Omega Engineering OMG-PCI-DIO48 - Manual (Page 18)

Technical Description
OMG-PCI-DIO48 Page 14
C1-6 C2-6
C1-7 C2-7
Figure 9-(Print and fill in for your configuration)
Direct Hardware Control
In systems where the users program has direct access to the hardware (DOS) the tables below
gives the mapping and functions that the 8005 provide. The address of each eight-bit port is
calculated as shown in the table on the following page, the cards base address p lus an offset.
Reading the Inputs:
The inputs are active high. If an input is driven high (2V to 5.25 V) it will read as a logical one (1), if
driven low (0V to 0.8V) it will read as a logical zero (0). If an input is not driven it will read as a one
due to the 10K ohm pull up resistors on each port.
Reading the Outputs:
The value that is currently being used to drive the outputs will be returned.
Presetting an Output Port:
Each port has an output register associated with it. This register may be written and retains its
value whether the port is configured as an input or an output. To preset the value of an output port
the program should write to the port when it is configured as an input then configure it as an
output.
Writing the Outputs:
The outputs are active high. Writing a one (1) corresponds to 5V while writing a zero (0)
corresponds to 0V, at the output.
Bit Set/Reset
Port C supports bit set/reset as shown in the tables below.
Port Configuration:
Each port can be configured as an input or an output by writing to its direction control bit, refer to
the tables below.