SeaLevel ACB II 3061 User manual

ACB II™
USER’S MANUAL
Part Number 3061
Sealevel Systems, Inc Phone: [phone]
P.O. Box 830 Fax: [phone]
Liberty, SC 29657 USA www.sealevel.com

Contents
INTRODUCTION............................................................................................1
OVERVIEW......................................................................................1
WHAT’S INCLUDED ........................................................................1
FACTORY DEFAULT SETTINGS ........................................................1
CARD SETUP ................................................................................................2
ADDRESS SELECTION......................................................................2
INTERFACE SELECTION ...................................................................3
RS-232 ........................................................................................3
RS-422 ........................................................................................3
RS-485 ........................................................................................3
IRQ SELECTION..............................................................................3
DMA CHANNEL SELECTION (HEADER E3).....................................4
DMA ENABLE (HEADER E7)..........................................................4
MISCELLANEOUS I/O PIN SELECTION (HEADER E4) .......................5
Input Pins....................................................................................5
Output Pins .................................................................................5
INSTALLATION.............................................................................................6
SYSTEM INSTALLATION ..................................................................6
TECHNICAL DESCRIPTION ..........................................................................7
FEATURES.......................................................................................7
PROGRAMABLE BAUD RATE GENERATOR ......................................7
CONNECTOR PIN ASSIGNMENTS .....................................................8
RS-422 ........................................................................................8
RS-232 ........................................................................................8
SPECIFICATIONS..........................................................................................9
ENVIRONMENTAL SPECIFICATIONS .................................................9
MANUFACTURING...........................................................................9
POWER CONSUMPTION ...................................................................9
MEAN TIME BETWEEN FAILURES (MTBF).....................................9
PHYSICAL DIMENSIONS ..................................................................9
APPENDIX A - TROUBLESHOOTING..........................................................10
APPENDIX B - HOW TO GET ASSISTANCEERROR! BOOKMARK NOT DEFINED.
APPENDIX C - ELECTRICAL INTERFACE ..................................................13
RS-232.........................................................................................13
RS-422.........................................................................................13

RS-485 ........................................................................................ 14
APPENDIX D - DIRECT MEMORY ACCESS ............................................... 15
APPENDIX E - ASYNCHRONOUS AND SYNCHRONOUS COMMUNICATIONS16
ASYNCHRONOUS COMMUNICATIONS ........................................... 16
SYNCHRONOUS COMMUNICATIONS.............................................. 18
APPENDIX F - SILK-SCREEN .................................................................... 20
APPENDIX G - COMPLIANCE NOTICES .................................................... 21
FEDERAL COMMUNICATIONS COMMISSION STATEMENT.............. 21
EMC DIRECTIVE STATEMENT...................................................... 21
WARRANTY ............................................ ERROR! BOOKMARK NOT DEFINED.
Figures
Figure 1 - DIP-Switch Illustration ........................................................... 2
Figure 2 - Header E1 & E9, IRQ Selection (Shown in Factory Default)3
Figure 3 - Header E3 DMA Selection ....................................................... 4
Figure 4 - Header E7 DMA Enable (Factory Default) ........................... 4
Figure 5 - Header E4 (Shown in Factory Default).................................. 5
Figure 6 - Asynchronous Communications Bit Diagram ..................... 17
Figure 7 - Synchronous Communications Bit Diagram ....................... 18
© Sealevel Systems, Inc.
SL9081 Revision 7/2006
Sealevel Systems, Incorporated. All rights reserved.

Introduction
Sealevel Systems ACB-II Page 1
Introduction
Overview
The Sealevel ACB-II Advanced Communications Board provides the PC
with one high speed sync/async port. The ACB-II can be used in a variety
of sophisticated communications applications such as SDLC, HDLC, X.25,
and High Speed Async.
What’s Included
The ACB-II is shipped with the following items. If any of these items are
missing or damaged, contact the supplier.
• (1) ACB-II Advanced Communications Board
• Sealevel Software
• RS-232 Interface Chips (1488 & 1489)
Factory Default Settings
The ACB-II factory default settings are as follows:
Base Address DMA Channel IRQ Electrical Specification
238 3 5 RS-422
To install the ACB-II using factory default settings, refer to Installation on
page 6.
For your reference, record installed ACB-II settings below:
Base Address DMA Channel IRQ Electrical Specification

