User Manual
FCC Compliance Statement 
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against 
harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause 
harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or 
television reception, which can be determined by turning the equipment o and on, the user is encouraged to try to correct the interference by one or more of the following measures:
•  Reorient or relocate the receiving antenna.
•  Increase the separation between the equipment and receiver.
•  Connect the equipment into an outlet on a circuit dierent from that to which the receiver is connected.
•  Consult the dealer or an experienced radio/TV technician for help 
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any 
interference received, including interference that may cause undesired operation. Changes or modications not expressly approved by StarTech.com could void the user’s authority to operate the 
equipment.
Industry Canada Statement 
This Class B digital apparatus complies with Canadian ICES-003. 
Cet appareil numérique de la classe [B] est conforme à la norme NMB-003 du Canada.
CAN ICES-3 (B)/NMB-3(B)
Use of Trademarks, Registered Trademarks, and other Protected Names and Symbols 
This manual may make reference to trademarks, registered trademarks, and other protected names and/or symbols of third-party companies not related in any way to 
StarTech.com. Where they occur these references are for illustrative purposes only and do not represent an endorsement of a product or service by StarTech.com, or an endorsement of the product(s) 
to which this manual applies by the third-party company in question. Regardless of any direct acknowledgement elsewhere in the body of this document, StarTech.com hereby acknowledges that all 
trademarks, registered trademarks, service marks, and other protected names and/or symbols contained in this manual and related documents are the property of their respective holders. Phillips is a 
registered trademark of the Phillips Screw Company in the United States and other countries. Linux® is the registered trademark of Linus Torvalds in the U.S. and other countries. Windows® is a registered 
trademark of Microsoft Corporation in the United States and/or other countries. macOS is a trademarks of Apple Inc., registered in the U.S. and other countries.
Technical Support 
StarTech.com’s lifetime technical support is an integral part of our commitment to provide industry-leading solutions. If you ever need help with your product, visit www.startech.com/support and 
access our comprehensive selection of online tools, documentation, and downloads. 
For the latest drivers/software, please visit www.startech.com/downloads
Warranty Information 
This product is backed by a two-year warranty. 
StarTech.com warrants its products against defects in materials and workmanship for the periods noted, following the initial date of purchase. During this period, the products may be returned for 
repair, or replacement with equivalent products at our discretion. The warranty covers parts and labor costs only. StarTech.com does not warrant its products from defects or damages arising from 
misuse, abuse, alteration, or normal wear and tear.
Limitation of Liability 
In no event shall the liability of StarTech.com Ltd. and StarTech.com USA LLP (or their ocers, directors, employees or agents) for any damages (whether direct or indirect, special, punitive, incidental, 
consequential, or otherwise), loss of prots, loss of business, or any pecuniary loss, arising out of or related to the use of the product exceed the actual price paid for the product. Some states do not 
allow the exclusion or limitation of incidental or consequential damages. If such laws apply, the limitations or exclusions contained in this statement may not apply to you.
Jumper group settings cont’d
Terminations Use the Terminations jumper group to 
dene which of your send and receive 
communication pins are on and o for 
each port.
Notes: 
•  Because RS-232 utilizes dierent 
communication pins and additional 
signals can cause interference, it’s 
recommended that all terminators 
be set to o in RS-232 mode. 
•  While standard terminations for 
each mode are recommended, your 
termination requirements may vary 
depending on your application 
and the specic device you’re 
communicating.
Both RX+/
RX- and TX+/TX- 
terminators are 
disabled
(Terminators for 
RS-232 mode) 
(default)
TX+/TX- 
terminators are 
enabled
(Standard 
terminators for
RS-485 2-wire 
mode)
RX+/RX- 
terminators are 
enabled
Both RX+/
RX- and TX+/TX 
terminators are 
enabled
(Standard 
terminators for
RS-422 and 
RS-485 4-wire 
mode)
ON OFF
ON OFF
ON OFF
ON OFF
About the LED indicators
The adapter features two sets of LED indicators for each port:
•  The Port mode LEDs illuminate solid to indicate what mode each 
port is set to. 
•  The Port send/receive LEDs blink to indicate that data is being sent 
or received.
485-2
485-4
422
232
RI
+5V
AUX
RX+
RX-
TX+
TX-
Mode group
Power group
Terminators group
Jumper group settings
There are dierent settings that you can dene for each port: Mode, 
Power and Termination. Each setting has its own jumper group used 
to dene each port set. 
The tables below outline the available settings for each jumper 
group.
ON OFF
Mode (COM Standard) Use the Mode jumper group to dene 
the serial communication standard each 
port uses.
Note: If the mode is set to RS-232 it’s 
important to set all terminations to 
the o position (see Jumper group 
settings, Terminations for details).
RS-232
(default)
RS-422
RS-485
4-wire
RS-485 
2-wire
Power (Pin-9) Use the Power jumper group to dene 
the pin-9 power requirements for each 
port. 
Note: AUX outputs power consistent 
with the power adapter connected to 
the Power adapter port on the USB to 
serial adapter hub.
AUX  
power adapter 
on pin-9
+5V DC 
on Pin-9
No power 
on pin-9 
(default)


