User`s manual

26 PCI-1753 User's Manual
3.3.7 Pattern Match Interrupt Function
The PCI-1753/1753E provides the pattern match interrupt function
for port A0. It monitors the status of the enabled input channels,
which are chosen in Base+24 (or Base+56 for the PCI-1753E), and
compares the received state values with the pre-set state values
written in Base+20 (Base+52 for the PCI-1753E). When the actual
state values match the pre-set state values, the PCI-1753 will deliver
an interrupt signal to the system. This function releases the CPU from
the burden of polling all of the I/O points, enabling a PC to handle
more I/O points with higher performance. The following is an
example.
Example 3.1 Assume that the pattern match function for the I/O
channels PA01, PA02, PA06 and PA07 of the PCI-1753 is enabled (i.e.
PA00, PA03, PA04 and PA05 on the PCI-1753 and port A0 on the PCI-
1753E are ignored during the pattern match monitoring process). The
user can set the pattern match values for the enabled input channels,
and these will be compared to the actual channel states of the enabled
channels. The following is an example.
a) First, enable the pattern match interrupt function for channels
PA01, PA02, PA06 and PA07
b) Write the pre-set pattern-match state of the enabled channels
Bit # 76543210
Base+24 11000110
Bit # 76543210
Base+20 10XXX 1 1X