SeaLevel ISO COMM2.cPCI User manual

1
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
ISO COMM2.cPCI™
User Manual | 7903

2
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Contents
CONTENTS...........................................................................................................................................................2
BEFORE YOU GET STARTED ...............................................................................................................................4
CARD SETUP ........................................................................................................................................................5
INSTALLATION .................................................................................................................................................... 9
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..............................................................................................16
APPENDIX E – ASYNCHRONOUS COMMUNICATIONS ..................................................................................17
APPENDIX F – SILK SCREEN ............................................................................................................................18
APPENDIX G – COMPLIANCE NOTICES ..........................................................................................................19
WARRANTY ........................................................................................................................................................20

3
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Introduction
The Sealevel Systems ISO COMM+2.cPCI is a two channel isolated cPCI Bus serial I/O adapter. Utilizing
the Exar 16C850 UART with its industry leading 128 byte FIFOs, it provides two field selectable
RS232/422/485 serial ports supporting data rates up to 460.8K bps (RS-422/485).
Configure both ports as RS232 for standard serial COM: port requirements. Choose the RS-422 mode for
long distance device connections up to 5000ft. where noise immunity and high data integrity are
essential. Select RS-485 and capture data from multiple peripherals in a RS485 multidrop network. Up to
31 RS-485 devices can be connected to each port to automate your data collection. You can even mix the
ports in any of the interface combinations to provide maximum flexibility to your application. Optional
Terminal Block adapters are available to simplify field-wiring connections.
In both RS-232 and RS-422 modes, the card works seamlessly with the standard operating system serial
driver. In RS-485 mode, our special auto-enable feature allows the RS485 ports to be viewed by the
operating system as a COM: port. This allows the standard COM: driver to be utilized for RS485
communications. Our on-board hardware automatically handles the RS-485 driver enable.

4
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Before You Get Started
What’s Included
The ISO COMM+2.cPCI is shipped with the following items. If any of these items are missing or damaged,
please contact Sealevel for replacement.
•ISO COMM+2.cPCI Serial I/O Adapter
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.

5
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Card Setup
Electrical Interface Selection
Each port on the ISO COMM+2.cPCI has the ability to be used as RS-232, RS-422 or RS-485. This is
selectable via two DIP-switches, SW1 & SW2. Please use the following examples to configure your
adapter.
Figure 1- RS-232
Figure 2 - RS-422
Figure 3 - RS-485, 4-Wire with Echo
Figure 4 - RS-485 2-Wire with Echo
Figure 5 - RS-485, 2-wire without Echo
1234567
ON
OFF
8910
1 2 3 T P P L L E
RS-232
1 2 3 4 5 6 7
ON
OFF
8 9 10
1 2 3 T P P L L E
RS-422
1 2 3 4 5 6 7
ON
OFF
8 9 10
1 2 3 T P P L L E
4-Wire
RS-485
W/Echo
1 2 3 4 5 6 7
ON
OFF
8 9 10
1 2 3 T P P L L E
2-Wire
RS-485
W/Echo
1 2 34 5 6 7
ON
OFF
8 9 10
1 2 3 T P P L L E
2-Wire
RS-485
NO Echo

