SEALEVEL 3547 PC/104 Serial Interface User Manual
- June 5, 2024
- SEALEVEL
Table of Contents
- SEALEVEL 3547 PC/104 Serial Interface
- Introduction
- Features
- Before You Get Started
- Adapters and Converters
- PC/104 Adapter Kits
- IRQ Selection
- Interrupt Modes
- Baud Rates, Continued
- Programmable Features
- Installation & Configuration
- Hardware Installation
- Technical Specifications
- Appendix
- Warranty
- References
- Read User Manual Online (PDF format)
- Download This Manual (PDF format)
SEALEVEL 3547 PC/104 Serial Interface
Introduction
The 3547 PC/104 serial interface provides four serial ports with 1,500VDC port-to-port isolation that protect the host system from ground loops and voltage transients that are common in remote installations and industrial environments. For maximum versatility without opening the PC/104 stack, each port is software configurable for full-duplex (4-Wire) RS-422 or RS-485. Half duplex (2-Wire) RS-485 mode is also supported. The ‘auto-enable’ circuit automatically handles the RS-485 driver, which eliminates the risk of bus contention and data corruption. With the driver controlled in hardware, the RS-485 ports are treated as standard serial COM ports by the operating system.
Features
- 1,500VDC port-to-port isolation
- Each port is software configurable for 4-wire RS-422/485 or 2-wire RS-485
- 16954 buffered UART with 128-byte FIFOs
- Automatic hardware RS-485 enable/disable
- UART support for 9-bit protocol
- Data rates to 921.6K bps
- Jumpers on each port for suppressing ECHO
- Four 10-pin vertical header connectors
- Extended temperature range available (-40°C – +85°C)
Before You Get Started
The 3547 is shipped with the following items. If any of these items are missing or damaged, please contact Sealevel for replacement.
- C4-104.485+1 (Item# 3547) – PC/104 RS-422, RS-485 (Software Selectable) Isolated Serial Interface
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.
Optional Items
Depending upon your application, you are likely to find one or more of the following items useful with the 3547. All items can be purchased from our website (www.sealevel.com) or by calling our sales team at 864-843-4343.
Cables
10-Pin IDC Ribbon Cable to DB9M (Item# CA152)
The CA152 allows connects to the 10-pin header on PC/104 boards and provides a
DB9M connector that can be panel mounted in an enclosure. This cable is eight
inches in length.
DB9F to DB9M Extension Cable (Item# CA127)
The CA127 allows users to extend a DB9 cable up to six feet. The connectors
are pinned one-to-one, so the cable is compatible with any device or cable
with DB9 connectors.
DB9F (RS-422) to DB25M (RS-530) Cable (Item# CA176)
The CA176 allows users to convert any Sealevel RS-422 DB9 Male asynchronous
adapter to an RS-530 DB25 Male pinout. This cable is ten inches in length.
DB9F to DB9F – 207M SMPTE Cable (Item# CA190)
The CA190 connects any Sealevel DB9 RS-422 device to a Sony (or compatible)
207M (SMPTE) 9-pin connector. This cable is 72” in length.
Terminal Blocks
Terminal Block Kit (Item# KT105)
The KT105 terminal block kit breaks out a DB9 connector to 9 screw
terminals to simplify field wiring of serial connections including RS-422 and
RS-485 networks. The kit includes one DB9 terminal block (Item# TB05) and one
DB9M to DB9F 72” extension cable (Item# CA127).
Terminal Block – DB9F to 9 Screw Terminals (Item# TB05)
The TB05 terminal block breaks out a DB9 connector to 9 screw terminals to
simplify field wiring of serial connections including RS-422 and RS-485
networks. The TB05 is designed to connect directly to Sealevel DB9 serial
cards or any cable with a DB9M connector.
Adapters and Converters
DB9F to RJ45 Modular Adapter (Item# RJ9S8)
The RJ9S8 is a DB9 female to RJ45 adapter. It can be configured without
tools, and it is an excellent choice for using available infrastructure
wiring. DB9F (RS-422) to DB9F Converter (Item# DB103)
The DB103 is designed to convert a Sealevel DB9 male RS-422 connector to a
DB9 female pinout compatible with AC24AT and AC422AT Opto 22 ISA bus cards.
PC/104 Adapter Kits
PC/104 to CompactFlash Adapter (Item# CF104)
The CF104 allows users to easily add a CompactFlash memory card with an IDE
interface to a PC/104 stack. The CF104 includes an adapter board built into
the PC/104 form factor. The arrangement of mounting holes at the corners
allows the board to be rotated and mounted 180 degrees on the long axis.
