Prop. Band
0.0 to 25.5% of Full Scale
3. MOUNTING AND WIRING
3.58" +0.02"
3.1 Prepare a 3.58 x 3.58" ±0.02" (91.0 x 91.0mm ±
0.5mm) panel cutout (refer to Fig.2). The panel
on which the controller will be mounted may be
up to 0.4" (10mm) thick.
3.2 Slide the meter into panel through the cutout.
3.3 Affix the mounting brackets to the top and
bottom of the meter and tighten the bracket
screws. Do not tighten the screws excessively.
3.4 Connect the power cord to the meter but do not
connect to power source.
3.5 Connect sensor input and control/alarm outputs.
3.6 Connect power to source.
Cut-Out
Dimensions
3.58"
+0.02"
Figure 2
Screw Terminals
RS-485 Connections
Wiring Notes:
AC: The AC supply terminals can
handle 85 to 260VAC 50/60Hz.
Control Output Relays: Terminals
14,15 and 16,17 (NO); Terminals
16,18 (NC).
TX/RX+
1
11
TX/RX-
2
12
+24VDC
3
13
0V
4
4-20
OUT
5
2-Wire RTD Inputs: Connect RTD
across terminals 9 and 10. Short
terminals 8 and 9.
8
18
9
19
7
+
Thermocouple
and Analog
inputs
4-Wire RTD Inputs: Connect in the
same fashion as a 3-wire and leave
the 4th RTD wire open.
10
4-20
OUT
Alarm 2
SPST N.O.
14
+15
Alarm Relays: Terminals 11, 12 and
12, 13 are N.O. when controller is
powered down AND when it's
powered-up in non-alarm condition.
6
Alarm 1
SPST N.O.
Output 2
Secondary N.O.
+16
Output 1
Primary N.O. or N.C
17
AC
85 to 265VAC
50/60Hz
20
3-wire RTD
input
Figure 3
24VDC Pulse Output option: Use the
same terminals and polarity as 4-20mA outputs (shown in Figure 3).
Warning: An independent redundant alarm should be used if control/alarm relay failure
could result in potential harm or damage.
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4. METER DESCRIPTION
1. Process Variable (PV) LED Display *
2. Setpoint Variable (SV) LED Display *
3. SCROLL key
4. UP and DOWN arrow keys
5. RETURN key
o
o
6. C / F Temperature unit indicators
7. Alarm, Control, Manual, Auto Tune status
indicators
* This display is also used for editing in the
programming mode
5. FRONT PANEL DESCRIPTION
5.1 PV (Process Variable) Display LEDs
Normal Operation
The top LED (red digits) displays the actual process measurement (temperature, voltage,
or current input signal). This is the "Process Variable" or PV.
Programming Mode
The red LEDs show the parameters for Programming Levels 1 through 4 (input type,
control action, etc.), one at a time. These parameters can be edited to suit the user's
requirements. Error messages are also displayed on these red LED Digits. Programming
details and error messages are explained later in this manual.
5.2 SV (Setpoint Variable) LED Digits
Normal Operation
During normal operation, the bottom LED (green) displays the user-programmable
Setpoint Variable (SV). This is the desired target to which the controller's output(s) will
adjust the process. To change the setpoint, use the up/down arrow keys. The setting
range equals the range the user selects in the LoLt (Low Limit) and HiLt (High Limit)
parameters during programming.
Programming Mode
The green LED display shows the actual data that can be edited for the parameter shown
on the red LED display. For example if the red LED is displaying Input Type, then the
green LED lists the input types in numerical order (for J, K, Analog, etc. types). The user
can then select the desired type. Refer to later sections for more on programming.
5.3 Status Indicators
'ALM 1' Status Indicator (Alarm Relay 1 Status LED)
This red LED is lit when the Alarm 1 relay is active. Also, this LED flashes when Alarm 1
is configured as an Event or Soak Timer and is in the process of counting down. Refer
to Appendix A and Section 11 for more on Alarm/Timer Functions.
'ALM 2' Status Indicator (Alarm Relay 2 Status LED)
This LED is lit in red when the Alarm 2 relay is active. Refer to Appendix A for more on
Alarm Functions.
'C1' Control Output 1 (Primary) Status Indicator
Illuminates in green when control output 1 is active.
'C2' Control Output 2 (Secondary) Status Indicator
Illuminates in green when control output 2 is active.
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'MA' Manual Mode Status LED
Illuminates when the controller is in Manual Mode of operation, which permits the user to
drive the control output manually. Refer to Section 10 for more details.
