Wavelength Electronics LFI-3751 User manual

LFI-3751 with Autotune PID
Thermoelectric Temperature Controller
Key Features . . .
•< 0.002°C temperature stability even at ambient
•Controls temperature with thermistors, RTDs, LM335, or AD590
The LFI-3751 with Autotune PID is a high performance
temperature controller specifically designed for sensitive
applications. Now with Autotune PID capability, the
LFI-3751 automatically optimizes virtually any thermal
load; reduce overshoot or improve temperature stability
with the push of a button.
. . . The Wavelength Advantage
Autotune PID
PID Constants adjustable via front panel
Auto-ranging thermistor & RTD bias current
Bipolar or Unipolar output current operation
High and Low Temperature Limits
Auxiliary temperature sensor input
Analog input allows for external temperature control
(Analog model only)
Addressable RS-232 interface
LFI3751-00400-C Rev D

The Front Panel at a Glance
2
2
1
mV / K
SENSOR
avelength Electronics
5 Amp - 40 Watt
Temperature Controller
BA
POWER
LM335
AD590
Thermistor T , R
3, 3
2, 2
1, 1
RTD
11T , R
2
1
A / K
µ
T , R
HOLD FOR LOCAL
RS-232
C
T , R
mV offset
A offset
T , R
µ
3
2
3
2
W
AMPS
RS-232 ADDRESS
VOLTS
ON
PACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
ERROR
°C
k
HOLD SHIFT FOR
OUTPUT
SHIFT
MODEL LFI-3751
STATUS
TEMP LIMIT
REMOTE
T LIMIT LIMIT I
SENSOR
Off
On
Status Section
4 Digit Display
Display
Select
Switch
Sensor
Reference
Section
AC Power Switch
Digi-Pot
Adjust Knob
Display
Section
Units of
Measure
Shift Button
Output Section
}
Temp Limit
Button
Output Button

3
While displayed, Parameter
can be changed by rotating
Digi-Pot Adjust Knob
Digi-Pot Adjust Knob
is disabled. Monitor
parameter only.
LED is OFF
LED is lit SOLID
LED FLASHES
Front Panel Operations at a Glance
Operation Legend
Adjusting Limit Current
Rotate the Display Select Switch to LIM I.
Positive Limit Current (0 to +5 Amps) will
alternate with the Negative Limit Current
(-5 to 0 Amps).
LIMIT I LIMIT I LED flashes:
TE Current is limited by
LIM I settings.
WAIT - Most thermal loads require maximum
current while initially controlling to temperature.
To control properly, the output current must be
less than the LIM I current setting.
CAUTION: Improperly set LIM I
can damage your thermoelectric
Limit Current LED
ERROR
SENSOR
ON
OUTPUT
IS SENSOR
ERROR CONDITION
CORRECTED?
BEEP
ON
OUTPUT
3
BEEPS
LONG
BEEP
IS SENSOR
ERROR
CONDITION
CORRECTED?
NO
YES
YES
NO
PRESS
OUTPUT
BUTTON
SENSOR ERROR LED
flashes: Sensor is either
OPEN or SHORTED. Output
forced OFF.
Press Output Button to
re-enable output current.
Press Output Button
to clear error.
Sensor Error LED & Correcting the Sensor Error
T LIMIT
ON
OUTPUT
OVER / UNDER
TEMPERATURE
CONDITION
CORRECTED?
ON
OUTPUT
BEEP
3
BEEPS
LONG
BEEP
OVER / UNDER
TEMPERATURE
CONDITION
CORRECTED?
YES
NO
YES
NO
PRESS
OUTPUT
BUTTON
T LIMIT LED flashes:
Sensor temperature is
outside temperature
limits. Output is disabled.
Press Output Button to
re-enable output current.
Press Output Button to
clear error.
Temperature Limit LED & Correcting the Temperature Limit Error
Press &
Release
TEMP LIMIT
TEMP LIMIT 1
°C°C
TEMP LIMIT 2
(Cycles three times, then reverts to prior display)
T LIMIT
Adjusting Temperature Limits : -199.9 to +199.9°C
PACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
AMPS
PACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
AMPS
Negative LIM I
Positive LIM I
Note: Temperature Limit does not
operate in Resistance Mode for
thermistors or RTDs.