Card Setup
Sealevel Systems ACB-II Page 2
Card Setup
The ACB-II contains several jumper straps for each port which must be set
for proper operation.
Address Selection
The ACB-II occupies 8 consecutive I/O locations. The DIP-switch is used
to set the base address for these locations. Be careful when selecting the
base address as some selections conflict with existing PC ports. The
ACB-II has a total of 8 I/O address selections, if more than one switch is
closed the board will be non-functional. Leaving all eight switches open
will disable the port
12345678
ON
OFF
378-37F HEX
(COM2:)
2F8-2FF HEX
278-27F HEX
(COM1:)
3F8-3FF HEX 3B8-3BF HEX
338-33F HEX
2B8-2BF HEX
238-23F HEX
12345678
ON
OFF
12345678
ON
OFF
12345678
ON
OFF
12345678
ON
OFF
12345678
ON
OFF
12345678
ON
OFF
12345678
ON
OFF
Figure 1 - DIP-Switch Illustration
Refer to Appendix A for common address contentions.
The relative I/O addresses of the ACB-II are as follows:
•Base+0 Channel A Data Port
•Base+1 Channel A Control Port
•Base+2 Channel B Data Port
•Base+3 Channel B Control Port

Card Setup
Sealevel Systems ACB-II Page 3
Interface Selection
Note: Only one interface can be selected at a time.
RS-232
The RS-232 option is selected when the RS-232 driver and receiver are
installed at locations U17 (1488) and U11 (1489).
RS-422
The RS-422 option is installed when the RS-422/485 chips are installed at
U6 (75173) and U7 (75174) and the RS-232 chips are removed.
RS-485
The RS-485 option is installed when the RS-422/485 chips are installed at
U6 (75173) and U7 (75174). The output of the RS-422/485 driver is
capable of being Active (enabled) or Tri-State (disabled) for RS-485
compatibility. Header E2 selects whether the RS-485 driver is enabled by
the SCC signal Request To Send (RTS) or always enabled. With the
jumper installed, RTS enables the driver (RS-485). Removing the jumper
enables the driver regardless of RTS (RS-422). Refer to Appendix C for a
detailed description of RS-422 and RS-485.
IRQ Selection
The ACB-II has an interrupt selection jumper that should be set prior to
use. Consult the user manual for the application software being used to
determine the proper setting. E1 & E9 select the interrupt request for the
port. IRQ3, IRQ4, IRQ5, or no interrupt (removing all jumpers) can be
selected, depending on jumper position. If no interrupt is desired, remove
the jumper.
SCC
4
35
E1 E9
SCC
Figure 2 - Header E1 & E9, IRQ Selection (Shown in Factory Default)

Card Setup
Sealevel Systems ACB-II Page 4
DMA Channel Selection (Header E3)
The Direct Memory Access (DMA) Channel can be selected as Channel 1
or Channel 3. See the Appendix F for jumper position. If DMA is not used,
these jumpers should be removed.
DMA Channel 3
Selected
E3
DMA Channel 1
Selected
E3
Figure 3 - Header E3 DMA Selection
DMA Enable (Header E7)
Header E7 selects whether the DMA Tri-State drivers are enabled, disabled
or whether the RTS from Channel B is used to enable the DMA. The ‘A’
position selects the Always Enabled mode. The ‘B’ position selects RTSB
Enable. Please refer to the Zilog SCC User’s Manual for aid in
programming Write Register 5 for RTSB. Removing the jumper disables
the DMA drivers, and no DMA can be performed.
A
B
Figure 4 - Header E7 DMA Enable (Factory Default)

Card Setup
Sealevel Systems ACB-II Page 5
Miscellaneous I/O Pin Selection (Header E4)
Jumper block E4 allows the user to configure the ACB-II clock and
miscellaneous I/O pins. Please refer to the following illustration for aid in
configuring this header.
RC
RD
TC
DT
TD
Figure 5 - Header E4 (Shown in Factory Default)
Input Pins
Choose only one of the following:
(pin 6 RS-232, pins 8 & 9 RS-422)
RC Selects RXC pin as an input to the DB-25 connector
RD Selects RDB pin as an input to the SCC
Output Pins
Choose only one of the following:
(pin 20 RS-232, pins 20 & 21 RS-422)
TC Selects the TXC pin as an output to the DB-25 connector
DT Selects the DTR pin as an output to the DB-25 connector
TD Selects the TDB pin as an output to the DB-25 connector
Note: While the ACB-II is designed as a single port implementation of the
SCC, the ‘B’ channel Received Data (RDB) and Transmit Data
(TDB) are brought out to the DB-25 through Header E4; allowing
the use of the second port on the SCC in a user definable two port
application.

Installation
Sealevel Systems ACB-II Page 6
Installation
System Installation
The ACB-II can be installed in any of the PC expansion slots. The ACB-II
contains several jumper straps for each port which 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 slot and remove the blank metal slot cover.
4. Gently insert the ACB-II into the slot. Make sure the adapter is seated
properly.
5. Replace the screw.
6. Replace the cover.
7. Connect the power cord.
Installation is complete.

