Omega Products CN3251-DT User Manual

1

⁄4 DIN Ramp/Soak Temperature/

Process Controller with Fuzzy Logic

CN3251

U Dual PID + Fuzzy

Logic Control

U Up to 5 Outputs–

Control, Alarm or Event

U Universal Sensor Input
U Switching Power

Supply 100 to 240 Vac
or Optional 12 to
24 Vac/Vdc

U 16-Segment

Ramp/Soak Program

U Optional RS232,

RS422, RS485 Digital
Communications

U Programmable Remote

Setpoint Input (Standard)

CN3251 1⁄4 DIN

Panel punches

available, visit

omega.com/

panelpunches

The CN3251 1⁄4 DIN temperature
and process controller is a cost
effective, high-performance, single
loop controller that can be used
for temperature, flow, pressure
and level control applications. With
universal sensor inputs and front
panel operator setup, one CN3251
controller can be easily field configured
for a wide variety of applications, and
simply reconfigured as application
needs change. This makes it an
exceptional choice for applications
requiring multiple control needs,
manufacturing facilities, testing
facilities and testing applications.

Features
5 Possible Outputs for single output or

heat/cool control, plus up to 3 alarms or
event outputs

Universal Sensor Input accepts
thermocouple, RTD or analog signals;
24 Vdc output for loop power

Self-Tuning with Fuzzy Logic
optimizes PID control and
minimizes overshoot

Digital Input for remote switching of
1 of the following:

U PID1/PID2
U Remote/local setpoint
U Main/auxiliary setpoint
U Ramp/soak operation
U Manual/auto control
U Alarm reset for latching alarms

16-Interval Ramp/Soak Program
with guaranteed soak, event outputs
and looping

U Optional programmable analog
U Programmable remote setpoint input

(standard on all products)

AUX Pushbutton and LED for front
panel switching of:

U PID1/PID2
U Remote/local setpoint
U Main/auxiliary setpoint
U Ramp/soak operation
U Manual/suto control

P-71

Security Code Protection prevents

unauthorized access
Setpoint Ramp Rate provides soft start

at power-up, or on setpoint changes, to
prevent uneven heating and overshoot

Control Loop Protection
provides process protection from:

U Open sensor
U Shorted sensor
U Sensor reversed
U Control output open or shorted
U Power control device open or shorted
U Load power missing and

self-diagnostics

Operating Ambient up to 65°C (150°F)

OMEGACARESM extended

SM

warranty program is available for
models shown on this page. Ask
your sales representative for full

Extended Warranty

Program

details when placing an order.
OMEGACARE
labor and equivalent loaners.

SM

covers parts,

Specifications

Control Modes:
Automatic: On/off, proportional, PID,

PI, PD, PID + fuzzy logic, heat/cool
(dual PID)

Control Adjustments:
Control Setpoint: Sensor range
Setpoint Limits: Sensor range
Deadband: 1 to 100°F
Proportional Band: Sensor range
Manual Reset: –99.9 to 99.9
Automatic Reset: 0.00 to 99.99

repeats per minute

Rate: 0 to 500 seconds
Output Cycle Time: 0.1 to

60.0 seconds

Output Limit: 0.0 to 100.0%
Open Sensor/Out of Range Output
Command: 0.0 to 100.0%
Display Offset: –100 to 100°F
Heat/Cool Adjustments:
Output Offsets: 0 to 100% of

proportional band

Cooling Medium: Air, water or oil
Alarm Adjustments:
Setpoints: High and low settings for

each alarm output
Alarm Types:
Absolute: High, low and high/low,
Tracking: +deviation, –deviation,
and ±deviation
Relay Action: Latching or non­latching, energized or de-energized
Alarm Deadband: Adjustable,

-18 to 38°C (0 to 100°F)
Alarm Inhibit: On power-up, enabled
or disabled
Control/Alarm Outputs: Total of
5 control/alarm outputs possible
Relay: Form A contacts, 1.0 A at
120/230 Vac (resistive load)
Solid State Relay Drive: 24 Vdc
nominal at 40 mA
Triac: 1 A continuous, 10 A in-rush
@ 120 or 230 Vac
Current/Voltage: 4 to 20 mA into 0 to
800 Ω, field-changeable to 1 to 5 Vdc