'AT' AUTO TUNE Status Indicator
When the controller is autotuning, this LED will blink. When the meter is finished tuning,
the LED will extinguish. Auto Tuning may take from several minutes to several hours
depending upon the process in question. Refer to Section 9.2 for more on Auto Tune.
'C' or ‘F’ Temperature Units Indicator for degrees C/F
LED Error Messages:
Err 1: A/D converter is inoperable. Unit must be repaired or replaced.
uuuu: Input under-range condition or input sensor not connected.
nnnn: Input over-range condition or input sensor not connected.
OPEN : Input sensor not connected or is inoperable.
5.4 Keypad Descriptions
SCROLL Key
While programming the controller you can move from one programmable parameter
to the next by pressing the Scroll key. The Scroll key is also used in combination with
the RETURN key to move between programming levels. The red LED display will
show each parameter title as you scroll through the list. Also, to activate an
autotuning session, press and hold this key for 5 seconds.
UP Arrow Key
Increases the Setpoint (SV) and increments parameter data when programming.
DOWN Arrow Key
Decreases the Setpoint (SV) and decrements parameter data when programming.
RETURN KEY
During normal operation, pressing the RETURN key permits the user to view the
controller's output action as a percentage (0.0 to 100.0% power). The lower (green)
display will indicate 'H' (heating outputs) followed by a percentage. After a few
seconds, the controller will automatically display a 'C' (cooling output). Press the
RETURN key from any mode to return to the normal SV display. The Return key
pressed with the SCROLL key moves from one programming level to the next.
Table I - Programming Level Parameters at a glance
1st Prog. Level
rAmp
oPoF
A1SP or timE
A2SP
2nd Prog. Level
Pb
CPb
ti
td
db
3rd Prog. Level
rEmo
P-L
A1Fu
A2Fu
A1HY
A2HY
Act
unit
dp
Ct
C Ct
HYST
EroP
Addr
PVoF
tYPe
LoLt
HiLt
Notes: Symbols shown above
are similar to the actual meter
LED displays which show
parameters in mixed case. Some
th
parameters and even the 4
programming level can be locked
out depending upon the setting in
rd
P-L (Parameter Lock in 3
programming level).
5
4th Prog. Level
LoCA
HiCA
tunE
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Ver. 2.0 11/99
6. FIRST PROGRAMMING LEVEL PARAMETERS
Press the SCROLL key to enter this level. Then use the SCROLL key to move through
the parameter list. To return to normal operation at any time, press RETURN key once.
Note: The configuration of the controller dictates which parameters appear. For
example, the 'ramp' parameter will not appear if ‘Parameter Lock’ (P-L) is set to '2'. Also,
A1SP will not appear if ‘A1Fu’ (Alarm 1 Function) is set to 8,9,10, or 11.
rAmp: Programmable rate of rise limit for PV. Permits the user to restrict the rate at
which the measured variable (PV) changes. Setting range: 0.0 to 100.0 units
per minute. Default = 0. The controller will monitor the changing PV and
override the controller output if necessary to limit the PV's rate of change.
oPoF: Output Offset. "Manual reset" function. The user can program a value (0.0 to
100.0%) which will then be added to the controller output percentage. For
example, if the oPoF parameter is set to 10.0%, the controller's output
percentage will always be 10% higher.
A1SP: Alarm 1 Setpoint value. First, set the desired Alarm type in the ‘A1Fu’ parameter
(refer to Appendix A for Alarm functions). Then program the desired limit here.
Allowable setting range is limited by parameter 'LoLt' and 'HiLt' (Low and High
Limit) settings.
timE: Programmable duration for the Event or Soak Alarm 1 Timer. The range is 0 to
9999 minutes. Refer to Section 11 and Appendix A for details on Soak/Event
Timers functions.
A2SP: Alarm 2 Setpoint value. First, set the desired Alarm type in the ‘A2Fu’ parameter
(refer to Appendix A for Alarm functions). Then program the desired limit here.
Allowable setting range is limited by parameter 'LoLt' and 'HiLt' (Low and High
Limit) settings.
7. SECOND PROGRAMMING LEVEL PARAMETERS
Press and hold the SCROLL and RETURN keys simultaneously to enter this level from
the previous programming level. To return to normal operation press the RETURN key.
