Honeywell UDC3500 Digital Controller

Fits 1/4 DIN panel temperature and process control where you need a universal digital controller with multiple analog/digital inputs, 0.10% accuracy, NEMA 4X / IP66 front face, and optional Ethernet or RS485 Modbus.

Key advantages

1/4 DIN universal control — multi-input temperature/process controller for panel OEM and retrofit work.
0.10% accuracy class — published for the UDC3500 family under specification 51-52-03-40.
NEMA 4X / IP66 front — washdown-capable panel face with dual-display family UI.
Optional Ethernet / Modbus — 10Base-T TCP/IP and/or RS485 Modbus by order option.

Typical applications

1/4 DIN panel loops needing a universal digital controller with math and alarms.
Retrofits replacing legacy UDC panels where I/O map and outputs must match.
Machines that optionally add Ethernet or RS485 Modbus for supervisory links.

Selection guide

Form factor — 1/4 DIN universal digital controller; multiple analog/digital inputs (see 51-52-03-40).
Accuracy — 0.10%.
Outputs — Multiple output types (relay/SSR/current); math; alarms; setpoint programming per specification.
Supply — Per model selection guide (universal AC typical).
Front ingress — NEMA 4X / IP66.
Display — Multi-segment dual display family (UDC3500).
Communication — Optional Ethernet 10Base-T TCP/IP and/or RS485 Modbus (see 51-52-03-40 options).
Mounting — 1/4 DIN panel mount.
Notes — Specification 51-52-03-40 + Product Manual 51-52-25-120 Rev.4 (Mar 2012). Lockheed addendum 51-52-99-36 is stored under certificates/honeywell (not a general ops manual). Exact ambient and supply strings are order-guide fields — confirm in RFQ.

Common mistakes

Ordering without locking the I/O and output map (relay vs SSR vs current) from 51-52-03-40.
Assuming Ethernet or Modbus is standard — both are optional; confirm the communication option on the model code.
Ignoring panel cutout and NEMA 4X / IP66 gasket install details for washdown fronts.
Treating the Lockheed addendum as a general operations manual — it is not.
Expecting a single published supply voltage string from this page — supply is per model selection guide.
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When to RFQ / what to tell us

Input types (thermocouple / RTD / mA / V / digital) and number of loops.
Output types needed (relay / SSR / current), alarms, and whether setpoint programming/math is required.
Communication need (none / RS485 Modbus / Ethernet TCP/IP).
Available supply (per selection guide) and panel constraints (1/4 DIN, NEMA 4X/IP66 front).
Quantity and ship-to country.

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Specs

Spec	Value
SKU	27094
Brand	Honeywell
Model	UDC3500
Product type	other (universal digital controller)
Form factor	1/4 DIN; multiple analog/digital inputs (see 51-52-03-40)
Accuracy	0.10%
Output	Relay/SSR/current; math; alarms; setpoint programming per specification
Supply voltage	Per model selection guide (universal AC typical)
IP / NEMA	Front face NEMA 4X / IP66
Display	Multi-segment dual display family (UDC3500)
Communication	Optional Ethernet 10Base-T TCP/IP and/or RS485 Modbus
Mounting	1/4 DIN panel mount
Notes	Specs from Honeywell 51-52-03-40 + Product Manual 51-52-25-120 Rev.4 (Mar 2012).

Documents

Honeywell UDC3500 specification (PDF)

FAQ

Q: What accuracy does the UDC3500 publish? A: 0.10% per the OEM extract / specification 51-52-03-40.

Q: Is Ethernet or Modbus included? A: Optional Ethernet 10Base-T TCP/IP and/or RS485 Modbus — lock the option on the model code.

Q: What front rating applies? A: Front face NEMA 4X / IP66 when installed per the specification.

Q: What should I send for a quote? A: I/O map, outputs, communication, supply, quantity, ship-to. Compatible with systems using Honeywell UDC3500 if you need a drop-in check — we do not claim authorized-dealer status.