SeaLevel SEALINK+485I User manual

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© Sealevel Systems, Inc. 2104 Manual | SL9092 9/2021
SEALINK+485I
User Manual | 2104

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© Sealevel Systems, Inc. 2104 Manual | SL9092 9/2021
Contents
CONTENTS...........................................................................................................................................................2
INTRODUCTION ...................................................................................................................................................3
BEFORE YOU GET STARTED ...............................................................................................................................4
INSTALLATION .................................................................................................................................................... 5
HARDWARE INSTALLATION ............................................................................................................................... 6
CONFIGURATION .................................................................................................................................................8
TECHNICAL DESCRIPTION ...............................................................................................................................10
SPECIFICATIONS ...............................................................................................................................................11
APPENDIX A –TROUBLESHOOTING................................................................................................................12
APPENDIX B –HOW TO GET ASSISTANCE .....................................................................................................13
APPENDIX C –ELECTRICAL INTERFACE ........................................................................................................14
APPENDIX D –GROUND LOOP PHENOMENON..............................................................................................15
APPENDIX E –ASYNCHRONOUS COMMUNICATIONS ..................................................................................16
APPENDIX F –SILK-SCREEN ............................................................................................................................17
APPENDIX G –COMPLIANCE NOTICES ..........................................................................................................18
WARRANTY ........................................................................................................................................................19

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© Sealevel Systems, Inc. 2104 Manual | SL9092 9/2021
Introduction
Overview
The Sealevel Systems SeaLINK+485I equips the PC with 1 isolated USB to RS-422/485 Asynchronous serial
port providing a versatile interface for common RS-422/485 needs. The SeaLINK+485I connects through
the PC’s external USB port, so it does not require opening the computer case. Resources such as IRQ’s and
I/O addresses are also not utilized. It does require a system that supports USB in hardware and operating
system.

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Before You Get Started
What’s Included
The SeaLINK+485I is shipped with the following items. If any of these items is missing or damaged,
contact the supplier.
•SeaLINK+485I Isolated USB to RS-422/485 Serial I/O Adapter
•USB Cable Part Number CA179 for Connecting to Upstream Host/Hub
Advisory Conventions
Warning
The highest level of importance used to stress a condition where damage could result to the
product, or the user could suffer serious injury.
Important
The middle level of importance used to highlight information that might not seem obvious or a
situation that could cause the product to fail.
Note
The lowest level of importance used to provide background information, additional tips, or other
non-critical facts that will not affect the use of the product.

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Installation
Operating System Installation
For Windows Users
Begin by locating, selecting, and installing the correct software from the Sealevel software driver database.
SeaCOM software can also be downloaded from the 2104-product webpage: SeaLINK+485I Product
Other Operating Systems
Refer to the appropriate section of the Serial Utilities Software.
For additional software support, please call Sealevel Systems’ Technical Support, [phone]. Our
technical support is free and available from 8:00AM-5PM Eastern Time, Monday through Friday. For email
support contact: mailto:supp[email protected].
You are now ready to proceed with connecting the 2104 to your system. Refer to the Hardware
Installation section for details.
Windows NT is not USB aware and thus cannot support this
device.

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Hardware Installation
The screen captures below are taken from a Windows 7 installation. Your particular operating system may
differ slightly from what is shown based on your version of windows.
The SeaLINK+485I can be connected to any Upstream Type “A” port either at the PC host or an Upstream
Hub. The SeaLINK+485I is hot-pluggable, meaning there is no need to power down your computer prior to
installation. The SeaLINK+485I has an onboard 8 position dip switch that is used to configure the interface.
Prior to connecting the SeaLINK+485I, be sure to configure this dip switch for your specific application.
Please see the Configuration section for more information. The SeaLINK+485I is defaulted to RS-422 mode
so changes are only required if you will be using the product in an RS-485 application.
1. After installing the software connect SeaLINK+485I to an Upstream Host or Hub.
This indicates that the system has recognized the new device and will now proceed to locate and
automatically install the driver.
This window indicates that the device has been successfully installed. You may see these windows appear
as a balloon in the bottom right corner of your desktop momentarily instead of as a window. If you view
your system’s Device Manager at this point, you should have a new “COM” port in the Ports (COM & LPT)
Device Class. It should look similar to the screen shot on the following page.

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HARDWARE INSTALLATION, CONTINUED
You can access your new COM: port by using the assigned COM: identifier shown above. In this case, it is
COM5: but this assignment will vary from system to system. At this point, the hardware is recognized. To
verify operation, use Sealevel Systems supplied WinSSD diagnostic utility. WinSSD can be found in the
Start Menu under the SeaCOM group.