6
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
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 1K-ohm pull-
up/pull-down combination that biases the receiver inputs. Switches SW1 and SW2 allow the user to
customize this interface to their specific requirements. Each switch position corresponds to a specific
portion of the interface. If multiple ISO COMM+2.cPCI adapters are configured in a RS-485 network, only
the boards on each end should have jumpers T, P & P ON. Refer to the following table for each position’s
operation:
Name
Function
T Adds or removes the 120 ohm termination.
P
Adds or removes the 1K ohm pull-down resistor in the RS-422/RS-
485 receiver circuit (Receive data only).
P
Adds or removes the 1K ohm pull-up resistor in the RS-422/RS-
485 receiver circuit (Receive data only).
L Connects the TX+ to RX+ for RS-485 two wire operation.
L Connects the TX- to RX- for RS-485 two wire operation.
RS-485 Enable Modes
RS-485 is ideal for multi-drop or network environments. RS-485 requires a tri-state driver that will allow
the electrical presence of the driver to be removed from the line. The driver is in a tri-state or high
impedance condition when this occurs. Only one driver may be active at a time and the other driver(s)
must be tri-stated. The output modem control signal Request To Send (RTS) is typically used to control
the state of the driver. Some communication software packages refer to RS-485 as RTS enable or RTS
block mode transfer.
One of the unique features of the ISO COMM+2.cPCI is the ability to be RS-485 compatible without the
need for special software or drivers. This ability is especially useful in Operating Systems where the lower
level I/O control is abstracted from the application program. This ability means that the user can
effectively use the ISO COMM+2.cPCI in an RS-485 application with existing (i.e. standard RS-232)
software drivers.
Switches SW3 and SW4 are used to control the RS-485 mode functions for the driver circuit. The
selections are ‘RTS’ enable (silk-screen ‘RT’ switch position 4) or ‘Auto’ enable (silk-screen ‘AT’ switch
position 3). The ‘Auto’ enable feature automatically enables/disables the RS-485 interface. The ‘RTS’
mode uses the ‘RTS’ modem control signal to enable the RS-485 interface and provides backward
compatibility with existing software products.
The RS-485 ‘Echo’ is the result of connecting the receiver inputs to the transmitter outputs. Every 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) or it can confuse the system if the software does
not. Position 9 of SW1 and SW2 is used to control the RS-485 enable/disable functions for the receiver
circuit. To select the ‘No Echo’ mode place switch position 9 to the ‘On’ position (see Figure 5).

7
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Figure 6 - RS-485 Enable modes
Clock Modes
The ISO COMM+2.cPCI employs a unique clocking option that allows the end user to select from divide
by 4 and divide by 1 clocking modes. These modes are selected at switches SW3 & SW4.
To select the Baud rates commonly associated with COM: ports (i.e. 2400, 4800, 9600, 19.2, … 115.2K
Bps) set switch position 2 to the ‘On’ position (silk-screen D4). To select the maximum data rate (460.8K
bps) set switch position 1 to the ‘On’ position (silk-screen D1).
Figure 7 - Clocking Modes
1 2 3 4
ON
OFF
D
1
D
4
A
T
R
T
1 2 3 4
ON
OFF
SW3
SW4
RS-232/422
Default
1234
ON
OFF
D
1
D
4
A
T
R
T
1234
ON
OFF
SW3
SW4
RS-485
Auto
Enabled
1234
ON
OFF
D
1
D
4
A
T
R
T
1234
ON
OFF
SW3
SW4
Divide by
1 mode
Divide by
4 mode

8
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Baud Rates and Divisors for the ‘Div1’ Mode
The following table shows some common data rates and the rates you should choose to match them if
using the adapter in the ‘Div1’ mode.
For this Data Rate
Choose this Data Rate
1200 bps
300 bps
2400 bps 600 bps
4800 bps 1200 bps
9600 bps 2400 bps
19.2K bps 4800 bps
57.6 K bps 14.4K bps
115.2 K bps 28.8K bps
230.4K bps 57.6K bps
460.8K bps 115.2K bps
If your communications package allows the use of Baud rate divisors, choose the appropriate divisor
from the following table:
For this Data Rate
Choose this Divisor
1200 bps
384
2400 bps
192
4800 bps 96
9600 bps 48
19.2K bps 24
38.4K bps 12
57.6K bps 8
115.2K bps 4
230.4K bps 2
460.8K bps
1

9
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Installation
Operating System Installation
For Windows Users
Begin by locating, selecting and installing the correct software from the Sealevel software driver database.
Other Operating Systems
Refer to the appropriate section of the Serial Utilities Software.
System Installation
The ISO COMM+2.cPCI can be installed in any of the PCI expansion slots and contains several jumper
straps for each port that must be set for proper operation.
1. Turn off PC power. Disconnect the power cord.
2. Remove the PC case cover.
3. Locate an available PCI slot and remove the blank metal slot cover.
4. Gently insert the ISO COMM+2.cPCI into the slot. Make sure that the adapter is seated properly.
5. Replace the screw.
6. Replace the cover.
7. Connect the power cord.
Installation is complete.