NOTE: This is the Manual Tuning programming level. Rather than attempting a manual
tuning (manually setting values for the parameters in this level), it is strongly recommended
that AUTO TUNING be used to automatically set these parameters. If PID Tuning is
unfamiliar to you, manual tuning can cause severe process disturbances. Try Auto Tuning
first and then use Manual tuning afterward to fine tune the parameters if desired. For the
instructions on how to initiate an Auto Tune session, refer to Sec. 9.2.
Pb: Primary Output Proportional band value. Setting range from 0.0 to 100.0% of
controller's Span. Default = 10.0. Set Pb to 0.0% for ON/OFF control action.
This value is automatically calculated by activating the AUTOTUNE function
CPb: Secondary Output Proportional band value. Setting range from 0.0 to 100.0% of
controller's Span. Default = 10.0. Set CPb to 0.0% for ON/OFF control action.
ti: Integral (Reset) value. 0 to 3000 seconds setting range. Default = 240. This value is
automatically calculated by activating the AUTOTUNE function.
td: Derivative (Rate) Time. 0 to 3000 seconds setting range. Default = 40. This value is
automatically calculated by activating the AUTOTUNE function
db: Deadband: Setting range: -10.0% to +10.0% of Pb. Permits the user to set up a
"neutral" zone within the proportional band (around the main control setpoint)
where outputs 1 (Pri.) and 2 (Sec.) will not change state at the same time. Refer
to Appendix C for in-depth details on db.
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8. THIRD PROGRAMMING LEVEL PARAMETERS
Press and hold the SCROLL and RETURN keys simultaneously for 5 seconds to enter
this level from the previous programming level. To return to normal operation at any
time, press the RETURN key.
rEmo: Remote/Local toggle parameter. Set to "0" for local mode or "1" for optional
RS-485 PC communications remote mode. In remote mode, the controller's
keypad is inactive and only a connected PC can change the controller's
parameters. In local mode the controller's keypad is active.
P-L: Parameter Lock. This security feature locks out selected programming levels
prohibiting tampering and inadvertent programming changes. Depending upon
its setting, only certain parameters will display, refer to the list below.
Allowable setting range: 0 to 15;
0 - All parameters displayed are adjustable (level 1 parameters: A1SP, A2SP)
1 - Same as ‘0’(level 1 parameters displayed: Ramp, A1SP, A2SP)
2 - Same as ‘0’(level 1 parameters displayed: oPoF, A1SP, A2SP)
3 - Same as ‘0’(level 1 parameters displayed: Ramp, oPoF, A1SP, A2SP)
4 - same as '0', w/level 4 locked
5 - same as '1', w/level 4 locked
6 - same as '2', w/level 4 locked
7 - same as '3', w/level 4 locked
8 - same as '0', w/levels 3, 4 locked
9 - same as '1', w/levels 3, 4 locked
10 - same as '2', but levels 3, 4 locked
11 - same as '3', but levels 3, 4 locked
12 - same as '0', but levels 2, 3, 4 locked
13 - same as '1', but levels 2, 3, 4 locked
14 - same as '2', but levels 2, 3, 4 locked
15 - same as '3', but levels 2, 3, 4 locked
A1Fu: Alarm 1 Function. Select an Alarm / Timer function from the function list in
Appendix A.
A2Fu: Alarm 2 Function. Select an Alarm function from the alarm functions list in
Appendix A.
A1HY: Hysteresis for Alarm 1. The Setting range is 0.0 to 25.5% of the controller's span
settings. The controller's Span extends from the value programmed in 'LoLt' to
the value programmed in the 'HiLt' parameter (Low and High Limits). Hysteresis
is used to eliminate relay "chatter" by creating a deadband that extends from the
alarm setpoint down or up (depending upon the alarm type) where no relay
action can occur. The larger the hysteresis value the less the possibility of relay
chatter.
A2HY: Same as A1HY except for Alarm 2.
Act: Primary Output (Output 1) control action. Set to "0" for cooling (direct) action or "1"
for heating (reverse) action. Secondary Output (Output 2) is automatically
configured as a cooling output.
unit: Unit of measure selection. Program as follows:
Set to '0' for degrees F
Set to '1' for degrees C
Set to '2' for analog inputs
dP: Decimal Point selection.
Set to '00' for no decimal point
Set to '01' for 0.1 resolution
Set to '02' for 0.01 resolution (cannot use this setting for temperature inputs)
Set to '03' for 0.001 resolution (cannot use this setting for temperature inputs)
Ct: Primary Control Output 1 Cycle Time. Range: 0 to 100 seconds. This is the rate at
which the controller makes automatic output adjustments. The longer the time,
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the less responsive the controller will be to process changes. Set Ct for the
slowest rate possible without causing process oscillations; this will help to
prolong the life of the relay. Not used with analog outputs or ON/OFF control.