4
ONON PRESS &
RELEASE
PRESS &
RELEASE
ON
Output Current
Disabled
Output Current
Enabled
Output Curren
t
Disabled
Enable / Disable Output Current
Press & Hold
for more than
3 seconds
TEMP LIMIT
BUTTON
RS-232
REMOTE
RS-232
REMOTE
OPERATE VIA
RS-232
REVERT TO
LOCAL OPERATION
Revert to Local Mode Operation
RS-232
REMOTE
BEEP
REMOTE RS-232 LED flashes,
unit BEEPS:
RS-232 communication is
initiated and the port is active.
A flashing RS-232 LED indicates active communication
between computer and instrument
Remote RS-232 LED
A solid RS-232 LED indicates the instrument is under
remote RS-232 control, but communication between
computer and instrument is not active.
RS-232
REMOTE
SHIFT
BEEP BEEP
Continuously
Hold the Shift
Button
After 3 seconds, REMOTE RS-232
LED lights solid red, unit beeps.
RS-232 Address
Displayed while Shift
Button is held. When
Button released, new
address (if changed) is
saved and unit beeps.
Adjusting RS-232 Address
TEMP LIMIT
BUTTON
Remote RS-232
Operation
Output shuts off,
Unit remains in
RS-232 operation
Press and Hold
TEMP LIMIT and Press
OUTPUT BUTTON to
shut output off
OUTPUT
OUTPUT
RS-232
REMOTE
RS-232
REMOTE
ON
Enable / Disable Output Current During Continuous RS-232 Operation

5
The Front Panel at a Glance
Quick Autotune PID Operation
Quick Autotune PID Operation
Step 1. Adjust the Limit Current below the rated
maximum current for your thermoelectric or
resistive heater.
Step 2. Adjust the Temperature Setpoint to your desired
operating temperature.
PACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
AMPS
PACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
AMPS
Negative LIM I
Positive LIM I
(-5.00 to 0.00 Amps)
decrease
increase
(0.00 to 5.00 Amps)
Ω
PACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
°C
k
temperature (°C)
or resistance (kΩ)
displayed
-199.9˚C to +199.9˚C
or
0 to 500 kΩ
decrease
increase
Continued next page...

6
Step 3. Adjust the P term to display AutS or Autd.
AutS: Setpoint Response Optimization
Autd: Disturbance Rejection Optimization
(Wait about two seconds before enabling the
output current.)
Step 4. Begin Autotune Optimization: Enable Output
Current.
The time to complete an Autotune optimization
sequence varies from load to load. While tuning,
the ON LED will flash. When complete, the
LFI-3751 beeps once and the ON LED lights solid.
Three audible beeps indicate if the Autotune
sequence is aborted. The ON LED is not lit. If the
actual sensor temperature exceeds the high or low
temperature limits the optimization will abort.
See Page 23 for more detail on the LFI-3751
Autotune feature.
The Front Panel at a Glance
Quick Autotune PID Operation
Quick Autotune PID Operation, continued
PACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
decrease
increase
AutS or Autd (below 0)
ON PRESS &
RELEASE
ON
Output Current
Disabled
Autotune
Optimization
in Progress,
ON LED flashes
Autotune
Complete
BEEP
Phase 1: The LFI-3751 ramps the thermoelectric
current to drive the load toward the setpoint
temperature.
Phase 2: The LFI-3751 performs three characterization
passes.
Phase 3: The LFI-3751 reverts to normal operation,
saving the optimized P, I, and D settings in
non-volatile memory and settling in at the
setpoint temperature.
Ambient
Phase 1
First
Pass
Setpoint
Phase 2 Phase 3
Second
Pass
Third
Pass
Autotune Process