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Configuration
Electrical Interface Selection
The port on the SeaLINK+485I has the ability to be used in both half and full duplex RS-422/485 applications.
This is selectable through DIP-switch SW1. The chart below describes each of the switch position’s function.
Please refer to the following page for switch setting examples. Switch SW1, in the “ON” position, either
enables, adds, or connects, based on the function of the switch position listed below. Switch SW1, position
OFF, disables, removes, or disconnects .
SW1
Function
1
RS-485 Two Wire Auto Enable/Disable
2
Echo Enable/Disable
3
Adds or removes the 120-ohm termination
4
Adds or removes the 1K ohm pull-up resistor in the RS-422/RS-485 receiver circuit
(Receive data only)
5
Adds or removes the 1K ohm pull-down resistor in the RS-422/RS-485 receiver
circuit (Receive data only)
6
Connects the TX+ to RX+ for RS-485 two wire operation
7
Connects the TX- to RX- for RS-485 two wire operation
8
Not Used

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CONFIGURATION, CONTINUED
Switch Examples
Please use the following examples to configure your adapter.
Figure 2 is the first RS-485 picture: 1 ON, 2 off, 3 ON, 4 ON, 5 ON, 6 ON, 7 ON, 8 off.
Figure 3 is the second RS-485 picture: 1 ON, 2 ON, 3 ON, 4 ON, 5 ON, 6 ON, 7 ON, 8 off.
ON
1 2 3 4 5 6 7 8
OFF
RS-422
Figure 1 - RS-422, 4 Wire RS-485 (Default)
OFF
ON
RS-485 1 2 3 4 5 6 7 8
OFF
Figure 2 - RS-485, 2 Wire with Echo
ON
RS-485 1 2 3 4 5 6 7 8
OFF
Figure 3 - TD-485, 2 Wire No Echo

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© Sealevel Systems, Inc. 2104 Manual | SL9092 9/2021
Technical Description
The SeaLINK+485I: utilizes a USB UART. This chip features programmable baud rate, data format, 128-
byte Dual Port RX Buffer, and 256-byte Dual Port TX Buffer. The RS-422/485 transceiver supports data
rates from 300 baud up to 921.6K baud.
Features
•Hot-Pluggable device
•Does not require opening the case
•No system resources are required (i.e., I/O ports or IRQ’s)
•LED status indicators for “USB Enabled”, “TD”, and “RD”
Connector Pin Assignments (DB25 Male)
The SeaLINK+485I complies with the EIA-530 pin out with the following signals supported
Signal
Name
Pin #
Mode
GND
Ground
7
RDB
RX+
Receive Positive
16
Input
RDA
RX-
Receive Negative
3
Input
TDB
TX+
Transmit Positive
14
Output
TDA
TX-
Transmit Negative
2
Output
The modem control signals are internally biased as follows: RTS is connected to CTS, DTR is
connected to DCD and DSR, and RI is tied inactive.

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Specifications
Environmental Specifications
Specification
Operating
Storage
Temperature Range
0º to 50º C (32º to 122º F)
-20º to 70º C (-4º to 158º F)
Humidity Range
10 to 90% R.H. Non-Condensing
10 to 90% R.H. Non-Condensing
Manufacturing
All Sealevel Systems Printed Circuit boards are built to UL 94V0 rating and are 100% electrically tested.
These printed circuit boards are solder mask over bare copper or solder mask over tin nickel.
Power Consumption
Supply line
+5 VDC
Rating
100 mA
Mean Time Between Failures (MTBF)
Greater than 150,000 hours. (Calculated)
Physical Dimensions
Package Length
3.8 inches (9.66 cm)
Package Width
2.3 inches (5.84 cm)
Package Height
1.0 inches (2.54 cm)

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© Sealevel Systems, Inc. 2104 Manual | SL9092 9/2021
Appendix A –Troubleshooting
Serial Utility test software is supplied with the Sealevel Systems adapter and will be used in the
troubleshooting procedures. Using this software and following these simple steps, most common
problems can be eliminated without the need to call Technical Support.
1. If your adapter isn’t working, first check to make sure that USB support is enabled in
the System BIOS and it is functioning properly in the operating system. This can be
done by using either the Windows 98/ME or Windows 2000 Device Manager.
2. Ensure that the Sealevel Systems software has been installed on the machine so that
the necessary files are in place to complete the installation.
3. When the SeaLINK+485I is configured properly, the USB Enabled LED (EN) will be lit.
This should allow you to use Sealevel’s WinSSD utility and the supplied loopback plug
to check communications. The supplied loopback plug connects TD to RD. If you
decide to test the Modem Control Signals, a full pin loopback plug will be required.
Details on loopback plugs are included within WinSSD. Contact Sealevel Systems if
you need further assistance.
4. When testing the SeaLINK+485Iin loopback mode, you should see both the TD and RD
LED’s flashing as well as seeing echoed data on the screen. The loopback test first
transmits a HEX pattern, 55AA, and then an ASCII string of data. If this test passes,
then the SeaLINK+485Iis ready for use in your application.
5. Please note that if the card is configured for 2 wire RS-485 with no echo a loopback
test is not possible. The receiver in this case will be turned off and the test will fail. If
you plan on using this device in two wire mode test the adapter in RS-422 mode first.
Then configure the adapter for your application.

