CN740-Series

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.