7
Thermistors or
RTDs (T, R) data
[C1]
[C2]
Thermistors or
RTDs (T, R) data AD590, LM335,
Slope
[B1] only
[B1]
[B2]
[A1]
[A2]
OFF (0)
OR
1 to 100 secs.
OFF (0)
OR
0.4 to 10.0 secs.
AutS or Autd
(Autotune PID)
or
1 to 100 Amps / Volt
°C
k Ω
°C
k Ω
°C
AD590, LM335,
Offset
[C1] only
k Ω
I
D
B
C
SHIFT
OFF
-8.00°C to +150.00°C
(typical)
AMPS
POSITIVE
NEGATIVE
AMPS
-12.0 to +12.0 Volts VOLTS
-199.9°C to +199.9°C
OR
0 to 500 k Ω
- 5.00 to +5.00 Amps AMPS
-199.9°C to +199.9°C
OR
0 to 500 k Ω
°C
k Ω
OR
OR
°C
k Ω
°C
PACT T
SET T
TE I
LIM I
AUX T
0.00 to +5.00 Amps
-5.00 to 0.00 Amps
TE V A
SHIFT
ON
Thermistor
RTD
AD590
LM335
10°C
1
2
3
25°C
0°C
1 µA / K
10 mV / K
19.9 kΩ
1
2
3
10 kΩ
0.100 kΩ
-
-
40°C
100°C
0 µA
0 mV
5.326 kΩ
0.139 kΩ
-
-
Default Sensor Configuration
The Front Panel at a Glance
Displaying and Adjusting Values on the Front Panel
Display Section
A B C
Sensor Type [A1] [A2] [B1] [B2] [C1] [C2]

Rear Panel at a Glance
115/230 VAC, 50/60 Hz, 160 VA
CAUTION
Do Not Open
Risk of Electrical Shock
Ne Pas Ouvrir
Risque d’ Electrocution
ATTENTION
VORSICHT
Hochspannung
Nicht ffnen
MADE IN USA
SELECT:
(5x20mm SLO BLO)
FUSE (250V):
2000 maT @ 115V
1000 maT @ 230V
Wavelength Electronics
Bozeman, Montana USA
OUTPUT
8F0-2995S/N
LINE:
ANALOG
INPUT
RS-232 OUTPUT
RS-232 INPUT
115V
Analog Input
BNC Connector
Output
Connector
(9 pin male
D-sub plug)
RS-232 Input
Connector
(25 pin female
D-sub receptacle)
RS-232 Output
Connector
(25 pin male
D-sub plug)
AC Voltage
Select Switch
Do not change this
setting while power is
supplied to the unit.
AC Fuse
For 115 VAC operation, install a 2000 maT 5 x 20 mm SLO BLO fuse
For 230 VAC operation, install a 1000 maT 5 x 20 mm SLO BLO fuse
AC Power
Entry Module
Use only the power cable
provided. Ensure that the
power source you plug
the LFI-3751 into is
properly grounded.
!
1
9
Serial
Number
Fan Vent Holes
Do Not Block or place
any objects within 6" of
the rear panel of
this instrument.
1
25 25
1
13 13
14 14
Earth Ground
If your AC power system
does not bring earth
ground through the
AC Power Entry Module,
connect earth ground
via a 16 AWG wire to
this screw terminal.
5
6
8
1
2
3
4
5
6
7
8
9
TEC +
TEC -
Aux Sensor +
*Sensor -
Main Sensor +
AD590 Voltage
*Fan -
*Fan+ (+12 V)
*-12 V
2
3
7
5, 6, 8, & 20 shorted
All other pins are floating
Instrument Receive (In)
Instrument Transmit (Out)
Signal Ground
2
3
7
All other pins are floating
Peripheral Transmit (Out)
Peripheral Receive (In)
Signal Ground
Output
9 pin male D-sub plug
RS-232 Input
25 pin female D-sub receptacle
RS-232 Output
25 pin male D-sub plug
*Thermally Fused to 100 mA

9
In This Book
Quick Start. Chapter 1 prepares the temperature controller for
use and familiarizes you with a few of its features.
Front Panel Operation. Chapter 2 details the features and
functions of the front panel. You will find this chapter useful
whether you are operating from the front panel or from the
RS-232 interface.
Rear Panel Operation. Chapter 3 details the rear panel
features and connector pin outs.
Remote Interface Reference. Chapter 4 details the RS-232
commands and responses. Remote interface programs are
provided to help you develop programs for your temperature
control application.
Specifications. Chapter 5 lists the temperature controller
specifications.
If your LFI-3751 fails within one year of purchase, Wavelength
Electronics will repair it free of charge. If you have questions
relating to the operation of the LFI-3751, you can contact
Technical Support:
Call [phone] in the U.S.
Fax [phone]
email [e-mail]
If you have purchased the controller from an international
distributor, please contact them for technical support or
repairs.

10
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