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© Sealevel Systems, Inc.
8002H Manual | SL9021 9/2021
Programming the DIO-16.PCI, Continued
Direct Hardware Control
In systems where the user’s program has direct access to the hardware (i.e., DOS) the table below gives
the mapping and functions that the
DIO-16.PCI
provides.
R = Read
R/W = Read or Write
Function Available
Port
Address Hex
Port Type
RD
A
Base+0
Input Port (Opto Input)
B
Base+1
Not Assigned
R/W
C
Base+2
Output Port (Reed Relays)
D
Base+3
Not Assigned
RD = Read, RD/WR = Read or Write
Reading the Inputs
The inputs are active Low. If no voltage is applied across one of the differential inputs, it returns a one on
that bit. If an AC or DC voltage is applied, it returns a zero on that bit.
Reading the Outputs
The relay ports return the ones complement of the value that is currently being used to drive the relays.
Writing the Outputs
The output ports are the only ports that can be written. The relays on a standard DIO-32.PCI are normally
open. To close a relay a one must be written to the appropriate bit.
