Starting at $1,345.00
  • Usually ships in 16-20 weeks



  • 1/4 DIN
  • 3 universal analog inputs
  • 0.10% accuracy
  • 166ms scanning rate
  • Up to 3 analog outputs
  • Up to 5 digital outputs
  • Jumper free configuration
  • NEMA4X and IP66 front face protection
  • Multilanguage prompts
  • 4 digital inputs (optional)
  • Math functions (optional)
  • Ethernet or RS-485 communication (optional)
  • Infrared PC and Pocket Configuration (optional)
  • Heathwatch Maintenance Tool (Optional)
  • Cascade or 2 Loops of control (Optional)


The Honeywell UDC3500 universal digital controller packs new powerful features in the popular 1/4 DIN size.

Unmatched application power includes: infrared (IR) configuration interface, three universal analog inputs, two loops of control and two math algorithms. When these are combined with the Accutune III™ tuning with fuzzy logic overshoot suppression, the result is price/performance leadership.

Application flexibility is assured by the universal analog inputs, universal AC power supply, four digital inputs, a maximum of seven analog and digital outpus, infrared, RS422/485 Modbus RTU or Ethernet 10Base-T TCP/IP Modbus communication protocols, simple configuration plus total field upgrade capability for any optional feature.

Analog Inputs

The UDC3500 has up to three universal analog inputs with a typical accuracy of ±0.10% of full-scale input and a typical resolution of 16 bits. These can easily be configured to operate as 2 universal and 2 high level or as 1 universal and 4 high level inputs.

All analog inputs are sampled six times per second (every 166 milliseconds). The first, or process variable input, can be one of various thermocouple, RTD, radiamatic or linear actuations. Linear actuations have thermocouple, RTD and radiamatic transmitter characterization capability as a standard feature. Linear actuations also have square root capability.

The optional second and third inputs are isolated from each other and all other circuits and accept the same actuations as input one. These optional inputs can each be split into two high level inputs. The fourth input is enabled by first configuring input 2 as a 20 mA or 5 Vdc input type (HLAI). Input 5 is then available as a high level input.


Here's how some of our customers use this product...

Automated Quenching Applications

The Background: Our customer is an industrial metalworks that has an automated process for quenching hot metals. They seek a reliable controller to regulate this process.

The Problem: Quenching is the rapid cooling of metal by water, oil or air. It is done to achieve certain properties within that metal such as hardening. To obtain the desired result, quenching must be done at specific temperatures for a specific amount of time. If the metal piece is cooled too much, too little, too quickly or too slowly, the piece may be rendered unsuitable for its intended use.

The Solution: We recommended the Honeywell UDC3500 universal digital controller in a dual loop configuration. The first loop will control the temperature of the water, oil or gas being used to quench the metal while the second loop will determine the temperature differential between the metal and the water, oil or gas being used.