PC/104 to 2.5” Hard Drive Adapter (Item# HD104)
The HD104 allows users to easily add an optional 2.5” hard drive with an
IDE interface to a PC/104 stack. The HD104 includes an adapter board built
into the PC/104 form factor and offers two different mounting options. Card
Setup
The 3547 contains a single 4 position DIP-Switch (labeled SW1) that provides
the address selection for the adapter and a jumper strip (labeled E5)
providing the IRQ selection for the adapter.
Address Selection
Each port on the 3547 occupies sixteen consecutive I/O locations. The DIP
switch is used to set the base address for the serial ports and the following
table shows the addressing options available. If different address options are
required, please contact Sealevel Systems Technical Support about a custom PAL
option.
SW1-1 | SW1-2 | SW1-3 | Port 1 | Port 2 | Port 3 | Port 4 |
---|---|---|---|---|---|---|
OFF | OFF | ON | 300 | 310 | 320 | 330 |
OFF | ON | OFF | 400 | 410 | 420 | 430 |
OFF | ON | ON | 500 | 510 | 520 | 530 |
ON | OFF | OFF | 600 | 610 | 620 | 630 |
ON | OFF | ON | 1500 | 1510 | 1520 | 1530 |
ON | ON | OFF | 3220 | 3230 | 3240 | 3250 |
ON | ON | ON | 4220 | 4230 | 4240 | 4250 |
The fourth switch, ‘S’ on the DIP switch is used to allow a shared interrupt
between multiple PC/104 adapters. Reference the Interrupt Modes section on the
following page for additional information.
An image and a drawing of the DIP switch (SW1) are shown below.
Port Enable/Disable
All four ports on the 3547 can be disabled by setting switches 1, 2, and 3 on SW1 to the ‘Off’ position. The ports are enabled when a valid I/O selection is made. If the adapter is disabled, be sure to disable the interrupt request by removing the IRQ jumper from E5.
IRQ Selection
The 3547 has an interrupt selection jumper (labeled E5) for all four of the ports. Be sure to set the interrupt required by your application prior to installation. Consult the manual included with your software application to determine the proper setting. The jumpers located at E5 are used to select the appropriate interrupt for the adapter. The jumper for the 1K pull-down resistor (labeled ‘PD’) on E5 connects the resistor to the interrupt line to keep the line from floating. This jumper must be connected when either a single board or multiple boards on different interrupts are in use. In situations where multiple cards are sharing interrupts, only one board in the group should have the PD resistor connected. An image and a drawing of E5 are included below.
Interrupt Modes
Shared interrupt mode is used to allow more than one PC/104 board to share a single IRQ. The switch position ‘S’ on DIP switch SW1, when moved to the ‘on’ position, selects the shared interrupt mode for the adapter. When configuring two or more PC/104 adapters, the following criteria must be met:
- The ‘S’ switch on DIP switch SW1 should be set to ‘on’ for each adapter that will share an interrupt.
- The IRQ jumpers (E5) on each adapter need to be set to the same IRQ.
- Each board must be set to a different address. For example, if two boards are used, the addresses might be set as follows:
DIP switch:| 1| 2| 3| S
---|---|---|---|---
Board 1:| Off| Off| On| On
Board 2:| Off| On| Off| On
Refer to the Address Selection section for additional information.
- Only one card in the group should have the pull-down (PD) on E5 activated. The image below shows what the DIP switch and jumper settings would look like for two PC/104 boards installed in the same computer. In situations where PC/104 boards do not need to share interrupts, make sure that the switch position ‘S’ on DIP switch SW1 is moved to the ‘off’ position. In addition, the IRQ jumpers on E5 should be set to different interrupts for each board.
Clock Modes
The 3547 utilizes a 14.7456 MHz oscillator. This is eight times faster than a standard COM: port oscillator, which typically is 1.8432 MHz. This allows the adapter to achieve a maximum data rate of 921.6Kbps. The following sections outline the baud rate calculations and instructions for achieving your desired baud rate.
Oscillator Value (Aliasing)
If Windows operating system used, the oscillator value (14.7456 MHz) should be
entered into the ‘Advanced’ tab in the Device Manager. This is usually done
automatically when the Sealevel SeaCOM driver is loaded.
If you are using a Windows operating system, the Sealevel SeaCOM driver will
typically set the oscillator value automatically. To set the value manually,
open the Windows Device Manager and click on ‘Ports (COM & LPT).’ Locate the
port number for your device and right click to select ‘Properties.’ In the
Properties window, open the ‘Port Settings’ tab and click on the ‘Advanced’
button. Enter the oscillator value (14.7456). If using an operating system
other than Windows, you may need to manually enter the oscillator value. If
you do not do this, all data rates will be eight times the selected rate. For
example, if a data rate of 19.2Kbps is selected, the actual data rate will be
153.6Kbps. Refer to Baud Rates section on the following page for appropriate
settings and divisors.
