SeaLevel ISO-COMM User manual

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
ISO-COMM
User Manual | 3415, 3416, 3417, 3418, 3419

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Contents
CONTENTS............................................................................................................................................................................................................................2
INTRODUCTION...................................................................................................................................................................................................................3
BEFORE YOU GET STARTED..............................................................................................................................................................................................4
CARD SETUP........................................................................................................................................................................................................................6
INSTALLATION...................................................................................................................................................................................................................12
TECHNICAL DESCRIPTION..............................................................................................................................................................................................13
SPECIFICATIONS...............................................................................................................................................................................................................15
APPENDIX A –TROUBLESHOOTING.............................................................................................................................................................................16
APPENDIX B –HOW TO GET ASSISTANCE...................................................................................................................................................................17
APPENDIX C –ELECTRICAL INTERFACE......................................................................................................................................................................18
APPENDIX D –ASYNCHRONOUS COMMUNICATIONS.............................................................................................................................................19
APPENDIX E –SILK SCREEN ..........................................................................................................................................................................................20
APPENDIX D –COMPLIANCE NOTICES........................................................................................................................................................................22
WARRANTY ........................................................................................................................................................................................................................23

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Introduction
Overview
The Sealevel Systems ISO-COMM provides the PC with additional ground isolated serial ports for terminals,
modems, printers, etc. 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 phenomena that leads to the failure (and destruction) of communication
interfaces. The ISO-COMM isolated boards provide up to 500 volts DC of isolation.
The ISO-COMM provides two or four DOS and Windows compatible serial ports, and also offers extended
‘AT’ interrupts. Each port is independently addressable as COM1: through COM4:, or any other I/O address
up to 3FF Hex.

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Before You Get Started
What’s Included
The ISO-COMM is shipped with the following items. If any of these items are missing or damaged,
contact the supplier.
•ISO-COMM Serial I/O Adapter
•Cable providing 2 DB-9 connectors.
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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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Before We Get Started, Continued
Factory Default Settings
The ISO-COMM factory default settings are as follows:
Port #
Base Address
IRQ
Port 1
3F8
4
Port 2
2F8
3
Port 3
3E8
4
Port 4
2E8
3
For your reference, record installed ISO-COMM settings below:
Port #
Base Address
IRQ
Port 1
Port 2
Port 3
Port 4

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Card Setup
The ISO-COMM contains several jumper straps which must be set for proper operation.
Address Selection
Each port on the ISO-COMM occupies 8 consecutive I/O locations. A 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 ports. The following table shows several examples that typically do not cause a conflict. SW4 sets
the I/O address for port 1, SW3 sets the address for port 2, SW2 sets the address for port 3 and SW1 sets
the address for port 4.
Address
Binary
Switch Position Setting
Hex
A9 A0
1
2
3
4
5
6
7
280-287
1010000XXX
Off
On
Off
On
On
On
On
2A0-2A7
1010100XXX
Off
On
Off
On
Off
On
On
2E8-2EF
1011101XXX
Off
On
Off
Off
Off
On
Off
2F8-2FF
1011111XXX
Off
On
Off
Off
Off
Off
Off
3E8-3EF
1111101XXX
Off
Off
Off
Off
Off
On
Off
300-307
1100000XXX
Off
Off
On
On
On
On
On
328-32F
1100101XXX
Off
Off
On
On
Off
On
Off
3F8-3FF
1111111XXX
Off
Off
Off
Off
Off
Off
Off
Figure 1 - Address Selection Table
The following illustration shows the correlation between the DIP-switch setting and the address bits used
to determine the base address. In the example below, address 300 is selected as a base. Address 300 in
binary is XX11 0000 0XXX where X = a non-selectable address bit.
A9 A3E
Figure 2 - DIP Switch Illustration
Setting the switch ‘On’ or ‘Closed’ corresponds to a ‘0’ in the address, while leaving it ‘Off’ or ‘Open’
corresponds to a ‘1’.
Refer to Appendix A for common address contentions.
1
2
3
4
5
6
7
ON
OFF
8

