Programming The Dio-32.Pci - SeaLevel DIO-32.PCIe User Manual

Programming the DIO-32.PCI

Sealevel's SeaI/O Classic software is provided to assist in the development of reliable applications for the
Sealevel Systems family of PCI and PCI Express digital I/O adapters. Included in Sealevel's software 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 DIO-32.PCI. 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 system is also
included in this same file.
Programming for Linux
SeaI/O for Linux consists of two major parts: a kernel module and a library. The kernel module is a simple
IO pass-through device, allowing the library to handle the more sophisticated functions provided to SeaI/O
users. It is provided in a 'tarball' format and can easily be compiled and included in the kernel build.
Input Ports
Ports A and B are 8 bit input ports connected to optically isolated input sensors. Each sensor can be used
to interface a voltage input and then sense whether the voltage is on or off. Each sensor is isolated (with
respect to a common ground) from every other sensor, and also isolated with respect to the host PC ground.
This means that signals such as low-level AC line voltage, e.g. 12 or 24VAC, motor servo voltage, and
control relay signals can be 'sensed', or read by the PC, without the risk of damage due to ground loops or
ground faults.
Each sensor input pair has a current limiting resistor that is used to limit the input current to the opto-
isolator. The opto-isolator has two 'back-to-back' diodes internally. This allows AC or DC signals to be
sensed, regardless of polarity. When the applied voltage is high enough to cause the LED in the opto-isolator
to turn-on, the output of the opto-isolator goes low (0 volts), and the signal is read as a low logic level (binary
0) by the PC. When the input signal is too low to turn on the opto-isolator, the output goes high, and the port
bit is read by the PC as a high logic level (binary 1). While this is true at the hardware level, the Microsoft
Windows driver gives the application the ability to use Positive or Negative Logic. This card defaults to
Positive Logic and therefore the driver inverts the logic level BEFORE the information is returned to the
11
© Sealevel Systems, Inc. 8004e Manual | SL9207 12/2022