Advantech PCI-1751U, User Manual

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PCI-1751U User Manual 8
2.3.2 Using Jumpers to Set Ports as Output Ports
By shorting the lower two pins of the jumpers JPA0, JPB0, JPC0L,
JPC0H, JPA1, JPB1, JPC1L or JPC1H, a user sets the corresponding
ports to be output ports. (JPA0 means jumper for port A0, JPB0 means
jumper for port B0, etc.) Shorting the lower two pins of a port's jumper
pins disables the port from being software configurable as an input port.
The initial state of each of these ports after system power on or reset will
be logic 0 (voltage low), unless jumper JA1 determines otherwise. (See
Jumper JA1 below.)
2.3.3 Restore Ports to Condition Prior to Reset
Jumper JA1 gives the PCI-1751U a new and valuable capability. With
JA1 enabled, the PCI-1751U "memorizes" all port I/O settings and output
values, and, in the event of a "hot" reset, the settings and output values
present at the port just prior to reset are restored to each port following
reset. This feature applies to both ports set by software, and to ports con-
figured as output ports via jumper. Depending on the application, this
capability may allow a card to be reset without requiring a complete shut-
down of processes controlled by the card (since port values are left
unchanged and are interrupted only momentarily).
Complete loss of power to the chip clears chip memory. Thus, even if
JA1 is enabled, if the power to the card is disconnected, the card's initial
power-on state will be the default state (for software-set ports) or the state
of an output port with voltage low output (for jumper-set ports).
When jumper JA1 is not enabled, power-off or reset results in ports
returning to their default state (for software-set ports) or returning to the
state of output port with voltage low output (for jumper-set ports).