User manual

PCI-1753/1753E User Manual 26
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 chan-
nels. 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
c) Finally, enable the pattern match function for port A0 of the PCI-1753
by writing a “1” in bit 0 of Base+16.
Bit #
76543210
Base+24
11000110
Bit #
76543210
Base+20
10XXX11X
M2 Description
1 Enable the change of state interrupt function for port A0
0 Disable the change of state interrupt function for port A0