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CN740-Series
1/16 DIN Temperature Controllers with Autotune, Alarms and RS485
Models In Stock
This item is discontinued. Please see the CND3-SERIES as a possible alternatives. Contact Engineering if you have any questions
- 1/16 DIN temperature controller with Dual Display
- Autotune
- RS-485 Communications
- Free Software
CN740-Series
From
$
187.65
Models In Stock
Product Overview
- Accuracy ± 0.25 %
- Accuracy Detail ± 0.25% span, ± 1 least significant digit
- Data Interface RS485 Modbus
- Depth Behind Panel 80 mm
- Display Size 6.35 mm (.25 in)
- Display Type 4 Digit LED
- Display Type Note 3.5 Digit Dual Display, Two 4-digit, 7 segment 6.35 mm H (0.25") LEDs PV: Red SV: Green
- Enclosure Ratings IP66
- Form factor 1/16 DIN
- Front Bezel 48 mm²
- Input Type Thermocouple, RTD, Thermistor
- Measurement Type Temperature
- Measuring Range Type B : 100 to 1800°C, Type S : 0 to 1700°C, Type R : 0 to 1700°C, Type N : -200 to 1300°C, Type E : 0 to 600°C, Type T : -20 to 400°C, -200 to 400°C, Type J : -20 to 400°C, -100 to 850°C, Type K : 200 to 1300°C, -200 to 500°C, Type L : -200 to 500°C, Type U : -200 to 800°C, RTD : 0 to 100°C, -20 to 500°C, -200 to 600°C
- Memory Backup Non-Volatile
- Number of Control Outputs 1
- Number of Inputs 1
- Operating Temperature, Max 50 °C
- Operating Temperature, Min 0 °C
- Panel Thickness, Max 9.5 mm
- Series ID CN740-Series
- Supply Power Note 100 to 240 Vac, 50/60 Hz
- Supply Power Type AC
- Supply Voltage 100 to 240 Vac
- Weight 114 g
Supported Applications
The Omega CN740 Series consists of microprocessor-based temperature process controllers designed for panel mounting in a compact 1/16 DIN package. These units provide accurate temperature measurement and control, supporting both direct (heating) and reverse acting (cooling) applications. The series is engineered to manage simple ON/OFF control or more complex PID functions with manual tuning or autotuning capabilities.
Operating Conditions & Performance
The CN740 Series operates within an ambient temperature range of 0 to 50°C (32 to 122°F). The controllers feature a dual LED display showing Process Value and Set Point simultaneously, with engineering units selectable in °F or °C. Accuracy is specified as ±0.25% span, ±1 least significant digit.
Input capabilities cover a broad spectrum of thermocouple types (B, S, R, N, E, T, J, K, L, U) and Pt100Ω RTD sensors across various temperature ranges:
- B: 100 to 1800°C (212 to 3272°F)
- S/R: 0 to 1700°C (32 to 3092°F)
- N/K: -200 to 1300°C (-328 to 2372°F)
- E: 0 to 600°C (32 to 1112°F)
- T/J: -20 to 400°C (-4 to 752°F)
- L/U: -200 to 800°C (-328 to 1472°F) and -200 to 500°C (-328 to 932°F)
- Pt100Ω RTD: Ranges include 0 to 100°C (32 to 212°F), -20 to 500°C (-4 to 932°F), and -200 to 600°C (-328 to 1112°F)
The unit carries CE and UL approvals. The enclosure rating is IP66.
Configuration Options
The series offers three primary output configurations, each including RS485 communications:
- CN743: Relay output with RS485 communications.
- CN742: DC pulse (Voltage Pulse) output with RS485 communications.
- CN745: 4 to 20 mA current output with RS485 communications.
All models include two alarm outputs supporting 12 preprogrammed alarm functions. Power supply requirements are AC 100-240V, 50/60 Hz. The physical dimensions for the CN740 front bezel are 48 mm² (1.89 in²), requiring a panel cutout of 45 mm² (1.77 in²). Maximum supported panel thickness is 9.50 mm (0.375") with a required panel depth of 80 mm (3.15").
Available accessories include the CNQUENCHARC noise suppression RC snubber for 110 to 230 Vac and the CN7-485-USB-1 RS485 to USB mini-node converter.