Set Ct to '1' second for the 24VDC Pulsed Voltage output option and '0' seconds
for the 4-20mA analog output option. Parameter 'Ct' is not used when ON/OFF
control is activated.
C Ct: Secondary Output 2 Cycle Time (same as Ct above except it is for the Secondary
Control Output)
Hyst: Primary Control Output 1 Hysteresis (used with ON/OFF control). Users can
create a deadband region from 0.0 to 25.5% of SPAN. Note: The SPAN is the
range that extends from the user-programmable Low Limit (LoLt) value to the
High limit (HiLt) value. Hysteresis is used to eliminate control relay chatter by
creating a deadband that extends from the setpoint down or up (depending upon
the relay's function) where no relay action can occur.
EroP: Error Protection. The desired state to which the Control and Alarm relay outputs
default in the event of controller error. Select a setting from Table II below.
Set
0
1
2
3
4
5
6
7
OUT 2
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Table II - Error Code Settings for Parameter ‘EroP’
ALM 2 ALM 1 OUT 1 Set OUT 2 ALM 2 ALM 1 OUT 1
OFF
OFF
OFF
8
ON
OFF
OFF
OFF
OFF
OFF
ON
9
ON
OFF
OFF
ON
OFF
ON
OFF
10 ON
OFF
ON
OFF
OFF
ON
ON
11 ON
OFF
ON
ON
ON
OFF
OFF
12 ON
ON
OFF
OFF
ON
OFF
ON
13 ON
ON
OFF
ON
ON
ON
OFF
14 ON
ON
ON
OFF
ON
ON
ON
15 ON
ON
ON
ON
Addr: Controller address used with the RS-485 communications option so that a PC can
recognize a specific 96VTR controller from among a group of 96VTRs or other
connected interface devices. Setting range is "0" to "31". Default = 0.
PvoF: PV Offset. Permits the user to offset the PV indication from the actual PV. For
o
example, if the thermocouple used is producing readings 2 higher than the
o
actual temperature across the range, the user can eliminate the 2 difference by
programming a "-2" value at this parameter. Overall range of the setting is -180
to +180. The default value is '0'.
tyPE: Sensor input selection. Select from the list below:
Set to '00' for J type thermocouple Set to '06' for S type thermocouple
Set to '01' for K type thermocouple Set to '07' for N type thermocouple
Set to '02' for T type thermocouple Set to '08' for RTD Pt100 ohm (DIN)
Set to '03' for E type thermocouple Set to '09' for RTD Pt100 ohm (JIS)
Set to '04' for B type thermocouple Set to '10' for Linear mode (analog)
Set to '05' for R type thermocouple
NOTE: To change a controller configured for a Thermocouple input to an RTD or
linear input, hardware modification is required. Please contact Extech for details.
LoLt: Low limit (of Span or Range). Set the Low Limit lower than the lowest expected
SV and PV display. Note that the low limit setting is limited by the range of the
type of input used (refer to Section 2.2 for ranges).
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HiLt: High limit (of Span or Range). Set High Limit higher than the highest expected SV
and PV display. Note that the high limit setting is limited by the range of the type
of input used (refer to Section 2.2 for ranges).
9. PARAMETERS IN THE FOURTH PROGRAMMING LEVEL
Press and hold the SCROLL and RETURN keys simultaneously for 5 seconds to enter
this level from the previous programming level. To return to normal operation at any
time, press the RETURN key.
LoCA and HiCA: Low and High Input Calibration values used for engineering units
scaling. Refer to Section 9.1 below for details.
tunE: Auto-tuning ‘automatic initialization mode’ selection. Select the criteria by which
the controller initiates an automatic Auto Tune session. Set this parameter as
desired from the Table in Section 9.2. To activate Auto Tune manually, refer
to Section 9.2.