Technical Description
Sealevel Systems ACB-II Page 7
Technical Description
The ACB-II utilizes the Zilog 85230 Serial Communications Controller
(SCC). This chip features programmable baud rate, data format, interrupt
control, and DMA control. Refer to the SCC User’s Manual, the Zilog
Datacom I/C Handbook and the ACB Developers Toolkit diskette for
details on programming the SCC chip.
Features
• Sync/Async Communications using 85230 chip
• DMA supports data rates greater that one million bits per second
• Selectable port address
• Selectable IRQ Level (3,4,5)
• Selectable DMA Channel (1or 3)
• RS-232 or RS-422/485 interface
• Supports TD, RD, RTS, CTS, TXC, RXC Signals
• Jumper options for clock source
• Software programmable baud rate
• Software Toolkit provided
• Short card, DB-25 male connector
Programable Baud Rate Generator
The baud rate of the SCC is programmed under software control. The
standard oscillator supplied with the board is 7.3728 Megahertz (MHz).
Other values may be substituted to achieve a higher or different baud rate,
if required, by replacing the oscillator (U9) with a different part. Refer to
the SCC User’s Manual and the ACB Developers Toolkit diskette for baud
rate divisors and programming information.

Technical Description
Sealevel Systems ACB-II Page 8
Connector Pin Assignments
RS-422
Signal Name Pin # Mode
GND Ground 7
RX+ Receive Positive 12 Input
RX- Receive Negative 13 Input
CTS+ Clear To Send Positive 10 Input
CTS- Clear To Send Negative 11 Input
RXC+ Receive Clock Positive 8 Input
RXC- Receive Clock Negative 9 Input
TX+ Transmit Positive 24 Output
TX- Transmit Negative 25 Output
RTS+ Request To Send Positive 22 Output
RTS- Request To Send Negative 23 Output
TXC+ Transmit Clock Positive 20 Output*
TXC- Transmit Clock Negative 21 Output*
DTR+ Data Terminal Ready Positive 20 Output*
DTR- Data Terminal Ready Negative 21 Output*
RS-232
Signal Name Pin # Mode
GND Ground 7
RD Receive Data 3 Input
CTS Clear To Send 5 Input
RXC Receive Clock** 6 Input
TD Transmit Data 2 Output
RTS Request To Send 4 Output
TXC Transmit Clock** 20 Output*
DTR Data Term Ready 20 Output*
* Note: These pins are determined by the Header E4 position setting.
** Note: These pins are not normally clock lines. Pins 15 and 17 are the
normal RS-232 clock lines. If your equipment utilizes these clock
signals, connect the TXC to pin 20, and the RXC to pin 6.

Specifications
Sealevel Systems ACB-II Page 9
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
• IPC 610-A Class-III standards are adhered to with a 0.1 visual A.Q.L.
and 100% Functional Testing.
• All Sealevel Systems Printed Circuit Boards are built to U.L. 94V0
rating and are 100% electrically tested. Printed Circuit Boards are
solder mask over bare copper or solder mask over tin nickel.
Power Consumption
Supply line +12 VDC -12 VDC +5 VDC
Rating 50 mA 50 mA 275 mA
Mean Time Between Failures (MTBF)
Greater than 150,000 hours. (Calculated)
Physical Dimensions
Board Length 4.6 inches (11.68 cm)
Board Height including Goldfingers 4.2 inches (10.66 cm)
Board Height excluding Goldfingers 3.9 inches (9.906 cm)

Appendix A - Troubleshooting
Sealevel Systems ACB-II Page 10
Appendix A - Troubleshooting
An Advanced Communications Board Developers Toolkit Diskette 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 using a unique IRQ. While
the Sealevel Systems adapter does allow the sharing of IRQ’s, many
other adapters (i.e. SCSI adapters and on-board serial ports) do not.
The IRQ is typically selected via an on-board header block. Refer to
the section on Card Setup for help in choosing an I/O address and IRQ.
4. Make sure the Sealevel Systems adapter is securely installed in a
motherboard slot.
5. Use the supplied diskette and User Manual to verify that the Sealevel
Systems adapter is configured correctly. The supplied diskette contains
a diagnostic program ‘SSDACB’ that will verify if an adapter is
configured properly. This diagnostic program is written with the user
in mind and is easy to use. Refer to the ‘README.txt’ file on the
supplied diskette for detailed instructions on using ‘SSDACB’.

