User`s manual

28 Operation Theory
72XX Series
User’s Manual
4.1.6 Power On Configuration
The default configuration after power on, hardware reset, or soft-
ware reset sets all ports as input ports. Therefore, users do not
need to worry about damaging external devices when system is
on. In addition, the default signal level can be pulled high or pulled
low by setting the jumpers. Refer to section 2.7 for setting the
power on status of the DIO ports.
4.1.7 Note for Output Data
Be careful of the initial condition of digital output signals. If users
set the control word as output port after power on, the previous
uncertain output value will be put on the output pins immediately.
Therefore, BE SURE TO WRITE A SAFE VALUE TO THE
PORTS BEFORE CONFIGURING THEM AS OUTPUT PORTS.
4.1.8 Note for cPCI-7249R
The P1AE, P1BE, P1CE, P2AE, P2BE, and P2CE registers latch
data from P1A, P1B, P1C, P2A, P2B, and P2C respectively. The
latch signal is from Pin 99 of the 100-pin connector.