9.1. CALIBRATION
Important Note: Special equipment is required to perform calibrations. Do not initiate
the calibration process unless fully prepared to do so.
a. "LoCA" (Low Calibration) is the first parameter to appear in this level.
b. For temperature inputs, connect a Thermocouple (mV) or RTD (resistance)
simulator to the controller's input terminals. For a process DC input, use a 4-20mA
or 1-5VDC signal, depending on the input type of the controller.
c. Apply the low input signal to the controller which corresponds to the range you are
using, i.e., for 4-20 mA inputs, 4 mA would now be applied to the controller.
d. Use the UP/DOWN arrow keys to set the value which will display when a 4mA
signal is applied to the controller. For example, for a 4-20mA unit to display from –
50 to +150, set ‘LoCA” to –50.
e. Press and hold the RETURN key for at least 5 seconds and the parameter on the
display will change from "LoCA" to "HiCA" (High Calibration). The Low Calibration
value is now written into the controller's non-volatile memory.
f.
Apply the high input signal to the controller which corresponds to the range you are
using. For example, for a 4-20mA input controller, apply a 20mA signal.
g. Use the UP/DOWN arrow keys to set the value which will display when a 20mA
signal is applied to the controller. For example, for a 4-20mA unit to display from –
50 to +150, set ‘LoCA” to +150.
h. Press and hold the RETURN key for at least 5 seconds. The display will change
from "LoCA" to "SP". The High Calibration value is now written into the controller's
non-volatile memory.
i.
Input a signal midway between the Low and High Calibration signals previously
applied (12mA in the example for a 4-20mA input) and verify that the display shows
a value midway between the high display and the low display. For the example
above, for a -50 to +150 display range, a 12mA input will display +50. If not, try the
calibration procedure again.
j.
Press the RETURN key when complete to return to normal operation.
9.2 AUTO TUNING
9.2.1 Auto Tune Initialization Modes
The Controller has the capability to start an Auto Tune session automatically. If this is
desired, select the conditions whereby an Auto Tune session will automatically begin
from Table III below. The controller defaults to Setting = ‘0’ (user initiates an Auto Tune
session). To manually initiate an Auto Tune session follow the procedure in Section
9.2.2.
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Setting
0
1
2
3
4
5
Table III - Programmable Auto Tune Initialization Modes
Auto Tune Initialization Modes
Autotune can only be initiated manually with the Setpoint (SV) not equal to the
Process (PV)
Autotune can only be initiated manually with the Process (PV) equal to the
Setpoint (SV)
Autotunes automatically when the controller is FIRST powered up if the PV < SV
Autotunes automatically when the controller is FIRST powered up if the PV = SV
EVERY time the controller is powered up the autotune process begins
automatically if the PV < SV
EVERY time the controller is powered up the autotune process begins
automatically if the PV = SV
9.2.2 Auto Tune Procedure
Note: For Auto Tune to be effective, the controller must be connected in line with
the working application. The process must be running as close to expected
operation as possible.
a.
b.
c.
d.
e.
In order to automatically set the Tuning parameters of Level 2 which are ‘Pb’
Proportional Band, ‘ti’ Integral time (also known as Reset), and ‘td’ Derivative time
(also known as Rate), first adjust the controller's setpoint (SV) to a value which
closely approximates your application.
Make sure that the value for Proportional Band (Pb) is NOT zero (zero initializes
ON/OFF control).
To initiate Auto Tune, press and hold the SCROLL key for at least 5 seconds until
the 'AT" status LED lights.
When Auto Tune is complete, the 'AT' status LED will extinguish. The new Tuning
values will now be stored in nonvolatile memory. Adjustments can be made
manually if desired in programming level 2.
To abort an Auto Tune process, simply press and hold the RETURN key for 5
seconds until the 'AT' LED extinguishes. Be careful not to hold it longer than it
takes for the 'AT' LED to extinguish otherwise you will access the MANUAL output
control mode inadvertently.
AUTO TUNE NOTE: The Auto Tune process can last from several minutes up to
several hours depending upon each individual process. However, if the Auto Tune
process does take an inordinate amount of time in a fast responding process, it is
recommended that the Auto Tune session be aborted by powering the controller down.
Check all physical connections as well as the controller programming to ensure that the
controller is properly configured in the system before trying another Auto Tune session.
10. AUTOMATIC AND MANUAL OUTPUT CONTROL
AUTOMATIC CONTROL
Automatic Control is the normal mode of controller operation and does not require
keystrokes or special menus to access. In automatic control mode the controller
automatically adjusts the percentage of both the Heating (Primary) and the Cooling
(Secondary) outputs so that the PV = SV.
MANUAL CONTROL
Manual control allows the user to manually drive the Primary and Secondary output
percentages from 0.0 through 100.0% (for testing purposes). To use this feature you
first have to unlock it. Press and hold the DOWN and RETURN keys until the display
flashes. Press and hold the RETURN key for 5 seconds to access the Manual Mode.