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Appendix B –How To Get Assistance
Please refer to Troubleshooting Guide prior to calling Technical Support.
Begin by reading through the Trouble Shooting Guide in Appendix A. If assistance is still
needed, please see below.
When calling for technical assistance, please have your user manual and current adapter
settings. If possible, please have the adapter installed in a computer ready to run diagnostics.
Sealevel Systems provides an FAQ section on its web site. Please refer to this to answer many
common questions. This section can be found at http://www.sealevel.com/faq.asp.
Sealevel Systems maintains a web page on the Internet. Our home page address
is www.sealevel.com. The latest software updates, and newest manuals are available via our
web site.
Technical support is available Monday to Friday from 8:00 a.m. to 5:00 p.m. eastern time.
Technical support can be reached at [phone].
RETURN AUTHORIZATION MUST BE OBTAINED FROM SEALEVEL SYSTEMS BEFORE RETURNED
MERCHANDISE WILL BE ACCEPTED. AUTHORIZATION CAN BE OBTAINED BY CALLING SEALEVEL
SYSTEMS AND REQUESTING A RETURN MERCHANDISE AUTHORIZATION (RMA) NUMBER.

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Appendix C –Electrical Interface
RS-422
The RS-422 specification defines the electrical characteristics of balanced voltage digital interface circuits.
RS-422 is a differential interface that defines voltage levels and driver/receiver electrical specifications. On
a differential interface, logic levels are defined by the difference in voltage between a pair of outputs or
inputs. In contrast, a single ended interface, for example RS-232, defines the logic levels as the difference
in voltage between a single signal and a common ground connection. Differential interfaces are typically
more immune to noise or voltage spikes that may occur on the communication lines. Differential interfaces
also have greater drive capabilities that allow for longer cable lengths. RS-422 is rated up to 10 Megabits
per second and can have cabling 4000 feet long. RS-422 also defines driver and receiver electrical
characteristics that will allow 1 driver and up to 32 receivers on the line at once. RS-422 signal levels range
from 0 to +5 volts. RS-422 does not define a physical connector.
RS-485
RS-485 is backwardly compatible with RS-422; however, it is optimized for party line or multi-drop
applications. The output of the RS-422/485 driver is capable of being Active (enabled) or Tri-State
(disabled). This capability allows multiple ports to be connected in a multi-drop bus and selectively polled.
RS-485 allows cable lengths up to 4000 feet and data rates up to 10 Megabits per second. The signal levels
for RS-485 are the same as those defined by RS-422. RS-485 has electrical characteristics that allow for 32
drivers and 32 receivers to be connected to one line. This interface is ideal for multi-drop or network
environments. RS-485 tri-state driver (not dual-state) will allow the electrical presence of the driver to be
removed from the line. Only one driver may be active at a time and the other driver(s) must be tri-stated.
RS-485 can be cabled in two ways, two wire and four wire mode. Two wire mode does not allow for full
duplex communication and requires that data be transferred in only one direction at a time. For half-duplex
operation, the two transmit pins should be connected to the two receive pins (Tx+ to Rx+ and Tx- to Rx-).
Four wire mode allows full duplex data transfers. RS-485 does not define a connector pin-out or a set of
modem control signals. RS-485 does not define a physical connector.

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Appendix D –Ground Loop Phenomenon
What is Ground Loop?
Ground loop Phenomenon occurs when two (or more) pieces of equipment are connected with a common
ground and a different ground potential exists at each location. This current can cause the connected
equipment to experience noise that in turn causes data transmission errors. In the extreme this ground
current can cause equipment malfunction or even destruction.
Cabling Recommendations
When connecting the SeaLINK+485I in an RS-485 network, care should be taken that both ends of the
network are not isolated from ground (see Figure 4). This “floating” ground condition could cause
capacitive or inductive coupling of voltages that will cause a break down in the DC to DC converter circuit
or in the opto-isolator circuit. This condition will cause data errors and possibly destruction of the receiver
circuit.
Figure 4 - SeaLINK+485I cabling sample
A B
Isolation
Barrier
DATA+
DATA-
Ground
Isolated
Adapter
Non
Isolated
Adapter