Output #5 (Optional):
Relay: N.O. form “C” contact,

5 A @ 120 or 2.5 A 230 Vac
Sensor Input: Field-selectable
thermocouple, RTD, current or voltage

Input Update Rate: 2 samples/s
Ramp/Soak Programming:
Intervals: 16
Loops: 1 loop, 0 to 255 times

or continuous

Event Outputs: Up to 3
Guaranteed Soak Differential: Off,

1°F to sensor span
Time Units: Seconds, minutes, hours
(1 s to 99.99 hours/segment)
Ramp to Setpoint: 1 to 9999°/hour
on power-up

Open Sensor and Out-of-Range
Condition: Programmable control

action with display indicating condition
“OPEN SENS”

Front Panel

Yellow LED’s

indicate control

output #1 or #2 on.

Yellow LED’s

indicate alarm or

event output on.

- Process variable display in operation mode.

- Alphanumeric menu display in setup mode.

(4 Red, 7-Segment LED’s)

RESET

Pushbutton

- Alarm reset.

- Hold for more than
3 seconds to enter
or exit setup mode.

- Scrolls through
menu in setup
mode.

AUX

Programmable

Pushbutton

- PID1/PID2 toggle switch.

- Auxiliary setpoint enable.

- Remote setpoint enable.

- Output disable.

- Ramp/soak operations.

- Auto/manual selector.

Remote Setpoint Input:
Input Signal: 4 to 20 mA, 250 Ω input

impedance, 1 to 5 Vdc, 110 KΩ input
impedance, voltage or current field­selectable via switch
Range: Programmable over-selected
sensor span
Accuracy: ±0.3% of sensor span (initial
accuracy) at 24°C (75°F) ambient
temperature and rated line voltage, field
calibrate to ±0.2% of sensor span

Digital Input: Accepts dry-contact closure
Analog Output Option:
Assignable Functions: Process

variable, output #1 command, active
setpoint, output #2 command
Output Signal: 4 to 20 mA into
0 to 800 Ω load, 1 to 5 Vdc into 100 KΩ
or greater load selectable via DIP switch
Range: Programmable over selected
sensor span for retransmission of
process variable and active setpoint,
fixed to 0 to 100% for transmission of
output commands
Accuracy: ±0.2% of programmed span,
±1 LSD

Digital Communications (Optional):
RS232: Single-drop, isolated
RS422/485: Multi-drop, isolated, field

selectable by switch

Lower Display

(4 Green 7-Segment LED’s)

- Active setpoint display in
operation mode.

- Menu value display in
setup mode.

Upper Display

Baud Rates: 1200, 2400, 4800,

9600, 19.2 K
Protocols: ASCII line, computer
interface
Instrument Power: 100 to 240 Vac,
10%, -15%; 12 to 24 Vac/Vdc, ±10%;
50 to 60 Hz
Operating Environment: 0 to 65°C
(32 to 150°F) ambient temperature,
relative humidity <95%, non-condensing

Dimensions:
Overall: 97 H x 97 W x 97 mm D

(3.8 x 3.8 x 3.8")

Depth Behind Panel: 97 mm (3.8")
Front Panel Projection: 20 mm (0.8")
Panel Cutout: 91 x 91 mm (3.6 x 3.6")
Weight: 454 g (1 lb)
Case Material: High-impact, black

ABS plastic

Influence of Line Voltage Variation:

±0.1% of sensor span/10% change in
nominal line voltage

Noise Rejection:
Common Mode Noise:

140 dB at 60 Hz
Series Mode Noise: ±0.1% of sensor
span with 300 mV peak-to-peak,
50 or 60 Hz series mode noise
RFI: Typically less than 0.5% of sensor
span at a distance of 1 m (3.1')
from transmitter (4 W, 464 MHz)

Front Panel

Setup of all control

parameters

and selections.

Green LED’s

indicate °C or

°F selected
for process

variable.

Yellow LED

indicates

an auxiliary

function

is active.

- In operation mode, pushbuttons
adjust setpoint.

- In setup mode, pushbuttons
increase/decrease menu values.

- While holding reset pushbutton,
increase/decrease page.

P

P-72