Baud Rates
The SeaCOM driver for Windows will automatically set the correct data rate for
your card. However, if you are using an operating system other than Windows,
the data rate will be eight times the selected rate. You may need to set the
data rate manually in order to configure the card to run at the desired rate.
If your operating system does not allow you to manually set the oscillator
value on your card, you will need to select a data rate that is eight times
less than the desired rate. The table below includes some common data rates.
You can also choose additional baud rates by dividing the baud rate you wish
to achieve by eight. The resulting number will be the baud rate you will need
to tell your system in order to cause your card to run at the desired rate.
Baud Rates, Continued
For this Data Rate | Choose this Data Rate |
---|---|
1200 bps | 150 bps |
2400 bps | 300 bps |
4800 bps | 600 bps |
9600 bps | 1200 bps |
19.2K bps | 2400 bps |
38.4 K bps | 4800 bps |
115.2 K bps | 14.4K bps |
230.4K bps | 28.8K bps |
460.8K bps | 57.6 K bps |
921.6K bps | 115.2 K bps |
In situations where you are communicating with the hardware directly, or using
software that requires a divisor, you will need to select a divisor that will
cause your card to run at the desired rate. The table below includes some
common divisors.
You can also select other divisors by diving 921.6K by your intended baud
rate. The resulting number will be the divisor that you will need to give your
system for your card to run at the desired rate.
For this Data Rate | Choose this Divisor |
---|---|
1200 bps | 768 |
2400 bps | 384 |
4800 bps | 192 |
9600 bps | 96 |
19.2K bps | 48 |
38.4K bps | 24 |
57.6K bps | 16 |
115.2K bps | 8 |
230.4K bps | 4 |
460.8K bps | 2 |
921.6K bps | 1 |
Programmable Features
Each of the ports on the 3547 can be individually software configured as an
RS-422 or RS-485 interface. Electrical interface selection is handled via the
‘Control’ port (Base + 15) or via the Sealevel SeaCOM driver interface in
Windows Device Manager.
Power up default = 2-wire RS-485 with RTS
D2 | D1 | D0 | Mode |
---|---|---|---|
X | X | 0 | RS-422 |
0 | 0 | 1 | RS-485, 4-wire, RTS auto-enable |
0 | 1 | 1 | RS-485, 4-wire, DTR auto-enable |
1 | 0 | 1 | RS-485, 2-wire, RTS auto-enable |
1 | 1 | 1 | RS-485, 2-wire, DTR auto-enable |
D0 = RS-422/485; D1 = RTS/DTR auto-enable; D2 = 2-wire/4-wire
Line Termination
Typically, each end of the RS-485 bus must have line-terminating resistors (RS-422 terminates at the receive end only). A 120-ohm resistor is across each RS-422/485 input in addition to a 510-ohm pull-up/pull-down combination that biases the receiver inputs. If multiple 3547 adapters are configured in an RS-485 network, only the boards on each end should have the termination in place. If you have additional questions on how to remove this termination, contact Technical Support at 864-843-4343.
RS-485 ‘Echo’
The RS-485 ‘Echo’ is the result of connecting the receiver inputs to the transmitter outputs. Each time a character is transmitted; it is also received. This can be beneficial if the software can handle echoing (i.e., using received characters to throttle the transmitter), but it can also confuse the system if the software cannot support echoing. Echo is controlled on a per-port basis by jumpers E1, E2, E3, and E4. When a jumper is in place, Echo is suppressed. Similarly, Echo can be enabled by removing a jumper from the appropriate port. The image below shows jumper E1 located next to P1.
Installation & Configuration
Windows Software Installation
Do not install the adapter in the machine until the software has been fully installed. Only users running Windows 7 or newer should utilize these instructions for accessing and installing the appropriate driver via Sealevel’s website. If you are utilizing an operating system prior to Windows 7, please contact Sealevel by calling 864.843.4343 or emailing support@sealevel.com to receive access to the legacy driver download and installation instructions.
- Begin by locating, selecting, and installing the correct SeaCOM software from Sealevel’s website: SeaCOM Software Overview.
- Select SeaCOM for Microsoft Windows.
- Select SeaCOM for Windows in the Downloads section.
- The setup file will automatically detect the operating environment and install the proper components.
You are now ready to proceed with installing the 3547 in your system. Refer to the following section, Hardware Installation, for details.