Key Product Differences
The primary distinction between models in this series is the control output type. The CN743 utilizes a mechanical relay, while the CN742 provides a DC pulse signal and the CN745 delivers an analog 4 to 20 mA current loop. All three variants share identical input sensor ranges, display resolution (6.35 mm H / 0.25" LEDs), autotune functionality, RS-485 communication protocols, and physical housing dimensions.
PDFs & Manuals
Software & Drivers
Show Ratings & Reviews
Rated 5 out of
5
by
Just some guy from
inexpensive, works well.
I use this controller to maintain the temp in a molten salt furnace. With the auto tune it holds a constant temp with minimal over shoot and fast reaction time.
Date published: 2016-03-03
Rated 2 out of
5
by
Mr Z from
Reliability is marginal
Originally had six units, three failed after 1 year. The internal relay contacts became intermittent, one fused in the "on" position. They are only switching 2 amps, and are rated for 5.
Date published: 2017-02-24
Rated 5 out of
5
by
DONG SHIK from
Great service
Arrived super fast. I ordered a wrong item and wanted to exchange it, and the return and exchange process was simple and fast.
Date published: 2026-06-13
Rated 5 out of
5
by
John Orzechowski from
CN9000A Replacement
Perfect replacement to the CN9000A, to be used in a NASCAR Oil Temperature Heater control for warming the engine oil and circulation before the engine is started. With this ability we don't have keep as close as an eye on the oil temperature in the tank while working this process that takes approximately 1 hour.
Date published: 2025-09-07
Rated 4 out of
5
by
MaryP from
1/16 DIN Temperature Controllers
Product works well and can easily be integrated with most controls systems. The only complaint is that the lead time is often quite long if the items are not in stock.
Date published: 2023-11-06
Rated 2 out of
5
by
MDIAS LLC from
Incorrect controller purchased
Cannot give a good rating becauae I was unable to use this product due to incorrect purchase. I found it difficult to select the correct type of controller on the site.
Date published: 2023-03-12
Rated 5 out of
5
by
oventec from
good price,
works perfec, twe can use for temperature, RH, presu
Date published: 2021-10-16
Rated 5 out of
5
by
John6800 from
Controller features have On/Off and PID Control
Because this controller has both On/Off & PID Control I was able to configure it to my oven.
Date published: 2018-03-28
For the CN745, I did not see an "Output" option in the Communication Parameters List. Does this exist?
Thank you for the inquiry. Please forward this question to TEMP@OMEGA.COM so that we can better support you.
Best regards
OMEGA
Date published: 2021-09-13
for CN745, the product does require any solid state relay? I am not sure that in case of current output control any solid state relay is required. Could you recommend any solid state relay or items which are required to be purchased with the CN745?
Output #1 is an analog control output that can be programmed using the PID tuning parameters.to control your process. You can either manually tune the PID values, or use Auto tune providing the process is for temperature and you have a set point at least 100 degrees (C or F) above your starting ambient temperature.
Date published: 2021-09-13
Can this model be used for over-temperature protection?
Hi Kathy,
The CN743 would not be recommended for use as a limit controller. The CN2516-R1 would be a 1/16 DIN size controller that would be suited for use as an over-temperature limit controller. It has the ability to latch which is what you'll want as a feature in a true limit controller.
Date published: 2021-09-13
Can you please share connection for CN743 with out SSR? I need to connect it with out using SSR. Please share the power supply connection for this.
Thank you for your inquiry. Due to this being a more complicated issue please call 1-888-826-6342, ask for Temperature Engineering or send an email to temp@omega.com
Date published: 2023-06-09
Does CN740 comes with mounting bracket?
Thank you for your inquiry. The mounting bracket is included.
Date published: 2023-11-22
I would like to speak with a technical rep regarding the operation of the CN74-3 temp controller. I am Working from Home (WFH). I do not have controller in front of me (located 34 miles from here).
Thank you for your inquiry. Feel free to call our Temperature Group at 1-888-826-6342 to discuss application. We are available until 6:30 EST
Date published: 2021-09-13
Does cn743 model comply with REACH and RoHS ?
Thank you for your inquiry. Unfortunately this product does not comply with RoHS and/or REACH.
Date published: 2022-07-07
Does CN743 require SSR? Can you please explain connection in video? By the Data file i can not understand the connections.
Thank you for the inquiry. The answer will depend on if your load pulls over the maximum current rating for the CN743's relay, which is 5 Amps. If your load pulls under 5 Amps, you will not require an SSR.
Date published: 2023-06-09