User Manual Owner's manual
© Sealevel Systems, Inc. 
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SEALINK ISO-16 User Manual
Programming the SEALINK ISO-16 
Sealevel’s SeaI/O software is provided to assist in the development of reliable 
applications for the Sealevel Systems family of digital I/O adapters. Included on the 
SeaI/O CD are driver functions for use in accessing the I/O as well as helpful 
samples and utilities. 
Programming for Windows 
The SeaI/O API (Application Programmer Interface) provides a variety of useful 
high-level function calls implemented in a Windows dynamic link library (DLL). 
The API is defined in the help file (Start/Programs/SeaIO/SeaIO Help) under 
“Application Programmers Interface”. This help file also includes detailed 
information dealing with installation / removal of the software and information 
about latency, logic states, and device configuration. 
For C language programmers we recommend using the API to access the SEALINK 
ISO-16. If you are programming in Visual Basic, using the ActiveX control 
included with SeaI/O is advised. 
Samples and Utilities 
A variety of sample programs and utilities (both executable and source code) are 
included with SeaI/O. Further documentation on these samples can be found by 
selecting “Start/Programs/SeaIO/Sample Application Description”. Information 
about where the files are physically stored on your disk is also included in this same 
file. 
Digital I/O Interface 
The SeaLINK ISO-16 provides two parallel input/output (I/O) ports. The ports are 
organized as ports A and B. The SeaLINK ISO-16 is a line-powered device 
requiring a USB port capable of sourcing 500 mA. 
Serial String 
Each device has an eight digit alphanumeric serial string stored in non-volatile 
memory. On the Windows platforms, this number is used to give each unit a 
separate identity. This identity allows the device to be moved to any USB port or 
hub port on your computer while retaining its device number. If a device becomes 
damaged and is replaced the new device should be given the same serial string as the 
device it is replacing. This string is stored in an EEPROM along with other critical 
information. This EEPROM is read during enumeration. The device should not be 
unplugged during its enumeration due to remote possibility that the data in the 
EEPROM could be corrupted if power is removed during a read/write cycle to the 
EEPROM. Enumeration is complete when the LED is lit. 
The control panel utility provides the capability to read or modify this string. 
However, setting the same string for two units connected to the same computer will 
cause the second unit to fail enumeration, and make it invisible to the operating 
system. Should this occur, unplug one unit and set the serial string for the other unit 
to a different string. 










