Keithley KPCI-PIO32IOA, User Manual

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3-12 Installation KPCI-PIO32IOA and KPCI-PDISO8A User’s Manual
Wiring I/O to your external circuits
WARNING Ensure that both the computer and the external circuits are turned
OFF before making any connections to avoid a possible shock
hazard.
Input and output precautions
Over-current conditions
CAUTION The KPCI output channels are not designed to handle over-current
conditions. A protected source that is compatible with the KPCI
specifications should always be used. If this is not possible, external
over-current protection is required to protect both the KPCI and the
rest of the system.
Transient voltages
CAUTION The KPCI card provides limited input and output protection to pro-
tect the user PC against high voltage events such as ESD strikes and
voltage surges. If, however, voltage transients over 100V peak are
expected to occur frequently, as with highly inductive load switch-
ing, then external protection should be provided to reduce repetitive
stresses on the KPCI card, source and load.
Non-isolated power pins
CAUTION The KPCI card provides fuse-pro5V and ground for conve-
nient use in external circuits. This voltage is supplied from the bus
and is not isolated from the user PC. If isolation is a requirement in
the application, then this supply should either not be used at all, or
be used with some external means of isolating this supply.
Power-up state of channels
NOTE
The power-up state of the input and output channels is as follows:
•
Input channels — For |V| <
≅
45V, Z
≅
22k
Ω.
For |V| > 45V,
Z
≅
17k
Ω
. These channels are always configured as inputs and can
be driven at all times.
•
Output channels — These are form A, N.O. SPST style contacts. The
output channels are in a high-impedance state (see specifications in
Appendix A ) under any of the following conditions:
–
The KPCI card is in the system reset state.
–
The system and KPCI card are unpowered.
–
The system and the KPCI card are powered but no software com-
mand has been given for actuation (initial state). This state is also
configurable in DriverLINX.