Linux Installation
You MUST have “root” privileges to install the software and drivers.
The syntax is case sensitive.
SeaCOM for Linux can be downloaded here: https://www.sealevel.com/support
/software-seacom-linux/. It includes the README and the Serial-HOWTO help files (located at
seacom/dox/howto). This series of files both explains typical Linux serial
implementations and informs the user about Linux syntax and preferred
practices. User can use a program such as 7-Zip to extract the tar.gz file. In
addition, the software selectable interface settings can be accessed by
referencing seacom/utilities/3540mode. For additional software support, please
call Sealevel Systems’ Technical Support,
864-843-4343. Our technical support is
free and available from 8:00 AM – 5:00 PM Eastern Time, Monday through Friday.
For email support contact:
support@sealevel.com. In addition, the software
selectable interface settings can be accessed by referencing
seacom/utilities/3540mode. For additional software support, please call
Sealevel Systems’ Technical Support,
864-843-4343. Our technical support is
free and available from 8:00 AM – 5:00 PM Eastern Time, Monday through Friday.
For email support contact:
support@sealevel.com.
Hardware Installation
Take extreme care when installing the adapter to avoid damaging the PC/104 connector pins. Be sure to follow proper ESD procedures by grounding yourself and the adapter. To install the 3547 into your computer, follow the steps below.
-
Turn off PC power and disconnect the power cord.
-
Remove the case cover (if applicable).
-
Mount the hardware using the nylon stand-offs and/or screws provided to ensure a good mechanical connection. Retain any unused mounting hardware for future expansion.
-
Gently insert the adapter noting proper key orientation of the expansion connector on a PC/104 compatible card. The adapter is keyed per the current PC/104 specification to prevent the adapter from being inserted incorrectly.
-
After the adapter is installed, connect up to four I/O cables to the 10-pin headers at Ports 1 through. These headers are keyed to prevent cables from being installed incorrectly.
The optional CA152 cable is an eight-inch long IDC ribbon cable with a 10-pin connector on one end and a DB9 male connector on the other end. The CA152 can be panel mounted in your enclosure. -
proceed with adding additional PC/104 cards (if applicable) and secure with additional standoffs. If this board is at the top of the PC/104 stack, secure the board with #4-40 machine screws.
-
Replace the cover (if applicable).
-
Connect the power cord and power up the machine. You are now ready to configure the PC/104 adapter to work in your application. Refer to the following section, Hardware Configuration, for details.
Hardware Configuration
Run the ‘Add Hardware’ utility located in the Control Panel. Double click the icon to launch the wizard and follow the prompts.
- Windows will first search for plug and play devices. Windows will be unable to locate the board because it is not plug and play.
- The wizard will ask if you have already installed the hardware, click on ‘yes.’
- When the Installed Hardware List appears, select ‘Add a new hardware device’ at the bottom of the list.
- Windows will ask if you want the system to search for additional devices. Select ‘I want to install the hardware I manually select from a list’ and click on the ‘Next’ button.
- Windows will display a list of common hardware types. Select ‘Show all devices’ and click on ‘Next.’ The system will compile a thorough list of hardware.
- Once the list is compiled, locate the left hand column, and select ‘Sealevel Systems, Inc.’ from the list. Next, locate the right hand column and select ‘C4-104.485+1: PC-104 4 Port RS-422/485 (3547)’ from the list and click ‘Next.’
- Windows will show a warning message that the hardware has not passed Windows logo testing. Click on the ‘Continue anyway’ button. All applications and drivers have been fully tested to maintain the integrity of your operating system. Clicking on ‘Continue anyway’ will not harm your system in any way.
- The Completing Add Hardware wizard will appear. At the bottom of the window, click on the link titled ‘View or change resources for this hardware (advanced).’
- On the Resources page, click on the ‘Set configuration manually’ button. Be sure that the setting you select for the configuration match the settings on your board.
This window will show the default settings for the I/O address and one IRQ. Since Windows cannot detect the settings there may be a conflict with another device or the settings shown may be not the settings you wish to use.
Hardware Configuration, Continued
- To change the settings, choose the appropriate basic configuration number in the ‘Setting Based On’ field to match the card settings.
- In the Resource Settings box, scroll to the bottom of the list and double click on ‘IRQ’ to open the Interrupt Request box.
- In the Value field, select the interrupt that the board is set to. This interrupt will be shared by all four ports.
- Click on ‘Ok’ to close the interrupt request box.
- Click on ‘Ok’ again to close the Resource Settings box and click on ‘Finish’ in the Completing Add Hardware box.
- The computer will prompt you to shut down and reboot the system.