10
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Technical Description
The Sealevel Systems ISO COMM+2.cPCI provides a cPCI interface adapter with 2 isolated asynchronous
serial ports providing a versatile interface, field selectable as RS-232 for modems, printers and plotters, as
well as RS-422/485 for industrial automation and control applications. Isolation is important in
installations where the equipment being connected to the PC is either far from the PC, or on a different
power transformer circuit. Ground loop current is a commonly neglected and misunderstood
phenomenon that leads to data loss and the destruction of communications interfaces.
The ISO COMM+2.cPCI utilizes the 16C850 UART. This chip features programmable baud rates, data
format, interrupt control and industry leading 128-byte FIFOs.
Connector Pin Assignments
RS-232
Name Pin # Mode
TD Transmit Data 3 Output
RTS Request To Send
7
Output
GND Ground 5
RD Receive Data 2 Input
CTS Clear To Send 8 Input
These assignments meet EIA/TIA/ANSI-574 DTE for DB-9 type connectors.
RS-422/485
Signal Name Pin # Mode
GND
Ground
5
TX +
Transmit Data Positive
4
Output
TX- Transmit Data Negative 3 Output
RTS+ Request To Send Positive 6 Output
RTS- Request To Send Negative 7 Output
RX+ Receive Data Positive 1 Input
RX-
Receive Data Negative
2
Input
CTS+
Clear To Send Positive
9
Input
CTS- Clear To Send Negative 8 Input

11
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
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 375 mA
Mean Time Between Failures (MTBF)
Greater than 150,000 hours. (Calculated)
Physical Dimensions
The adapter conforms to the requirements of a 3U Adapter as set forth by the PCI SIG.

12
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Appendix A – Troubleshooting
Sealevel Software is supplied with the Sealevel Systems adapter and will be used in the troubleshooting
procedures. By using this diskette and following these simple steps, most common problems can be
eliminated without the need to call Technical Support.
1. 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.
2. 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.
3. Make sure the Sealevel Systems adapter is securely installed in a motherboard slot.
4. For Windows95/98/ME/NT/2000/XP, 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.
5. Always use the Sealevel software when troubleshooting a problem. This will eliminate any software
issues from the equation.

13
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Appendix B – How To Get Assistance
Please refer to Troubleshooting Guide prior to calling Technical Support.
1. Begin by reading through the Trouble Shooting Guide in Appendix A. If assistance is still needed
please see below.
2. 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.
3. 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.
4. 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.
5. 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.

14
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Appendix C – Electrical Interface
RS-232
Quite possibly the most widely used communication standard is RS-232. This implementation has been
defined and revised several times and is often referred to as RS-232 or EIA/TIA-232. The IBM PC
computer defined the RS-232 port on a 9 pin D sub connector and subsequently the EIA/TIA approved this
implementation as the EIA/TIA-574 standard. This standard is defined as the 9-Position Non-Synchronous
Interface between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial
Binary Data Interchange. Both implementations are in wide spread use and will be referred to as RS-232 in
this document. RS-232 is capable of operating at data rates up to 20 Kbps at distances less than 50 ft.
The absolute maximum data rate may vary due to line conditions and cable lengths. RS-232 is a single
ended or unbalanced interface, meaning that a single electrical signal is compared to a common signal
(ground) to determine binary logic states. The RS-232 and the EIA/TIA-574 specification define two types
of interface circuits, Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment (DCE). The
ISO COMM+2.cPCI is a DTE device.
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.

15
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
RS-485
RS-485 is backwardly compatible with RS-422; however, it is optimized for partyline 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.

16
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Appendix D – Ground Loop Phenomenon
What is Ground Loop?
Ground loop Phenomenon occurs when two (or more) pieces of equipment are connected together 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 Requirements
When connecting the ISO COMM+2.cPCI in a RS-485 network, care should be taken that both ends of the
network are not isolated from ground (see Figure 8). This “floating” ground condition could cause the
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.
AB
Isolation
Barrier
DATA+
DATA-
Ground
Isolated
Adapter
Non
Isolated
Adapter
Figure 8 – ISO COMM+2.cPCI cabling example

17
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Appendix E – Asynchronous Communication
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.
Figure 9 - 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 refereed 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).

18
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
Appendix F – Silk Screen

19
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
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 users 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”.
This is a Class A 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.

20
© Sealevel Systems, Inc. 7903 Manual | SL9072 7/2021
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.