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USB Serial Converter ULI-321DK

USB to RS-232 connection! Industrial converter compatible with fixed serial numbers.

ULI-321DK is an industrial USB-to-serial converter that adds an RS-232 port to a PC's USB port. It supports USB 2.0 full speed (12Mbps) and enables high-speed data transfer of up to 921.6kbps for RS-232 communication. The locking serial number feature ensures that the COM port number remains fixed even when shared among multiple PCs, simplifying setup work in the field. Powered via the USB port, it requires no external power supply and features a compact inline design, making it ideal for control panels and field services. It can be easily set up on Windows 7/8/10/11 and Linux (Ubuntu). It comes with a USB cable for immediate use and is a highly reliable model perfect for connecting to test equipment and industrial devices.

Product page

basic information

- Interface: RS-232 (DB9 male) - Data rate: Up to 921.6kbps - USB specification: USB 2.0 full speed (12Mbps), Type B high retention connector - Power supply method: Powered by USB port (5VDC), power consumption <0.5W - Isolation protection: None (For isolation requirements, use ULI-321DC model) - Driver support: Windows 7/8/10/11, Linux (Ubuntu) - Operating temperature: 0–70°C, humidity 95% (non-condensing) - Enclosure/Mounting: IP30 plastic enclosure, inline installation - Size/Weight: 76.2×42.7×20.1mm, approximately 180g - Accessories: USB cable (0.9m) - Certifications: CE, FCC, RoHS

Price information

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Delivery Time

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The delivery time varies depending on the quantity, so please feel free to contact us.

Model number/Brand name

ULI-321DK

Applications/Examples of results

- Connection of industrial PCs and RS-232 devices (PLC, measuring instruments) - Data collection from Modbus RTU compatible devices via USB connection - Serial communication with a notebook PC for field service - USB to RS-232 conversion for testing equipment and lab instruments - Space-saving serial connection within control panels

Line up(1)

Model number overview
ULI-321DK(BB-232USB9M-LS) USB Type B ⇔ RS-232 (DB9), supports 921.6kbps, with locking serial number model.

Data Sheet: ULI-321D-Series

DOCUMENT

[Case Studies Included] Serial/USB Communication Devices Product Guide

PRODUCT

Recommended Products for Industrial Sites: Advantech Industrial IoT Systems & Devices Star Product Guide (2025)

CATALOG

Recommended products

Distributors

In 1983, Advantech (Advantech Co., Ltd.) was founded in Taiwan. For over 40 years, we have been developing high-quality and high-performance computers for industrial applications. As of 2024, we offer a lineup of over 3,000 various IoT devices. As the world's No. 1 manufacturer in the industrial computer market, with a presence in 95 cities across 26 countries, we aim to cultivate a prosperous future by solving social issues through AI × IoT platform services. *Source: OMDIA - No. 1 in global market share for industrial PCs, 42.5% (2023 edition)* In Japan, we established Advantech Co., Ltd. in 1997. In 2018, we formed a capital and business alliance with Omron Nogata Co., Ltd. to further expand sales and to quickly respond to market demands by offering design to production (DMS/ODM) services. By merging Taiwan's speed with the technological expertise we have cultivated over the years, we will establish a brand that meets the needs of our partners.