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The controller's output percent will now appear on the SV display preceded by an 'H"
for Heating or a 'C' for Cooling (depending upon how the action of the controller is
configured under the parameter 'act'). The 'MA' Manual status LED will also illuminate
and flash. To manually adjust the controller's output, use the UP and DOWN arrow
keys. For controllers using two control outputs (primary and secondary), the SV display
will automatically toggle between outputs 1 and 2. To return to normal operation, press
and hold the RETURN key until the 'MA' LED extinguishes. To Lock this feature, press
and hold the UP and RETURN keys until the display flashes. While locked, the Manual
Mode is inaccessible.
11. RAMP-TO-SETPOINT AND EVENT/SOAK TIMER FUNCTIONS
The Extech 96VTR controller operates as a fixed setpoint controller. However, the
controller offers several advanced features which can enhance your application. These
include Ramp-to-Setpoint and Event/Soak Alarm/Timers.
11.1 Ramp-to-Setpoint ('rAmP' Parameter)
To limit the rate at which the controller allows the process (PV) to move towards
setpoint (SV), enter a limit value in degrees (or other units) per minute in the 'rAmP'
parameter. The programmable limit ranges from 0.0 to 100.0 units per minute. The
controller will automatically adjust the controller's outputs to maintain the desired limit
programmed by the user. A setting of zero defeats the Ramp-to-Setpoint function.
11.2 Soak Timer Function (for use with Alarm 1 only)
The Alarm 1 Soak Timer allows the process to ramp to a setpoint and remain (Soak) at
that setpoint for a user-programmable period of time. Set the "A1Fu" parameter to
either '10' (Soak ON-TIMER) or '11' (Soak OFF-TIMER) depending upon the
application (See
Meter Contacts
Figure 4
Appendix A, Table
Control 16
IV, for the
Relay
difference between
18
ON- and OFFLoad
TIMERS). Set the
Alarm
12
Soak time in
Relay
13
parameter 'timE' in
the First
19
Programming Level.
AC
The Output and
20
Alarm Relays must
be wired in series
Example of Wiring Alarm and Control Relays in Series
so that the Alarm
relay can switch the control relay at the appropriate times (refer to Fig. 4). For
o
example, when a setpoint of 500 F is reached, the Soak time (programmed by the user
under parameter 'timE") begins to countdown. After the desired Soak time has elapsed,
the Alarm relay switches thereby switching the Control relay.
11.3 Event Timer (Alarm 1 relay only)
Alarm relay 1 can be programmed to switch state at desired times in a process. This is
accomplished by first setting the alarm function in parameter "A1Fu" to either an
EVENT-ON or EVENT-OFF Timer (See Appendix A, Table IV, for the difference
between ON- and OFF-TIMERS). Next, pick a count-down time. The relay timer will
start counting down once the PV equals the SV. The duration of the count-down is set
by the user at parameter "timE".
Application example: While maintaining a certain temperature for 4 hours, an event is
to take place 2 hours into the process. The event, in this example, is the controller's
alarm relay activating a pump. To do this, set the alarm function to an EVENT-ON
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Timer (selection 8) in parameter "A1Fu". Set the time to 120 minutes (2 hours) in
parameter "timE". When the controller is powered the alarm relay will be OFF, when
the PV = SV the relay remains OFF but the timer begins to countdown, and after 2
hours the relay will turn ON permitting the process event to take place.
12. RS-485 OPTION
The optional RS-485 PC interface permits up to 32 controllers to be connected to a PC for
remote operation. Each controller must have a unique address between 0 and 31 which is
programmed in parameter "addr". The "remo" parameter must be set to '1' to activate a
controller’s interface. The RS-485 wiring terminals are shown in Figure 3, Section 4.
Detailed information is provided with the purchase of the RS-485 option.
13. CUSTOMER SERVICE
Extech offers complete repair and calibration services for all of the products we sell.
For periodic calibration, NIST certification or repair of any Extech product, call customer
service for details on services available. Extech recommends that calibration be performed
on an annual basis to insure calibration integrity.
14. WARRANTY
EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects
in parts and workmanship for one year from date of shipment (a limited warranty may
apply on sensors and cables). If it should become necessary to return the instrument for
service during or beyond the warranty period, contact the Customer Service Department
at (781) 890-7440 for authorization. A Return Authorization (RA) number must be
issued before any product is returned to Extech. The sender is responsible for
shipping charges, freight, insurance and proper packaging to prevent damage in transit.
