Photos show the actual item you will receive.
Product details
About this part
The Connective Peripherals ES-U-2101-MB Isolated USB Serial Adapter RS232/422/485 is made by Connective Peripherals 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 × Connective Peripherals ES-U-2101-MB Isolated USB Serial Adapter RS232/422/485.
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 (Connective Peripherals), 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
- Connective Peripherals
- 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, optically isolated
- Isolation
- 2000 V DC optical isolation per port
- Surge protection
- Up to 25 kV ESD
- Serial connectors
- DB-9 male and 6-way screw terminal block
- Mode selection
- 4 external DIP switches (RS-232, RS-422, RS-485 full/half duplex)
- RS-232 signals (DB-9)
- TxD, RxD, RTS, CTS, GND
- Power
- USB powered; optional 5 V, 150 mA output on terminal pin 5 (jumper)
- USB connector
- USB Type-B
- LEDs
- PWR, RxD, TxD
- Chipset / drivers
- FTDI; virtual COM port drivers for Windows 7 to 11, macOS 10.9+, Linux kernel 3.0.0-19+
- Enclosure
- Metal, wall-mountable flanges
- Markings
- CE, FCC, RoHS
- Country of origin (label)
- Taiwan
The Connective Peripherals ES-U-2101-MB is a single-port, optically isolated USB to serial adapter that adds one RS-232, RS-422 or RS-485 port to a PC through USB. It is USB powered, sits in a wall-mountable metal case, and has a DB-9 male connector plus a 6-way screw terminal block. The isolation and surge protection make it suited to factory automation equipment, multi-drop data collection, scales and other serial devices in industrial environments.
How do you select RS-232, RS-422 or RS-485?
Four DIP switches on the outside of the case set the mode (S1-S4): RS-232 = OFF ON ON ON; RS-422 4-wire with handshaking = ON ON ON ON; RS-485 full duplex (4-wire) = ON OFF ON ON; RS-485 half duplex (2-wire) with echo = ON OFF OFF ON, without echo = ON OFF OFF OFF. Termination and bias resistors are set with internal jumpers, and an internal jumper enables an optional 5 V, 150 mA output on terminal pin 5 (off by default).
What is the difference between RS-422 and RS-485 on this adapter?
RS-422 uses separate transmit and receive pairs (TX+/TX-, RX+/RX-) for a full-duplex point-to-point link. RS-485 can run full duplex on 4 wires or half duplex on one pair (Data+/Data-) for 2-wire multi-drop buses. The ES-U-2101-MB supports both, plus RS-232.
Which signals are on the DB-9 in RS-232 mode?
The ES-U-2101-MB has a reduced RS-232 set: pin 2 RxD, pin 3 TxD, pin 5 GND, pin 7 RTS, pin 8 CTS; pins 1, 4, 6 and 9 must be left unconnected. On the terminal block in RS-232 mode only RxD (2), TxD (3), optional 5 V (5) and GND (6) are used.
What is in the box?
The adapter in its original Connective Peripherals box with a card insert pointing to the online documentation and drivers. The box label reads P/N ES-U-2101-MB, Qty 1 PC, COO TW. 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 ES-U-2101-MB?
A Connective Peripherals single-port USB to serial adapter with RS-232, RS-422 and RS-485 modes and 2000 V DC optical isolation, in a metal case.
What is the difference between RS-422 and RS-485?
RS-422 is a full-duplex link with separate transmit and receive pairs. RS-485 can also run half duplex on a single pair and supports multi-drop buses. This adapter does both, selected by DIP switch.
Does it need an external power supply?
No. It is powered from the USB port.
Can it power a small device?
Yes, after setting an internal jumper it supplies 5 V at up to 150 mA on pin 5 of the terminal block. It is off by default.
Which operating systems are supported?
Connective Peripherals lists virtual COM port drivers for Windows 7 to Windows 11, macOS 10.9 onwards and Linux kernel 3.0.0-19 onwards; it uses an FTDI chipset.
Does it have full RS-232 handshaking?
No. In RS-232 mode the DB-9 carries TxD, RxD, RTS, CTS and GND only; DCD, DTR, DSR and RI are not available.
What condition is it in?
New, open box, in the original Connective Peripherals box.
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