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Card Setup, Continued
Port Enable / Disable
Each port on the ISO-COMM can be enabled or disabled with switch position 8 on the DIP-switch. The port
is enabled with the switch ‘On’ or ‘Closed’ and disabled when ‘Off’ or ‘Open’. If any port is disabled, be sure
to disable the interrupt request for that port by removing the IRQ jumper.
IRQ Selection
Headers E1, E2, E3 and E4 select the IRQ for each serial port. If COM1: is selected, this jumper must be on
the IRQ4 setting. If COM2: is selected, this jumper must be on IRQ3.
E4 - Port1
E3 - Port2
E2 - Port3
E1 - Port4
Most communications software applications default COM3: to IRQ4 and COM4: to IRQ3. This requires
the sharing of interrupts between COM1: and COM3:, and between COM2: and COM4:. While this is the
default, it is not always the preferred setting. Check your software configuration instructions to
determine the most appropriate IRQ selection.
Interrupt Mode Options
Header E5 selects the interrupt mode for each port. Each port must be set in the correct mode to insure
proper installation.
‘N’ indicates the (N)ormal, single interrupt per port mode. ‘S’ Indicates the (S)hared interrupt mode, which
allows more than one port to access a single IRQ. Any two or more ports can share a common IRQ by
placing the jumpers on the same IRQ setting and setting the appropriate selections at E5. Consult your
particular software for IRQ selection. If no interrupt is desired, remove the jumper. ‘M’ indicates the
inclusion of a 1K ohm pull-down resistor required on one port when sharing interrupts.
Figure 3 - Headers E1, E2, E3, and E4 (Factory Default)

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Card Setup, Continued
E5
1 2
M
S
N
M
S
N
3 4
Figure 4 - Header E5, Normal IRQ Mode
Set jumpers to ‘S’ for shared interrupt mode on all blocks sharing an IRQ except one. Set that port block
for ‘M’. This provides the pull-down resistor circuit that makes sharing of IRQs possible. If you are using
more than one ISO-COMM or a compatible card in a bus you should only have one port set to ‘M’. The
following example shows all four ports sharing a single IRQ.
E5
1 2
M
S
N
M
S
N
3 4
Figure 5 - Header E5, Shared IRQ Mode
Set jumper to ‘S’ if you are using more than one ISO-COMM in a bus or wish to completely remove the pull-
down resistor for hardware compatibility.

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Card Setup, Continued
Setting the board in this configuration when it is not accompanied by a pulldown resistor will prevent the
ports from triggering an interrupt.
E5
1 2
M
S
N
M
S
N
3 4
Figure 6 - Header E5, Sharing IRQs with another adapter
E4 - Port1
E5
1 2 M
SE3 - Port2
N
M
S
N
3 4E2 - Port3
E1 - Port4
Figure 7 - IRQ Headers E1 - E5 (Factory Default)

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© Sealevel Systems, Inc. 3415, 3416, 3417, 3418, 3419 Manual | SL9149 11/2021
Card Setup, Continued
The above example shows the correlation between jumper block E5 and the interrupt jumpers (E1-E4). This
example shows the ISO-COMM shipping configuration with COM1: & COM3: sharing interrupt 4 and COM2:
& COM4: sharing interrupt 3.
Headers E8 and E9
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 PCs to be connected in a multi-drop bus and selectively polled. Half duplex
two-wire operation is also possible by connecting TX+ to RX+ and TX- to RX- in your cable hood. The enable
to the driver is connected to the UART Request To Send (RTS) line for RS-485 communications. This allows
the RS485 driver to be tri-stated when inactive on a multi-drop polled network. The software that you are
using must "know how" to enable the driver when it is answering a poll. Failure to correctly set this jumper
can cause transmitter contention problems preventing operation by any nodes on the network. Sealevel
Systems communication software is compatible with this mode of operation. To enable the driver with RTS
install jumpers at E9-A for port 1, E9-C for port 2, E8-A for port 3 and E8-C for port 4.
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 the ‘echoing’
(i.e., using received characters to throttle the transmitter) or it can confuse the system if the software does
not. The RS-485 echo can also be disabled at E8 and E9. To disable the echo, install a jumper at E9-B for
port 1, E9-D for port 2, E8-B for port 3 and E8-D for port 4.
The following example shows the driver in the RS-485 mode and the echo enabled.
E8 & E9D
C B
A
Figure 8 - Headers E8 and E9 RS-485 Mode Enable