- Once the hardware has been installed, restart your system.
- After the system reboots, the Found New Hardware wizard will appear for each port that you are installing (up to four in this case).
- Click on ‘Install the software automatically’ followed by the ‘Next’ button.
- The warning message stating that the device has not passed Windows logo testing will appear (this is the same message you saw earlier in the process), and you should click on ‘Continue Anyway.’
- Click on ‘Finish.’ Repeat this process for the remaining ports on the card. The installation instructions above are best used with Windows XP. If you are using a different version of Windows, and need additional assistance, contact Technical Support at 864-843-4343. For email support contact: support@sealevel.com.
- To confirm that the drivers have been successfully installed, you can look in the Device Manager under ‘Ports (COM &LPT)’ and each of the ports that you installed should be included on the list with their associated COM numbers.
- In addition, the software selectable settings can be accessed and changed via the ‘Advanced’ tab in the device manager. The ‘Software Selectable Cards’ section allows the electrical interface to be changed between RS-422, RS-485 3-wire, and RS-485 4-wire. For additional information, reference the Programmable Features section of this manual.
Electrical Specifications
The 3547 provides four RS-422/485 software programmable ports from a single
PC/104 adapter. The 3547 utilizes the 16954 UART. This chip supports 9-bit
protocol and features programmable baud rate, data format, interrupt control
and industry leading 128-byte transmit and receive FIFOs.
Connector Pinouts
10-pin Pinout
This board uses a 10-pin 0.1” box header for each of its four ports. This
pinout for each port is included below.
Connector Pinouts, Continued
DB9 Pinout
The optional CA152 cable is an eight inch long IDC ribbon cable with a 10-pin
connector on one end and a DB9 male connector on the other. This cable
provides the standard Sealevel Systems DB9 pinout for RS-422/485. This pinout
is shown below.
Technical Specifications
Environmental Specifications
Specification | Operating | Storage |
---|---|---|
Temperature Range | 0º to 50º C (32º to 122º F) | -50º to 105º C (-58º to |
221º 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.
Physical Dimensions
Length | 3.550 inches (9.017 cm) |
---|---|
Width | 3.775 inches (9.589 cm) |
Height (top) | 0.435 inches (1.105 cm) |
Height (bottom) | 0.100 inches (0.254 cm) |
Appendix
A – Troubleshooting
The adapter should provide years of trouble-free service. However, in the event that device appears to not be functioning incorrectly, the following tips can eliminate most common problems without the need to call Technical Support.
-
Identify all I/O adapters currently installed in your system. This includes your on-board serial ports, controller cards, sound cards etc. The I/O addresses used by these adapters, as well as the IRQ (if any) should be identified.
-
Configure your Sealevel Systems adapter so that there is no conflict with currently installed adapters. No two adapters can occupy the same I/O address. For more information, refer to the Address Selection portion of this manual.
-
Many other adapters do not allow the sharing of IRQs. Try the Sealevel Systems adapter with a unique IRQ.
Make sure the adapter is securely installed. -
For Windows operating systems, the diagnostic tool ‘WinSSD’ is installed in the SeaCOM folder on the Start Menu during the setup process. First find the ports using the Device Manager, then use ‘WinSSD’ to verify that the ports are functional.
-
Remember if a “No Echo” mode is selected, a data loopback cannot be accomplished.
-
Always use the Sealevel Systems diagnostic software when troubleshooting a problem. This will eliminate any software issues from the equation.
If these steps do not solve your problem, please call Sealevel Systems’ Technical Support, 864-843-4343. Our technical support is free and available from 8:00 AM to 5:00 PM Eastern Time Monday through Friday. For email support contact support@sealevel.com..
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.htm.
- Sealevel Systems maintains a Home page on the Internet. Our home page address is www.sealevel.com. The latest software updates, and newest manuals are available via our FTP site that can be accessed from our home page.
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
864-843-4343. For email support contact
support@sealevel.com.
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.
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 one 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 pinout or a set of modem control signals.
RS-485 does not define a physical connector.
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.
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 have to 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).
Silk-Screen – 3547
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 his own 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 A – “Limits and methods of measurement of radio interference characteristics of information technology equipment”
• EN55024 – “Information technology equipment Immunity characteristics Limits and methods of measurement”.
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:
References
- Sealevel - I/O & Computing Products, Engineering and Manufacturing
- FAQs - Sealevel
- Sealevel - I/O & Computing Products, Engineering and Manufacturing
- SeaCOM Software Overview - Sealevel
- Software: SeaCOM - Linux - Sealevel
- Software: SeaCOM - Windows - Sealevel
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