User`s manual

26 Operation Theory
72XX Series
User’s Manual
4.1.4 Digital I/O Port Programming
Users can write the digital output value to or read back the digital
signal level from the PPI ports by using the software library. The
port names are defined in Table 4.1. These port names are used
throughout this manual as well as in the software library. The pro-
gramming for PCI-7224/7248/7296, PCIe-7248/7296, and cPCI-
7248 are fully compatible.
There are four ports on every 8255 PPI, including ports A, B, C,
and the control port. PA, PB, and PC could be written or read but
the control port is write only. Refer to chapter 5 for more details on
the programming of DIO ports.
Connector CN1 CN2 CN3 CN4
Port
Names
P1A P2A P3A P4A
P1B P2B P3B P4B
P1C P2C P3C P4C
P1CTRL P2CTRL P3CTRL P4CTRL
Table 4-1: I/O Port Names