This warranty does not apply to defects resulting from action of the user such as misuse,
improper wiring, operation outside of specification, improper maintenance or repair, or
unauthorized modification. Extech specifically disclaims any implied warranties or
merchantability or fitness for a specific purpose and will not be liable for any direct,
indirect, incidental or consequential damages. Extech's total liability is limited to repair or
replacement of the product. The warranty set forth above is inclusive and no other
warranty, whether written or oral, is expressed or implied.
Copyright © 1999 Extech Instruments Corporation. All rights reserved
including the right of reproduction in whole or in part in any form.
APPENDICES
Appendix A: Alarm Mode Selections for parameters 'A1Fu' and 'A2Fu"
'00' Deviation High Alarm: For the Deviation High Alarm, the value entered for the
"A1SP" (Alarm 1 setpoint) or 'A2SP" (Alarm 2 setpoint) parameters equals the
amount the controller's HIGH alarm setpoint is offset from the main controller
setpoint. For example, if SV = 400 and A1SP = +10 then the Limit Alarm relay will
o
trip when the temperature reaches 410 . The Deviation alarm setpoint tracks the
main setpoint meaning that it changes as the main setpoint changes always
remaining a programmed number of units from the main setpoint.
'01' Deviation Low Alarm: With the Alarm setup as a Deviation Low Alarm, the value
entered for the "A1SP" (Alarm 1 setpoint) or 'A2SP" (Alarm 2 setpoint) parameters
equals the amount to which the controller's LOW alarm setpoint is offset from the
main controller setpoint. For example, if you entered SV = 400 and A1SP = -10
o
then the Alarm relay will trip when the temperature falls below 390 . The Deviation
alarm setpoint tracks the main setpoint meaning that it changes as the main
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setpoint changes always remaining a programmed number of units from the main
setpoint.
'02' Process High Alarm: Relay trips when the process (PV) exceeds the value
programmed at "A1SP" or "A2SP". Process alarms are fixed, absolute values and
do not change as the main control setpoint changes.
'03' Process Low Alarm: Relay trips when the process (PV) falls below the value
programmed at "A1SP" or "A2SP". Process alarms are fixed, absolute values and
do not change as the main control setpoint changes.
'04' Deviation High Alarm with Standby Sequence: Same as the Deviation High
Alarm but no relay action takes place until the process PV reaches the setpoint for
a second time. Standby sequence is also known as "Startup Inhibit" and is useful
for avoiding alarm trips during startup.
'05' Deviation Low Alarm with Standby Sequence: Same as the Deviation Low
Alarm but no relay action takes place until the process PV reaches the setpoint for
a second time. Standby sequence is also known as "Startup Inhibit" and is useful
for avoiding alarm trips during startup.
'06' Process High Alarm with Standby Sequence: Same as the Process High Alarm
but no relay action takes place until the process PV reaches the setpoint for a
second time. Standby sequence is also known as "Startup Inhibit" and is useful
for avoiding alarm trips during startup.
'07' Process Low Alarm with Standby Sequence: Same as the Process Low Alarm
but no relay action takes place until the process PV reaches the setpoint for a
second time. Standby sequence is also known as "Startup Inhibit" and is useful
for avoiding alarm trips during startup.
The following Alarm Timer Selections are available for Alarm 1 only
'08' EVENT ON-Timer: Upon power-up the alarm is de-energized. When the PV = SV
the alarm relay remains de-energized. When the timer counts down to zero, then
the relay energizes. Set the timer at parameter 'time' in Programming Level 1.
See Table IV below.
'09' EVENT OFF-Timer: Upon power-up the alarm relay energizes. When the PV =
SV the alarm relay remains energized. When the timer counts down to zero, then
the relay de-energizes. Set the timer at parameter 'time' in Programming Level 1.
See Table IV below.
'10' SOAK ON-Timer: Upon power-up the alarm relay is de-energized. When the PV =
SV the alarm relay energizes. When the timer counts down to zero the relay deenergizes. Set the timer at parameter 'time' in Programming Level 1. See Table IV
below.
'11' SOAK OFF-Timer: Upon power-up the alarm relay energizes. When the PV = SV
the alarm relay de-energizes. When the timer counts down to zero the relay
energizes. Set the timer at parameter 'time' in Programming Level 1. See Table IV
below .
