Serial converters for industrial use

Our USB to RS485 converters

We are specialized in making converters for usb, RS485, RS232 and RS422, targeting customers who needs converters that have better quality than the cheap un-isolated, but smaller and less expensive than the industrial types of converters.
All our converters are isolated, powered from the usb side, and with virtual comport drivers.

flag Dublin, IrelandJul. 2013
Very satisfied with the service and product supplied by Hjelmslund. Very fast response time, even when we required a special assembly. High quality product, worked excellently first time.

John Clarke - Nines Engineering
Website :

Isolated USB to RS485 converter - USB485-STISO

USB485-STISO  - 2 wire half duplex RS485 converter.

USB485-STISO : USB to RS485 converter with 2500 volt isolation

Connect your control network to the PC with an isolated RS485 converter, using it as a virtual com port.
Its isolation barrier and readiness for Modbus gives it the quality needed for use in industrial automation.
2 wire half duplex w. Automatic Rx/Tx switching and Rx/Tx FIFO for smooth operation - no programming of RTS to set the direction, and no dip-switches.

USB485-STIXL  - as STISO, but larger terminals.

PDF Icon  USB485-STISO/STIXL product sheet

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Isolated USB to RS485 / RS422 converter - USB485-STI4W

USB485-STI4W  - 4 wire full duplex RS485 / RS422 converter.

USB485-STI4W : Isolated USB RS485/422 converter

Our 4 wire full duplex model of USB to RS485 converters.
The receiver is always enabled, but the transmitter is only enabled during data transmission, thus making it possible to use it even as a slave device.
Drives up to 256 nodes, 1Mbps, 2.5kV isolation voltage.

PDF Icon  USB485-STI4W product sheet

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USBISO-AA : USB isolator and protection device
USBISO-AA  USB isolator and protection device.

USBISO-AA : USB isolator and protection device  USBISO-AA : USB isolator and protection device  USBISO-AA : USB isolator and protection device

USBISO-AA : Driverless USB isolator and protection for USB 2.0 full speed systems.

The USBISO-AA isolator is intended to be used in industrial environments to prevent groundloops, and where the host computer needs to be isolated and protected from external electrical interference.

Brief specs.
- 1.000 Volt DC isolation
- IEC 61000-4-2 Level 4 ESD Protection
- USB 2.0 Full Speed
- Can deliver 200mA to the external USB device
- No drivers needed, can function with all systems

PDF Icon  USBISO-AA product sheet

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USB RS485 converter with RJ45

USB485-MB45  RS485 with cable and RJ45 - for Modbus.

USB485-MB45 : Isolated RS485 converter with cable and RJ45 for Modbus

The RJ45 is wired according to the Modbus specifications Ver 1.02   Section 3.5.1

Pin 4 : Data - (B)
Pin 5 : Data+ (A)
Pin 8 : Common

Extremely flexible shielded cable where the shield is connected to Modbus 'common' internally in the converter.
Standard cable length is 3 meter, but 1.5 / 5 / 10 meter versions will be available as well.

PDF Icon  USB485-MB45 product sheet

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USB232-STISO : Isolated USB to RS232 converter

More compact than other isolated converters.

Our USB to RS232 converter provides 2.500Volt electrically isolation, supports up to 1Mbps speed and includes 256 bytes Tx FIFO and 128 bytes Rx FIFO for smoother data transmission. And last but not least, compact and space saving.

Isolated - USB powered - Virtual comport drivers.

- Order: USB232-STISO
- Price: € 55 @1

PDF Icon  USB232 product sheet

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USB232-STISO : Isolated USB to RS232 converter

USB232-STISO  Isolated RS232 converter.

USB232-STISO : Isolated USB to RS232 converter          USB232-STISO : Isolated USB to RS232 converter

Panel mount USB to RS485 converter

Panel mount USB to RS485 converter

USB485-GISO : Panel mount RS485 converter

Superior system separation with panel mounted electrically isolated USB to RS485 converter

Mount it as any other port in your enclosure, with the USB connection outside and the RS485 cable inside. By placing your isolation barrier in the cabinet side, you avoid getting USB cables into your industrial installation, as well as avoiding having industrial communication near your pc, hence maintaining the best possible system separation.

The perfect match for your PLC installations and industrial communication networks.

The USB to RS485 converter are available in both isolated and non-isolated models.

Our panel mount USB485

PDF Icon  USB485-GISO product sheet

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Contact info

Updated - 21 March 2014.