Appendix A - Troubleshooting
Sealevel Systems ACB-II Page 11
6. The following are known I/O conflicts:
• The 278 and 378 settings may conflict with your printer I/O
adapter.
• 3B8-3BF cannot be used if a Monochrome adapter is
installed.
• 3F8-3FF is typically reserved for COM1:
• 2F8-2FF is typically reserved for COM2:
• 238-23F may conflict with a Bus Mouse
7. Please refer to your included diskette for any post production manual
updates and application specific information.
8. Always use the Sealevel Systems diagnostic software when
Troubleshooting a problem. This will eliminate the software issue from
the equation.

Appendix B - How To Get Assistance
Sealevel Systems ACB-II Page 12
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.htm .
4. 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.
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.

Appendix C - Electrical Interface
Sealevel Systems ACB-II Page 13
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. It is defined by the EIA as the
Interface between Data Terminal Equipment and Data Circuit-
Terminating Equipment Employing Serial Binary Data Interchange. The
mechanical implementation of RS-232 is on a 25 pin D sub connector.
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 often operates at 38.4 Kbps over very short
distances. The voltage levels defined by RS-232 range from -12 to +12
volts. 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. A voltage of +12 volts (usually +3 to +10
volts) represents a binary 0 (space) and -12 volts (-3 to -10 volts) denotes a
binary 1 (mark). The RS-232 and the EIA/TIA-574 specification defines
two type of interface circuits, Data Terminal Equipment (DTE) and Data
Circuit-Terminating Equipment (DCE). The Sealevel Systems adapter is a
DTE 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.

Appendix C - Electrical Interface
Sealevel Systems ACB-II Page 14
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. 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) controls the state of the driver. Some communication
software packages refer to RS-485 as RTS enable or RTS block mode
transfer. 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.

Appendix D - Direct Memory Access
Sealevel Systems ACB-II Page 15
Appendix D - Direct Memory Access
In many instances it is necessary to transmit and receive data at greater
rates than would be possible with simple port I/O. In order to provide a
means for higher rate data transfers, a special function called Direct
Memory Access (DMA) was built into the original IBM PC. The DMA
function allows the ACB-II (or any other DMA compatible interface) to
read or write data to or from memory without using the Microprocessor.
This function was originally controlled by the Intel 8237 DMA controller
chip, but may now be a combined function of the peripheral support chip
sets (i.e. Chips & Technology or Symphony chip sets).
During a DMA cycle the DMA controller chip is driving the system bus in
place of the Microprocessor, providing address and control information.
When an interface needs to use DMA it activates a DMA request signal
(DRQ) to the DMA controller, which in turn sends a DMA hold request to
the Microprocessor. When the Microprocessor receives the hold request it
will respond with an acknowledge to the DMA controller chip. The DMA
controller chip then becomes a Bus Master providing the necessary control
signals to complete a Memory to I/O or I/O to Memory transfer. When the
data transfer is started an acknowledge signal (DACK) is sent by the DMA
controller chip to the ACB-II. Once the data has been transferred to or
from the ACB-II, the DMA controller returns control to the
Microprocessor.
To use DMA with the ACB-II requires a thorough understanding of the PC
DMA functions . The ACB Developers Toolkit demonstrates the setup and
use of DMA with several source code and high level language demo
programs. Please refer to the SCC User’s Manual, the PC Technical
Reference and the 8237 DMA controller chip specification for more
information.

Appendix E - Synchronous and Asynchronous Communications
Sealevel Systems ACB-II Page 16
Appendix E - Asynchronous and Synchronous
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 or sync characters) are pre-defined and must correspond at
both the transmitting and receiving ends. The techniques used for serial
communications can be divided into two groups, synchronous and
asynchronous.
When contrasting synchronous and asynchronous serial communications,
the fundamental differences deal with how each method defines the
beginning and the end of a character or group of characters. The method of
determining the duration of each bit in the data stream is also an important
difference between synchronous and asynchronous communications. The
remainder of this section is devoted to detailing the differences between
character framing and bit duration implemented in synchronous and
asynchronous communications.
Asynchronous Communications
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. Character boundaries
for asynchronous communications are defined by a starting bit followed by
a pre-defined number of data bits (5, 6, 7, or 8). The end of the character is
defined by the transmission of a pre-defined number of stop bits (usual 1,
1.5 or 2). An extra bit used for error detection is often appended before the
stop bits.

Appendix E - Synchronous and Asynchronous Communications
Sealevel Systems ACB-II Page 17
1
1.5
2
Stop Bits
Parity
Bit
5 to 8 Data Bits
Odd
Even
or
Unused
Remain Idle
or
Next Start Bit
1
0
Idle State
of
Line
Figure 6 - 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 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).