A1Fu
Setting
8
9
10
11
Table IV - EVENT and SOAK Timer Relay States
Controller
When PV=SV
After Timer
ALARM RELAY MODE at Power-up
Timer Starts Counts Down
EVENT ON-TIMER
OFF
OFF
ON
EVENT OFF-TIMER
ON
ON
OFF
SOAK ON-TIMER
OFF
ON
OFF
SOAK OFF-TIMER
ON
OFF
ON
ON = Alarm Relay energized
OFF = Alarm Relay de-energized
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Appendix B: Application Programming Example
(Refer Fig.5). The aim is to maintain an
o
Alarm Annunciator
Figure 5
oven temperature of 500 F. The
controller monitors the oven temperature
Alarm Output
via the thermocouple. The controller
K Therm ocouple input
compares the actual temperature (PV) to
(Measures oven temp.)
o
the desired temperature (500 setpoint
96V TR
SV) and throttles the heater as needed
Compares oven
o
Oven
to maintain 500 F. If the oven
temperature with
desired setpoint
temperature reaches too high, the
and adjusts heater
controller's alarm output can trigger an
audio or visual alert. The alarm contact
Heater
Control Output
can also be used to switch on/off an
(Adjusts Heater)
external device such as a master switch
o
or cooling fan. In this example, the alarm will trigger an annunciator at 600 F. To program
the controller to perform the task described above, refer to the steps below. The
parameters not listed below are either inconsequential with regard to this example or they
will not appear on the controller display due to the controller configuration. Use the
programming level sequence shown below (i.e., Level 3 then Level 1. etc.)
Programming Level 3
A1Fu (Alarm Function): Set to '2' which is an absolute alarm meaning that the alarm is
o
o
fixed. In this case the alarm will be fixed at 600 F. This 600 F value is
programmed later in the procedure.
A1HY (Alarm Hysteresis): Set to '0'. Hysteresis is similar to 'deadband'. A region
extending from the alarm setpoint up or down, depending upon the alarm type,
where no relay action can occur to eliminate relay chatter.
Act (Action): This is control output action. Set to '1' for heating.
o
unit: Set to '1' for F
dp (decimal point): Set to '0' for no decimal point
Ct (Cycle time): To start off with, set to approx. 6 seconds. This can be re-adjusted later
after the process is observed. Cycle time is the rate at which the controller will
make adjustments to the heater. Set for the longest time possible (to save relay
life) without causing process oscillations.
tYPe: Set to '1' for a K Type Thermocouple
o
o
LoLt and HiLt (Low Limit / High Limit): Set these to 0 and 1000 respectively. This is
simply a span setting.
Programming Level 1
o
A1SP (Alarm Setpoint): Set to 600 F. Temperature at which the alarm relay will switch on the
alert annunciator.
Tuning the Controller (Level 2 parameters)
The best plan of attack with tuning is running the Auto Tune utility. Auto Tune will
automatically program the controller to respond with little process oscillation around
setpoint and minimal overshoot on oven heat-up. Run the Auto Tune utility per section 9.2
in this manual. Running Auto Tune supersedes programming Level 2 parameters.
Calibration (Level 4 parameters)
Calibration is very rarely required. If calibration must be performed refer to Section 9.1 for
details or contact Extech.
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Appendix C: Proportional Band and Deadband Details
The two diagrams shown below illustrate how the Proportional Band (Pb), Cooling
Proportional Band (CPb), and deadband (db) interact when controlling a process.
The region identified by the letter "A" reflects the action of the Proportional Band (PB). The
proportional band is the region in which the controller's primary output is permitted to throttle
between 0% and 100%. Outside this region the controller's primary output is either 0%
(above the band) or 100% (below the band).
The region indicated by the letter "B" reflects the action of the Cooling Proportional Band
(CPb) which is the region in which the controller's secondary (cooling) output is permitted to
throttle between 0% and 100%. Outside this region the controller's secondary output is either
0% (above the band) or 100% (below the band).
Figure Figure
6a - Positive
"db"
6
A
C
B
100
OUTPUT % Heat
Cool
0
PV
SP
Figure 6b - Negative "db"
B
A
100
O U TP U T %
Heat
Cool
PV
0
SP
C
FIGURE 6
The region indicated by the letter "C" reflects the action of the deadband (db) which
permits the user to decide whether or not the primary and the secondary outputs should
ever be ON at the same time. By setting the "db" to a positive value (Fig. 6a) the two
control outputs will never be ON at the same time (notice the deadband region in Fig. 6a).
Fig. 6b illustrates a negative deadband value which permits the primary and secondary
outputs' proportional bands to overlap causing the two outputs to potentially be ON at the
same time.
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