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Appendix E –Asynchronous Communications
Serial data communications implies that individual bits of a character are transmitted consecutively to a
receiver that assembles the bits back into a character. Data rate, error checking, handshaking, and
character framing (start/stop bits) are pre-defined and must correspond at both the transmitting and
receiving ends.
Asynchronous communications is the standard means of serial data communication for PC compatibles
and PS/2 computers. The original PC was equipped with a communication or COM: port that was designed
around an 8250 Universal Asynchronous Receiver Transmitter (UART). This device allows asynchronous
serial data to be transferred through a simple and straightforward programming interface. A start bit,
followed by a pre-defined number of data bits (5, 6, 7, or 8) defines character boundaries for asynchronous
communications. The end of the character is defined by the transmission of a pre-defined number of stop
bits (usually 1, 1.5 or 2). An extra bit used for error detection is often appended before the stop bits.
Asynchronous Communications Bit Diagram
This special bit is called the parity bit. Parity is a simple method of determining if a data bit has been lost
or corrupted during transmission. There are several methods for implementing a parity check to guard
against data corruption. Common methods are called (E)ven Parity or (O)dd Parity. Sometimes parity is not
used to detect errors on the data stream. This is referred to as (N)o parity. Because each bit in
asynchronous communications is sent consecutively, it is easy to generalize asynchronous
communications by stating that each character is wrapped (framed) by pre-defined bits to mark the
beginning and end of the serial transmission of the character. The data rate and communication
parameters for asynchronous communications must be the same at both the transmitting and receiving
ends. The communication parameters are baud rate, parity, number of data bits per character, and stop bits
(i.e., 9600, N, 8, 1).

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Appendix F –Silk-Screen
3.28in
2.09in
1.39in

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Appendix G –Compliance Notices
Federal Communications Commission (FCC) Statement
This equipment has been tested and found to comply with the limits for Class A digital
device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide
reasonable protection against harmful interference when the equipment is operated in a
commercial environment. This equipment generates, uses, and can radiate radio frequency
energy and, if not installed and used in accordance with the instruction manual, may cause
harmful interference to radio communications. Operation of this equipment in a residential
area is likely to cause harmful interference in such case the user will be required to correct
the interference at the user’s expense.
EMC Directive Statement
Products bearing the CE Label fulfill the requirements of the EMC directive (89/336/EEC)
and of the low-voltage directive (73/23/EEC) issued by the European Commission. To
obey these directives, the following European standards must be met:
•EN55022 Class B - “Limits and methods of measurement of radio interference
characteristics of information technology equipment”
•EN55024 –“Information technology equipment Immunity characteristics Limits
and methods of measurement”.
This is a Class B Product. In a domestic environment, this product may cause radio interference in
which case the user may be required to take adequate measures to prevent or correct the
interference.
Always use cabling provided with this product if possible. If no cable is provided or if an alternate
cable is required, use high quality shielded cabling to maintain compliance with FCC/EMC
directives.

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Warranty
Sealevel's commitment to providing the best I/O solutions is reflected in the Lifetime Warranty that is
standard on all Sealevel manufactured I/O products. We are able to offer this warranty due to our control
of manufacturing quality and the historically high reliability of our products in the field. Sealevel products
are designed and manufactured at its Liberty, South Carolina facility, allowing direct control over product
development, production, burn-in and testing. Sealevel achieved ISO-9001:2015 certification in 2018.
Warranty Policy
Sealevel Systems, Inc. (hereafter "Sealevel") warrants that the Product shall conform to and perform in
accordance with published technical specifications and shall be free of defects in materials and
workmanship for the warranty period. In the event of failure, Sealevel will repair or replace the product at
Sealevel's sole discretion. Failures resulting from misapplication or misuse of the Product, failure to adhere
to any specifications or instructions, or failure resulting from neglect, abuse, accidents, or acts of nature
are not covered under this warranty.
Warranty service may be obtained by delivering the Product to Sealevel and providing proof of purchase.
Customer agrees to ensure the Product or assume the risk of loss or damage in transit, to prepay shipping
charges to Sealevel, and to use the original shipping container or equivalent. Warranty is valid only for
original purchaser and is not transferable.
This warranty applies to Sealevel manufactured Product. Product purchased through Sealevel but
manufactured by a third party will retain the original manufacturer's warranty.
Non-Warranty Repair/Retest
Products returned due to damage or misuse and Products retested with no problem found are subject to
repair/retest charges. A purchase order or credit card number and authorization must be provided in order
to obtain an RMA (Return Merchandise Authorization) number prior to returning Product.
How to obtain an RMA (Return Merchandise Authorization)
If you need to return a product for warranty or non-warranty repair, you must first obtain an RMA number.
Please contact Sealevel Systems, Inc. Technical Support for assistance:
Available Monday –Friday, 8:00AM to 5:00PM EST
Phone [phone]
Email [e-mail]
Trademarks
Sealevel Systems, Incorporated acknowledges that all trademarks referenced in this manual are the
service mark, trademark, or registered trademark of the respective company.