Photos show the actual item you will receive.
Product details
About this part
The EasySYNC ES-U-2101-MB USB Serial Adapter RS232 RS422 RS485 Isolated is made by EasySYNC and identified by manufacturer part number ES-U-2101-MB.
This listing is for the exact part number stated above. Compare the part number, condition and photos with your equipment before ordering.
Condition
This item is listed as New – Open Box. Unused. Packaging opened or missing.
The photos are part of the description — check them for labels, connectors, markings and any visible wear.
What's included
1 × EasySYNC ES-U-2101-MB USB Serial Adapter RS232 RS422 RS485 Isolated.
Only the items listed here or clearly shown in the photos are included. Cables, manuals, mounting hardware and accessories are not included unless stated.
Identification & compatibility
Check the manufacturer (EasySYNC), the part number (ES-U-2101-MB) and the photos against your equipment. If you are not sure this is the right part, contact us before you order.
Price match
Found an identical item for less at a fixed price elsewhere? Contact us before you buy with the details, and we will review it.
Important information
Product information is based on what is available for this specific item. Where specifications or compatibility are critical to your application, confirm them before purchase.
- Brand
- EasySYNC
- Part number
- ES-U-2101-MB
- Model
- ES-U-2101-MB
- Country of Origin
- Taiwan
- Type
- USB to RS-232 / RS-422 / RS-485 converter, 1 port
- Isolation
- 2000 V DC optical isolation per port
- Surge protection
- ESD and power surges up to 25 kV
- Mode selection
- 4 DIP switches (outside); termination and bias by internal jumpers
- Serial connectors
- DB-9 male and 6-way screw terminal block
- USB connector
- USB Type-B (photo)
- Power
- USB powered
- Auxiliary output
- Optional 5 V, up to 150 mA, terminal pin 5 (jumper)
- RS-232 signals (DB-9)
- TxD, RxD, RTS, CTS, GND
- Indicators
- PWR, RxD, TxD LEDs
- Case
- Metal, with mounting flanges
- Drivers (manual)
- Virtual COM port: Windows 7 to 11, macOS 10.9+, Linux kernel 3.0.0-19+
The EasySYNC ES-U-2101-MB is a single-port, optically isolated USB to RS-232 / RS-422 / RS-485 converter in a metal case, powered from the USB port. It adds one serial COM port to a PC through a virtual COM port driver, and the serial mode is chosen with four DIP switches on the outside of the unit. The part number is also written ES U 2101 MB. The EasySYNC line is documented by Connective Peripherals.
What does the -MB version have?
Per the Connective Peripherals manual, the ES-U-2101-MB has one port that supports RS-232, RS-422 and RS-485, a metal case, USB power, optical isolation, a 6-way screw terminal and jumpers inside for termination and biasing. Each port is isolated with 2000 V DC optical isolation and protected by a surge protector against ESD and power surges up to 25 kV.
How is the serial mode selected?
With the DIP switches S1 to S4: RS-232 is OFF-ON-ON-ON, RS-422 4-wire is ON-ON-ON-ON, RS-485 full duplex is ON-OFF-ON-ON, RS-485 half duplex with echo is ON-OFF-OFF-ON and without echo ON-OFF-OFF-OFF. Set the switches before connecting to the serial bus. Inside the case, jumpers enable 120 ohm termination and 750 ohm bias resistors.
Which RS-232 signals are available?
In RS-232 mode the ES-U-2101-MB uses a reduced signal set. On the DB-9 male: RxD (pin 2), TxD (pin 3), GND (pin 5), RTS (pin 7) and CTS (pin 8); the other pins stay unconnected. On the terminal block only RxD, TxD and GND are used, plus an optional 5 V output on pin 5 (up to 150 mA, enabled by an internal jumper, off by default).
What is in the photos?
The unit with its mounting flanges, the USB-B port, the 6-way green terminal block, PWR / RxD / TxD LEDs, the red 4-way DIP switch and the DB-9 male serial connector. A printed "master" sticker is on the top, and the bottom has tape residue. Condition: new, open box.
- Ships from
- Israel
- Tracking
- Included on every order
Import duties and taxes may apply in your country and are paid by the buyer on delivery.
- Returns
- Not accepted
Return terms differ from item to item — this item's own policy is shown above.
Whatever it says, an item that arrives faulty or not as described is covered: tell us within 30 days of delivery and we will refund or replace it.
Consumers in the EU, the UK and Israel keep their legal right to cancel within 14 days. Full details and the return request form are on our Returns and warranty page.
Questions about this part
What is the EasySYNC ES-U-2101-MB?
A single-port USB to serial converter that can run as RS-232, RS-422 or RS-485, with 2000 V DC optical isolation and a metal case.
What is a USB to RS485 converter?
A device that lets a PC talk to RS-485 equipment, such as PLCs, drives or meters, over USB. The PC sees it as a COM port through a virtual COM port driver.
What is the difference between RS232, RS422 and RS485?
RS-232 is a single-ended point-to-point link. RS-422 uses differential pairs for longer lines with one transmitter. RS-485 is differential and supports several devices on one bus, in 2-wire half duplex or 4-wire full duplex. The ES-U-2101-MB supports all three, selected by DIP switch.
Is the ES-U-2101-MB isolated?
Yes. The manual lists 2000 V DC optical isolation on each port of the ES-U-21xx series, plus surge protection up to 25 kV ESD.
Does it need an external power supply?
No. Connective Peripherals lists it as USB powered. It can also give 5 V at up to 150 mA on terminal pin 5 if the internal jumper is set.
What condition is it in?
New, open box. A printed "master" sticker is on the top and there is tape residue on the bottom.
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